From ce850bf8733cf65f9c9c3fb9208edc113fa97e3d Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Wed, 29 Oct 2025 12:50:47 +0000
Subject: [PATCH 1/8] array_chunks: slightly improve docs

---
 library/core/src/array/mod.rs                  | 7 ++++---
 library/core/src/iter/adapters/array_chunks.rs | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 0dc10758a8560..312c8da107475 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -907,7 +907,7 @@ where
 /// All write accesses to this structure are unsafe and must maintain a correct
 /// count of `initialized` elements.
 ///
-/// To minimize indirection fields are still pub but callers should at least use
+/// To minimize indirection, fields are still pub but callers should at least use
 /// `push_unchecked` to signal that something unsafe is going on.
 struct Guard<'a, T> {
     /// The array to be initialized.
@@ -925,7 +925,7 @@ impl<T> Guard<'_, T> {
     #[inline]
     pub(crate) unsafe fn push_unchecked(&mut self, item: T) {
         // SAFETY: If `initialized` was correct before and the caller does not
-        // invoke this method more than N times then writes will be in-bounds
+        // invoke this method more than N times, then writes will be in-bounds
         // and slots will not be initialized more than once.
         unsafe {
             self.array_mut.get_unchecked_mut(self.initialized).write(item);
@@ -954,7 +954,7 @@ impl<T> Drop for Guard<'_, T> {
 /// `next` at most `N` times, the iterator can still be used afterwards to
 /// retrieve the remaining items.
 ///
-/// If `iter.next()` panicks, all items already yielded by the iterator are
+/// If `iter.next()` panics, all items already yielded by the iterator are
 /// dropped.
 ///
 /// Used for [`Iterator::next_chunk`].
@@ -986,6 +986,7 @@ fn iter_next_chunk_erased<T>(
     buffer: &mut [MaybeUninit<T>],
     iter: &mut impl Iterator<Item = T>,
 ) -> Result<(), usize> {
+    // if `Iterator::next` panics, this guard will drop already initialized items
     let mut guard = Guard { array_mut: buffer, initialized: 0 };
     while guard.initialized < guard.array_mut.len() {
         let Some(item) = iter.next() else {
diff --git a/library/core/src/iter/adapters/array_chunks.rs b/library/core/src/iter/adapters/array_chunks.rs
index 8f1744fc5fbb7..ff83b2010490f 100644
--- a/library/core/src/iter/adapters/array_chunks.rs
+++ b/library/core/src/iter/adapters/array_chunks.rs
@@ -89,7 +89,7 @@ where
             match self.iter.next_chunk() {
                 Ok(chunk) => acc = f(acc, chunk)?,
                 Err(remainder) => {
-                    // Make sure to not override `self.remainder` with an empty array
+                    // Make sure to not overwrite `self.remainder` with an empty array
                     // when `next` is called after `ArrayChunks` exhaustion.
                     self.remainder.get_or_insert(remainder);
 

From 786cca82d24e6a29e66e1d945492db911cae0020 Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Wed, 10 Sep 2025 13:33:45 +0000
Subject: [PATCH 2/8] slice iter: replace manual saturating_sub

---
 library/core/src/slice/iter.rs | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 7053ae86e732f..10dd6ada30260 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -2368,10 +2368,7 @@ impl<'a, T> Iterator for RChunks<'a, T> {
         } else {
             // Can't underflow because of the check above
             let end = self.v.len() - end;
-            let start = match end.checked_sub(self.chunk_size) {
-                Some(sum) => sum,
-                None => 0,
-            };
+            let start = end.saturating_sub(self.chunk_size);
             let nth = &self.v[start..end];
             self.v = &self.v[0..start];
             Some(nth)
@@ -2391,10 +2388,7 @@ impl<'a, T> Iterator for RChunks<'a, T> {
 
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
-        let start = match end.checked_sub(self.chunk_size) {
-            None => 0,
-            Some(start) => start,
-        };
+        let start = end.saturating_sub(self.chunk_size);
         // SAFETY: mostly identical to `Chunks::__iterator_get_unchecked`.
         unsafe { from_raw_parts(self.v.as_ptr().add(start), end - start) }
     }
@@ -2571,10 +2565,7 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
 
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
-        let start = match end.checked_sub(self.chunk_size) {
-            None => 0,
-            Some(start) => start,
-        };
+        let start = end.saturating_sub(self.chunk_size);
         // SAFETY: see comments for `RChunks::__iterator_get_unchecked` and
         // `ChunksMut::__iterator_get_unchecked`, `self.v`.
         unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), end - start) }

From c62abb65c773654c9e8f65f5f115a3fce441781c Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Thu, 11 Sep 2025 11:05:03 +0000
Subject: [PATCH 3/8] slice iter: cleanup and make similar Chunks[Mut]::nth

---
 library/core/src/slice/iter.rs | 44 +++++++++++++++-------------------
 1 file changed, 19 insertions(+), 25 deletions(-)

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 10dd6ada30260..8ca78941a8a55 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -1537,13 +1537,13 @@ impl<'a, T> Iterator for Chunks<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let (start, overflow) = n.overflowing_mul(self.chunk_size);
-        // min(len) makes a wrong start harmless, but enables optimizing this to brachless code
-        let chunk_start = &self.v[start.min(self.v.len())..];
-        let (nth, remainder) = chunk_start.split_at(self.chunk_size.min(chunk_start.len()));
-        if !overflow && start < self.v.len() {
-            self.v = remainder;
-            Some(nth)
+        if let Some(start) = n.checked_mul(self.chunk_size)
+            && start < self.v.len()
+        {
+            let rest = &self.v[start..];
+            let (chunk, rest) = rest.split_at(self.chunk_size.min(rest.len()));
+            self.v = rest;
+            Some(chunk)
         } else {
             self.v = &self.v[..0]; // cheaper than &[]
             None
@@ -1613,10 +1613,7 @@ impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
             None
         } else {
             let start = (len - 1 - n) * self.chunk_size;
-            let end = match start.checked_add(self.chunk_size) {
-                Some(res) => cmp::min(self.v.len(), res),
-                None => self.v.len(),
-            };
+            let end = (start + self.chunk_size).min(self.v.len());
             let nth_back = &self.v[start..end];
             self.v = &self.v[..start];
             Some(nth_back)
@@ -1719,22 +1716,19 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
-        let (start, overflow) = n.overflowing_mul(self.chunk_size);
-        if start >= self.v.len() || overflow {
+        if let Some(start) = n.checked_mul(self.chunk_size)
+            && start < self.v.len()
+        {
+            // SAFETY: `start < self.v.len()` ensures this is in bounds
+            let (_, rest) = unsafe { self.v.split_at_mut(start) };
+            // SAFETY: `.min(rest.len()` ensures this is in bounds
+            let (chunk, rest) = unsafe { rest.split_at_mut(self.chunk_size.min(rest.len())) };
+            self.v = rest;
+            // SAFETY: Nothing else points to or will point to the contents of this slice.
+            Some(unsafe { &mut *chunk })
+        } else {
             self.v = &mut [];
             None
-        } else {
-            let end = match start.checked_add(self.chunk_size) {
-                Some(sum) => cmp::min(self.v.len(), sum),
-                None => self.v.len(),
-            };
-            // SAFETY: The self.v contract ensures that any split_at_mut is valid.
-            let (head, tail) = unsafe { self.v.split_at_mut(end) };
-            // SAFETY: The self.v contract ensures that any split_at_mut is valid.
-            let (_, nth) = unsafe { head.split_at_mut(start) };
-            self.v = tail;
-            // SAFETY: Nothing else points to or will point to the contents of this slice.
-            Some(unsafe { &mut *nth })
         }
     }
 

From a7ee7c8cbef695faf8449d09c542d12127a6aba9 Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Thu, 11 Sep 2025 15:09:21 +0000
Subject: [PATCH 4/8] slice iter: more cleanup

---
 library/core/src/slice/iter.rs   | 110 +++++++++++++------------------
 library/coretests/tests/slice.rs |   7 ++
 2 files changed, 52 insertions(+), 65 deletions(-)

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 8ca78941a8a55..925910400eade 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -1415,26 +1415,21 @@ impl<'a, T> Iterator for Windows<'a, T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
     #[inline]
-    fn next_back(&mut self) -> Option<&'a [T]> {
-        if self.size.get() > self.v.len() {
-            None
-        } else {
-            let ret = Some(&self.v[self.v.len() - self.size.get()..]);
-            self.v = &self.v[..self.v.len() - 1];
-            ret
-        }
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.nth_back(0)
     }
 
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
-        let (end, overflow) = self.v.len().overflowing_sub(n);
-        if end < self.size.get() || overflow {
+        if let Some(end) = self.v.len().checked_sub(n)
+            && let Some(start) = end.checked_sub(self.size.get())
+        {
+            let res = &self.v[start..end];
+            self.v = &self.v[..end - 1];
+            Some(res)
+        } else {
             self.v = &self.v[..0]; // cheaper than &[]
             None
-        } else {
-            let ret = &self.v[end - self.size.get()..end];
-            self.v = &self.v[..end - 1];
-            Some(ret)
         }
     }
 }
@@ -1523,9 +1518,7 @@ impl<'a, T> Iterator for Chunks<'a, T> {
         if self.v.is_empty() {
             (0, Some(0))
         } else {
-            let n = self.v.len() / self.chunk_size;
-            let rem = self.v.len() % self.chunk_size;
-            let n = if rem > 0 { n + 1 } else { n };
+            let n = self.v.len().div_ceil(self.chunk_size);
             (n, Some(n))
         }
     }
@@ -1613,7 +1606,7 @@ impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
             None
         } else {
             let start = (len - 1 - n) * self.chunk_size;
-            let end = (start + self.chunk_size).min(self.v.len());
+            let end = start + (self.v.len() - start).min(self.chunk_size);
             let nth_back = &self.v[start..end];
             self.v = &self.v[..start];
             Some(nth_back)
@@ -1702,9 +1695,7 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
         if self.v.is_empty() {
             (0, Some(0))
         } else {
-            let n = self.v.len() / self.chunk_size;
-            let rem = self.v.len() % self.chunk_size;
-            let n = if rem > 0 { n + 1 } else { n };
+            let n = self.v.len().div_ceil(self.chunk_size);
             (n, Some(n))
         }
     }
@@ -1903,13 +1894,10 @@ impl<'a, T> Iterator for ChunksExact<'a, T> {
 
     #[inline]
     fn next(&mut self) -> Option<&'a [T]> {
-        if self.v.len() < self.chunk_size {
-            None
-        } else {
-            let (fst, snd) = self.v.split_at(self.chunk_size);
-            self.v = snd;
-            Some(fst)
-        }
+        self.v.split_at_checked(self.chunk_size).and_then(|(chunk, rest)| {
+            self.v = rest;
+            Some(chunk)
+        })
     }
 
     #[inline]
@@ -1925,14 +1913,14 @@ impl<'a, T> Iterator for ChunksExact<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let (start, overflow) = n.overflowing_mul(self.chunk_size);
-        if start >= self.v.len() || overflow {
+        if let Some(start) = n.checked_mul(self.chunk_size)
+            && start < self.v.len()
+        {
+            self.v = &self.v[start..];
+            self.next()
+        } else {
             self.v = &self.v[..0]; // cheaper than &[]
             None
-        } else {
-            let (_, snd) = self.v.split_at(start);
-            self.v = snd;
-            self.next()
         }
     }
 
@@ -2061,15 +2049,11 @@ impl<'a, T> Iterator for ChunksExactMut<'a, T> {
 
     #[inline]
     fn next(&mut self) -> Option<&'a mut [T]> {
-        if self.v.len() < self.chunk_size {
-            None
-        } else {
-            // SAFETY: self.chunk_size is inbounds because we compared above against self.v.len()
-            let (head, tail) = unsafe { self.v.split_at_mut(self.chunk_size) };
-            self.v = tail;
-            // SAFETY: Nothing else points to or will point to the contents of this slice.
-            Some(unsafe { &mut *head })
-        }
+        // SAFETY: we have `&mut self`, so are allowed to temporarily materialize a mut slice
+        unsafe { &mut *self.v }.split_at_mut_checked(self.chunk_size).and_then(|(chunk, rest)| {
+            self.v = rest;
+            Some(chunk)
+        })
     }
 
     #[inline]
@@ -2085,15 +2069,15 @@ impl<'a, T> Iterator for ChunksExactMut<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
-        let (start, overflow) = n.overflowing_mul(self.chunk_size);
-        if start >= self.v.len() || overflow {
+        if let Some(start) = n.checked_mul(self.chunk_size)
+            && start < self.v.len()
+        {
+            // SAFETY: `start < self.v.len()`
+            self.v = unsafe { self.v.split_at_mut(start).1 };
+            self.next()
+        } else {
             self.v = &mut [];
             None
-        } else {
-            // SAFETY: The self.v contract ensures that any split_at_mut is valid.
-            let (_, snd) = unsafe { self.v.split_at_mut(start) };
-            self.v = snd;
-            self.next()
         }
     }
 
@@ -2341,9 +2325,7 @@ impl<'a, T> Iterator for RChunks<'a, T> {
         if self.v.is_empty() {
             (0, Some(0))
         } else {
-            let n = self.v.len() / self.chunk_size;
-            let rem = self.v.len() % self.chunk_size;
-            let n = if rem > 0 { n + 1 } else { n };
+            let n = self.v.len().div_ceil(self.chunk_size);
             (n, Some(n))
         }
     }
@@ -2355,17 +2337,17 @@ impl<'a, T> Iterator for RChunks<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let (end, overflow) = n.overflowing_mul(self.chunk_size);
-        if end >= self.v.len() || overflow {
+        if let Some(end) = n.checked_mul(self.chunk_size)
+            && end < self.v.len()
+        {
+            let end = self.v.len() - end;
+            let rest = &self.v[..end];
+            let (rest, chunk) = rest.split_at(end.saturating_sub(self.chunk_size));
+            self.v = rest;
+            Some(chunk)
+        } else {
             self.v = &self.v[..0]; // cheaper than &[]
             None
-        } else {
-            // Can't underflow because of the check above
-            let end = self.v.len() - end;
-            let start = end.saturating_sub(self.chunk_size);
-            let nth = &self.v[start..end];
-            self.v = &self.v[0..start];
-            Some(nth)
         }
     }
 
@@ -2508,9 +2490,7 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
         if self.v.is_empty() {
             (0, Some(0))
         } else {
-            let n = self.v.len() / self.chunk_size;
-            let rem = self.v.len() % self.chunk_size;
-            let n = if rem > 0 { n + 1 } else { n };
+            let n = self.v.len().div_ceil(self.chunk_size);
             (n, Some(n))
         }
     }
diff --git a/library/coretests/tests/slice.rs b/library/coretests/tests/slice.rs
index 110c4e5f3b406..6f60f71e8a477 100644
--- a/library/coretests/tests/slice.rs
+++ b/library/coretests/tests/slice.rs
@@ -432,6 +432,13 @@ fn test_chunks_exact_mut_zip_aliasing() {
     assert_eq!(first, (&mut [0, 1][..], &[6, 7][..]));
 }
 
+#[test]
+fn test_chunks_zst() {
+    const SIZE: usize = 16;
+    let mut it = [(); usize::MAX].chunks(SIZE);
+    assert_eq!(it.nth_back(0), Some(&[(); SIZE - 1][..]));
+}
+
 #[test]
 fn test_rchunks_mut_zip_aliasing() {
     let v1: &mut [i32] = &mut [0, 1, 2, 3, 4];

From b60788e90534fdb6581ba2d8691ee636baf1981f Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Tue, 4 Nov 2025 07:39:34 +0000
Subject: [PATCH 5/8] slice iter: rm all overflowing_* and switch conditions to
 mv dependent code close

---
 library/core/src/slice/iter.rs | 136 ++++++++++++++++-----------------
 1 file changed, 64 insertions(+), 72 deletions(-)

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 925910400eade..8e972fefbe82f 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -1601,15 +1601,15 @@ impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &self.v[..0]; // cheaper than &[]
-            None
-        } else {
+        if n < len {
             let start = (len - 1 - n) * self.chunk_size;
             let end = start + (self.v.len() - start).min(self.chunk_size);
             let nth_back = &self.v[start..end];
             self.v = &self.v[..start];
             Some(nth_back)
+        } else {
+            self.v = &self.v[..0]; // cheaper than &[]
+            None
         }
     }
 }
@@ -1770,10 +1770,7 @@ impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &mut [];
-            None
-        } else {
+        if n < len {
             let start = (len - 1 - n) * self.chunk_size;
             let end = match start.checked_add(self.chunk_size) {
                 Some(res) => cmp::min(self.v.len(), res),
@@ -1786,6 +1783,9 @@ impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
             self.v = head;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
             Some(unsafe { &mut *nth_back })
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 }
@@ -1952,15 +1952,15 @@ impl<'a, T> DoubleEndedIterator for ChunksExact<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &self.v[..0]; // cheaper than &[]
-            None
-        } else {
+        if n < len {
             let start = (len - 1 - n) * self.chunk_size;
             let end = start + self.chunk_size;
             let nth_back = &self.v[start..end];
             self.v = &self.v[..start];
             Some(nth_back)
+        } else {
+            self.v = &self.v[..0]; // cheaper than &[]
+            None
         }
     }
 }
@@ -2111,10 +2111,7 @@ impl<'a, T> DoubleEndedIterator for ChunksExactMut<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &mut [];
-            None
-        } else {
+        if n < len {
             let start = (len - 1 - n) * self.chunk_size;
             let end = start + self.chunk_size;
             // SAFETY: The self.v contract ensures that any split_at_mut is valid.
@@ -2124,6 +2121,9 @@ impl<'a, T> DoubleEndedIterator for ChunksExactMut<'a, T> {
             self.v = head;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
             Some(unsafe { &mut *nth_back })
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 }
@@ -2307,16 +2307,12 @@ impl<'a, T> Iterator for RChunks<'a, T> {
         if self.v.is_empty() {
             None
         } else {
-            let len = self.v.len();
-            let chunksz = cmp::min(len, self.chunk_size);
-            // SAFETY: split_at_unchecked just requires the argument be less
-            // than the length. This could only happen if the expression `len -
-            // chunksz` overflows. This could only happen if `chunksz > len`,
-            // which is impossible as we initialize it as the `min` of `len` and
-            // `self.chunk_size`.
-            let (fst, snd) = unsafe { self.v.split_at_unchecked(len - chunksz) };
-            self.v = fst;
-            Some(snd)
+            let idx = self.v.len().saturating_sub(self.chunk_size);
+            // SAFETY: self.chunk_size() > 0, so 0 <= idx < self.v.len().
+            // Thus `idx` is in-bounds for `self.v` and can be used as a valid argument for `split_at_mut_unchecked`.
+            let (rest, chunk) = unsafe { self.v.split_at_unchecked(idx) };
+            self.v = rest;
+            Some(chunk)
         }
     }
 
@@ -2389,17 +2385,16 @@ impl<'a, T> DoubleEndedIterator for RChunks<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &self.v[..0]; // cheaper than &[]
-            None
-        } else {
-            // can't underflow because `n < len`
+        if n < len {
             let offset_from_end = (len - 1 - n) * self.chunk_size;
             let end = self.v.len() - offset_from_end;
             let start = end.saturating_sub(self.chunk_size);
             let nth_back = &self.v[start..end];
             self.v = &self.v[end..];
             Some(nth_back)
+        } else {
+            self.v = &self.v[..0]; // cheaper than &[]
+            None
         }
     }
 }
@@ -2471,17 +2466,13 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
         if self.v.is_empty() {
             None
         } else {
-            let sz = cmp::min(self.v.len(), self.chunk_size);
-            let len = self.v.len();
-            // SAFETY: split_at_mut_unchecked just requires the argument be less
-            // than the length. This could only happen if the expression
-            // `len - sz` overflows. This could only happen if `sz >
-            // len`, which is impossible as we initialize it as the `min` of
-            // `self.v.len()` (e.g. `len`) and `self.chunk_size`.
-            let (head, tail) = unsafe { self.v.split_at_mut_unchecked(len - sz) };
-            self.v = head;
+            let idx = self.v.len().saturating_sub(self.chunk_size);
+            // SAFETY: self.chunk_size() > 0, so 0 <= idx < self.v.len().
+            // Thus `idx` is in-bounds for `self.v` and can be used as a valid argument for `split_at_mut_unchecked`.
+            let (rest, chunk) = unsafe { self.v.split_at_mut_unchecked(idx) };
+            self.v = rest;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
-            Some(unsafe { &mut *tail })
+            Some(unsafe { &mut *chunk })
         }
     }
 
@@ -2502,12 +2493,9 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
-        let (end, overflow) = n.overflowing_mul(self.chunk_size);
-        if end >= self.v.len() || overflow {
-            self.v = &mut [];
-            None
-        } else {
-            // Can't underflow because of the check above
+        if let Some(end) = n.checked_mul(self.chunk_size)
+            && end < self.v.len()
+        {
             let end = self.v.len() - end;
             let start = match end.checked_sub(self.chunk_size) {
                 Some(sum) => sum,
@@ -2522,6 +2510,9 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
             self.v = head;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
             Some(unsafe { &mut *nth })
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 
@@ -2566,10 +2557,7 @@ impl<'a, T> DoubleEndedIterator for RChunksMut<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &mut [];
-            None
-        } else {
+        if n < len {
             // can't underflow because `n < len`
             let offset_from_end = (len - 1 - n) * self.chunk_size;
             let end = self.v.len() - offset_from_end;
@@ -2581,6 +2569,9 @@ impl<'a, T> DoubleEndedIterator for RChunksMut<'a, T> {
             self.v = tail;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
             Some(unsafe { &mut *nth_back })
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 }
@@ -2711,14 +2702,14 @@ impl<'a, T> Iterator for RChunksExact<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let (end, overflow) = n.overflowing_mul(self.chunk_size);
-        if end >= self.v.len() || overflow {
+        if let Some(end) = n.checked_mul(self.chunk_size)
+            && end < self.v.len()
+        {
+            self.v = &self.v[..self.v.len() - end];
+            self.next()
+        } else {
             self.v = &self.v[..0]; // cheaper than &[]
             None
-        } else {
-            let (fst, _) = self.v.split_at(self.v.len() - end);
-            self.v = fst;
-            self.next()
         }
     }
 
@@ -2751,10 +2742,7 @@ impl<'a, T> DoubleEndedIterator for RChunksExact<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &self.v[..0]; // cheaper than &[]
-            None
-        } else {
+        if n < len {
             // now that we know that `n` corresponds to a chunk,
             // none of these operations can underflow/overflow
             let offset = (len - n) * self.chunk_size;
@@ -2763,6 +2751,9 @@ impl<'a, T> DoubleEndedIterator for RChunksExact<'a, T> {
             let nth_back = &self.v[start..end];
             self.v = &self.v[end..];
             Some(nth_back)
+        } else {
+            self.v = &self.v[..0]; // cheaper than &[]
+            None
         }
     }
 }
@@ -2875,16 +2866,17 @@ impl<'a, T> Iterator for RChunksExactMut<'a, T> {
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
-        let (end, overflow) = n.overflowing_mul(self.chunk_size);
-        if end >= self.v.len() || overflow {
-            self.v = &mut [];
-            None
-        } else {
-            let len = self.v.len();
+        if let Some(end) = n.checked_mul(self.chunk_size)
+            && end < self.v.len()
+        {
+            let idx = self.v.len() - end;
             // SAFETY: The self.v contract ensures that any split_at_mut is valid.
-            let (fst, _) = unsafe { self.v.split_at_mut(len - end) };
+            let (fst, _) = unsafe { self.v.split_at_mut(idx) };
             self.v = fst;
             self.next()
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 
@@ -2919,10 +2911,7 @@ impl<'a, T> DoubleEndedIterator for RChunksExactMut<'a, T> {
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
         let len = self.len();
-        if n >= len {
-            self.v = &mut [];
-            None
-        } else {
+        if n < len {
             // now that we know that `n` corresponds to a chunk,
             // none of these operations can underflow/overflow
             let offset = (len - n) * self.chunk_size;
@@ -2935,6 +2924,9 @@ impl<'a, T> DoubleEndedIterator for RChunksExactMut<'a, T> {
             self.v = tail;
             // SAFETY: Nothing else points to or will point to the contents of this slice.
             Some(unsafe { &mut *nth_back })
+        } else {
+            self.v = &mut [];
+            None
         }
     }
 }

From 62e0a843c0453233c0ebdbe756939ab7511c1a9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jana=20D=C3=B6nszelmann?= <jana@donsz.nl>
Date: Mon, 1 Dec 2025 19:44:21 +0100
Subject: [PATCH 6/8] also introduce Peekable::next_if_map_mut next to
 next_if_map

---
 library/core/src/iter/adapters/peekable.rs | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/library/core/src/iter/adapters/peekable.rs b/library/core/src/iter/adapters/peekable.rs
index a55de75d56c6e..ee40d2b74c647 100644
--- a/library/core/src/iter/adapters/peekable.rs
+++ b/library/core/src/iter/adapters/peekable.rs
@@ -331,6 +331,8 @@ impl<I: Iterator> Peekable<I> {
     /// If the closure panics, the next value will always be consumed and dropped
     /// even if the panic is caught, because the closure never returned an `Err` value to put back.
     ///
+    /// See also: [`next_if_map_mut`](Self::next_if_map_mut).
+    ///
     /// # Examples
     ///
     /// Parse the leading decimal number from an iterator of characters.
@@ -419,6 +421,44 @@ impl<I: Iterator> Peekable<I> {
         self.peeked = Some(unpeek);
         None
     }
+
+    /// Gives a mutable reference to the next value of the iterator and applies a function `f` to it,
+    /// returning the result and advancing the iterator if `f` returns `Some`.
+    ///
+    /// Otherwise, if `f` returns `None`, the next value is kept for the next iteration.
+    ///
+    /// If `f` panics, the item that is consumed from the iterator as if `Some` was returned from `f`.
+    /// The value will be dropped.
+    ///
+    /// This is similar to [`next_if_map`](Self::next_if_map), except ownership of the item is not given to `f`.
+    /// This can be preferable if `f` would copy the item anyway.
+    ///
+    /// # Examples
+    ///
+    /// Parse the leading decimal number from an iterator of characters.
+    /// ```
+    /// #![feature(peekable_next_if_map)]
+    /// let mut iter = "125 GOTO 10".chars().peekable();
+    /// let mut line_num = 0_u32;
+    /// while let Some(digit) = iter.next_if_map_mut(|c| c.to_digit(10)) {
+    ///     line_num = line_num * 10 + digit;
+    /// }
+    /// assert_eq!(line_num, 125);
+    /// assert_eq!(iter.collect::<String>(), " GOTO 10");
+    /// ```
+    #[unstable(feature = "peekable_next_if_map", issue = "143702")]
+    pub fn next_if_map_mut<R>(&mut self, f: impl FnOnce(&mut I::Item) -> Option<R>) -> Option<R> {
+        let unpeek = if let Some(mut item) = self.next() {
+            match f(&mut item) {
+                Some(result) => return Some(result),
+                None => Some(item),
+            }
+        } else {
+            None
+        };
+        self.peeked = Some(unpeek);
+        None
+    }
 }
 
 #[unstable(feature = "trusted_len", issue = "37572")]

From 1331c35f0279fb11266003d9859c0bd30216e07b Mon Sep 17 00:00:00 2001
From: Ayush Singh <ayush@beagleboard.org>
Date: Tue, 2 Dec 2025 13:56:48 +0530
Subject: [PATCH 7/8] std: sys: fs: uefi: Make time in FileAttr optional

At least on OVMF, some files copied over from linux file system seem
to have invalid time (year = 1980 and everything else 0). Since Rust
allows time to be optional and we can return error, that seems to be
the way to go for now.

Signed-off-by: Ayush Singh <ayush@beagleboard.org>
---
 library/std/src/sys/fs/uefi.rs       | 28 +++++++------
 library/std/src/sys/pal/uefi/time.rs | 59 ++++++++++++++++------------
 2 files changed, 50 insertions(+), 37 deletions(-)

diff --git a/library/std/src/sys/fs/uefi.rs b/library/std/src/sys/fs/uefi.rs
index bd4ae56974f0c..44f8b6e80f903 100644
--- a/library/std/src/sys/fs/uefi.rs
+++ b/library/std/src/sys/fs/uefi.rs
@@ -18,9 +18,8 @@ pub struct File(!);
 pub struct FileAttr {
     attr: u64,
     size: u64,
-    accessed: SystemTime,
-    modified: SystemTime,
-    created: SystemTime,
+    file_time: FileTimes,
+    created: Option<SystemTime>,
 }
 
 pub struct ReadDir(!);
@@ -66,15 +65,20 @@ impl FileAttr {
     }
 
     pub fn modified(&self) -> io::Result<SystemTime> {
-        Ok(self.modified)
+        self.file_time
+            .modified
+            .ok_or(io::const_error!(io::ErrorKind::InvalidData, "modification time is not valid"))
     }
 
     pub fn accessed(&self) -> io::Result<SystemTime> {
-        Ok(self.accessed)
+        self.file_time
+            .accessed
+            .ok_or(io::const_error!(io::ErrorKind::InvalidData, "last access time is not valid"))
     }
 
     pub fn created(&self) -> io::Result<SystemTime> {
-        Ok(self.created)
+        self.created
+            .ok_or(io::const_error!(io::ErrorKind::InvalidData, "creation time is not valid"))
     }
 
     fn from_uefi(info: helpers::UefiBox<file::Info>) -> Self {
@@ -82,8 +86,10 @@ impl FileAttr {
             Self {
                 attr: (*info.as_ptr()).attribute,
                 size: (*info.as_ptr()).file_size,
-                modified: uefi_fs::uefi_to_systemtime((*info.as_ptr()).modification_time),
-                accessed: uefi_fs::uefi_to_systemtime((*info.as_ptr()).last_access_time),
+                file_time: FileTimes {
+                    modified: uefi_fs::uefi_to_systemtime((*info.as_ptr()).modification_time),
+                    accessed: uefi_fs::uefi_to_systemtime((*info.as_ptr()).last_access_time),
+                },
                 created: uefi_fs::uefi_to_systemtime((*info.as_ptr()).create_time),
             }
         }
@@ -627,9 +633,9 @@ mod uefi_fs {
 
     /// EDK2 FAT driver uses EFI_UNSPECIFIED_TIMEZONE to represent localtime. So for proper
     /// conversion to SystemTime, we use the current time to get the timezone in such cases.
-    pub(crate) fn uefi_to_systemtime(mut time: r_efi::efi::Time) -> SystemTime {
+    pub(crate) fn uefi_to_systemtime(mut time: r_efi::efi::Time) -> Option<SystemTime> {
         time.timezone = if time.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE {
-            time::system_time_internal::now().unwrap().timezone
+            time::system_time_internal::now().timezone
         } else {
             time.timezone
         };
@@ -639,7 +645,7 @@ mod uefi_fs {
     /// Convert to UEFI Time with the current timezone.
     #[expect(dead_code)]
     fn systemtime_to_uefi(time: SystemTime) -> r_efi::efi::Time {
-        let now = time::system_time_internal::now().unwrap();
+        let now = time::system_time_internal::now();
         time.to_uefi_loose(now.timezone, now.daylight)
     }
 }
diff --git a/library/std/src/sys/pal/uefi/time.rs b/library/std/src/sys/pal/uefi/time.rs
index f9f90a454976a..28dacbe3068a7 100644
--- a/library/std/src/sys/pal/uefi/time.rs
+++ b/library/std/src/sys/pal/uefi/time.rs
@@ -24,7 +24,8 @@ pub const UNIX_EPOCH: SystemTime = SystemTime::from_uefi(r_efi::efi::Time {
     daylight: 0,
     pad1: 0,
     pad2: 0,
-});
+})
+.unwrap();
 
 const MAX_UEFI_TIME: SystemTime = SystemTime::from_uefi(r_efi::efi::Time {
     year: 9999,
@@ -38,7 +39,8 @@ const MAX_UEFI_TIME: SystemTime = SystemTime::from_uefi(r_efi::efi::Time {
     daylight: 0,
     pad1: 0,
     pad2: 0,
-});
+})
+.unwrap();
 
 impl Instant {
     pub fn now() -> Instant {
@@ -68,8 +70,11 @@ impl Instant {
 }
 
 impl SystemTime {
-    pub(crate) const fn from_uefi(t: r_efi::efi::Time) -> Self {
-        Self(system_time_internal::from_uefi(&t))
+    pub(crate) const fn from_uefi(t: r_efi::efi::Time) -> Option<Self> {
+        match system_time_internal::from_uefi(&t) {
+            Some(x) => Some(Self(x)),
+            None => None,
+        }
     }
 
     pub(crate) const fn to_uefi(
@@ -96,9 +101,8 @@ impl SystemTime {
     }
 
     pub fn now() -> SystemTime {
-        system_time_internal::now()
-            .map(Self::from_uefi)
-            .unwrap_or_else(|| panic!("time not implemented on this platform"))
+        Self::from_uefi(system_time_internal::now())
+            .expect("time incorrectly implemented on this platform")
     }
 
     pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
@@ -129,17 +133,18 @@ pub(crate) mod system_time_internal {
     const SECS_IN_DAY: u64 = SECS_IN_HOUR * 24;
     const SYSTEMTIME_TIMEZONE: i64 = -1440 * SECS_IN_MINUTE as i64;
 
-    pub(crate) fn now() -> Option<Time> {
-        let runtime_services: NonNull<RuntimeServices> = helpers::runtime_services()?;
+    pub(crate) fn now() -> Time {
+        let runtime_services: NonNull<RuntimeServices> =
+            helpers::runtime_services().expect("Runtime services are not available");
         let mut t: MaybeUninit<Time> = MaybeUninit::uninit();
         let r = unsafe {
             ((*runtime_services.as_ptr()).get_time)(t.as_mut_ptr(), crate::ptr::null_mut())
         };
         if r.is_error() {
-            return None;
+            panic!("time not implemented on this platform");
         }
 
-        Some(unsafe { t.assume_init() })
+        unsafe { t.assume_init() }
     }
 
     /// This algorithm is a modified form of the one described in the post
@@ -147,20 +152,22 @@ pub(crate) mod system_time_internal {
     ///
     /// The changes are to use 1900-01-01-00:00:00 with timezone -1440 as anchor instead of UNIX
     /// epoch used in the original algorithm.
-    pub(crate) const fn from_uefi(t: &Time) -> Duration {
-        assert!(t.month <= 12 && t.month != 0);
-        assert!(t.year >= 1900 && t.year <= 9999);
-        assert!(t.day <= 31 && t.day != 0);
-
-        assert!(t.second < 60);
-        assert!(t.minute < 60);
-        assert!(t.hour < 24);
-        assert!(t.nanosecond < 1_000_000_000);
-
-        assert!(
-            (t.timezone <= 1440 && t.timezone >= -1440)
-                || t.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE
-        );
+    pub(crate) const fn from_uefi(t: &Time) -> Option<Duration> {
+        if !(t.month <= 12
+            && t.month != 0
+            && t.year >= 1900
+            && t.year <= 9999
+            && t.day <= 31
+            && t.day != 0
+            && t.second < 60
+            && t.minute <= 60
+            && t.hour < 24
+            && t.nanosecond < 1_000_000_000
+            && ((t.timezone <= 1440 && t.timezone >= -1440)
+                || t.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE))
+        {
+            return None;
+        }
 
         const YEAR_BASE: u32 = 4800; /* Before min year, multiple of 400. */
 
@@ -188,7 +195,7 @@ pub(crate) mod system_time_internal {
         // Calculate the offset from 1/1/1900 at timezone -1440 min
         let epoch = localtime_epoch.checked_add_signed(normalized_timezone).unwrap();
 
-        Duration::new(epoch, t.nanosecond)
+        Some(Duration::new(epoch, t.nanosecond))
     }
 
     /// This algorithm is a modified version of the one described in the post:

From 4b000cfacd7020330e613a2a27564401611b0f12 Mon Sep 17 00:00:00 2001
From: xonx4l <sk797119@gmail.com>
Date: Sat, 8 Nov 2025 00:11:35 +0530
Subject: [PATCH 8/8] Merge E0412 into E0425

---
 .../src/error_codes/E0412.md                  |  6 +-
 compiler/rustc_resolve/src/late.rs            |  8 +-
 .../rustc_resolve/src/late/diagnostics.rs     |  4 +-
 .../clippy/tests/ui/crashes/ice-6252.stderr   |  6 +-
 tests/rustdoc-ui/impl-fn-nesting.stderr       | 10 +--
 tests/ui/annotate-snippet/missing-type.stderr |  4 +-
 .../extern-fn-arg-names.stderr                |  4 +-
 tests/ui/argument-suggestions/issue-109831.rs |  2 +-
 .../argument-suggestions/issue-109831.stderr  |  4 +-
 tests/ui/asm/issue-113788.rs                  |  2 +-
 tests/ui/asm/issue-113788.stderr              |  4 +-
 tests/ui/associated-consts/issue-93835.stderr |  4 +-
 .../return-type-notation/not-a-method.stderr  |  6 +-
 .../associated-types-eq-1.stderr              |  4 +-
 .../in-trait/return-not-existing-pair.rs      |  2 +-
 .../in-trait/return-not-existing-pair.stderr  |  4 +-
 ...eturn-not-existing-type-wrapping-rpitit.rs |  2 +-
 ...n-not-existing-type-wrapping-rpitit.stderr |  4 +-
 .../issue-72590-type-error-sized.stderr       |  6 +-
 .../unconstrained-lifetimes.stderr            |  4 +-
 .../attributes/align-on-fields-143987.stderr  |  4 +-
 .../ui/borrowck/bad-drop-side-effects.stderr  |  4 +-
 tests/ui/c-variadic/issue-86053-1.stderr      |  4 +-
 tests/ui/cast/casts-issue-46365.stderr        |  4 +-
 .../ice-cast-type-with-error-124848.stderr    |  4 +-
 tests/ui/closures/issue-78720.stderr          |  4 +-
 tests/ui/closures/issue-90871.stderr          |  4 +-
 .../cmse-nonsecure-call/generics.stderr       |  4 +-
 tests/ui/coercion/type-errors.stderr          |  8 +-
 .../coherence/coherence-error-suppression.rs  |  2 +-
 .../coherence-error-suppression.stderr        |  4 +-
 .../illegal-copy-bad-projection.stderr        |  4 +-
 ...ence-error-for-undefined-type-18058.stderr |  4 +-
 .../ui-testing-optout.stderr                  |  8 +-
 ...const_arg_trivial_macro_expansion-2.stderr |  5 +-
 .../early/invalid-const-arguments.stderr      |  8 +-
 ...e-a-closure-or-coroutine-ice-113776.stderr |  4 +-
 ...es-of-no-entry-found-for-key-119275.stderr |  4 +-
 .../unevaluated-const-ice-119731.stderr       |  8 +-
 .../mgca/projection-error.stderr              |  6 +-
 ...arent_generics_of_nested_in_default.stderr |  5 +-
 ...ion-error-with-const-generics-77919.stderr |  6 +-
 .../const-generics/type_not_in_scope.stderr   |  4 +-
 tests/ui/const-generics/unknown_adt.stderr    |  4 +-
 ...e-type-mismatch-when-copying-112824.stderr |  4 +-
 ...rroneous_type_in_const_return_value.stderr |  4 +-
 .../consts/erroneous_type_in_promoted.stderr  |  4 +-
 tests/ui/consts/error-is-freeze.stderr        |  4 +-
 .../ice-bad-input-type-for-cast-83056.stderr  |  4 +-
 ...ssue-56028-there-is-an-enum-variant.stderr |  5 +-
 ...gg-stable-import-first-issue-140240.stderr |  4 +-
 tests/ui/dropck/drop-on-non-struct.stderr     |  4 +-
 .../erroneous_signature.stderr                |  6 +-
 .../ice-from-type-error-issue-148515.stderr   |  8 +-
 tests/ui/error-codes/E0412.rs                 |  2 +-
 tests/ui/error-codes/E0412.stderr             |  4 +-
 ...extern-item-where-clauses-debug-ice.stderr |  8 +-
 tests/ui/fn/trait-fn-generic-mismatch.stderr  |  4 +-
 ...lp-with-err-generic-is-not-function.stderr |  6 +-
 .../equality-bound.stderr                     | 16 ++--
 tests/ui/hygiene/arguments.stderr             |  4 +-
 tests/ui/hygiene/generate-mod.stderr          | 14 ++--
 ...rpitits-are-created-before-freezing.stderr |  4 +-
 .../ui/impl-trait/in-trait/refine-err.stderr  |  4 +-
 .../rpitit-shadowed-by-missing-adt.stderr     |  4 +-
 tests/ui/impl-trait/issues/issue-54966.stderr |  4 +-
 .../opaque-used-in-extraneous-argument.stderr |  6 +-
 tests/ui/implied-bounds/references-err.stderr |  4 +-
 .../glob-conflict-cross-crate-2.stderr        |  4 +-
 tests/ui/imports/glob-resolve1.stderr         | 10 +--
 ...port-alias-issue-121168.edition2015.stderr |  4 +-
 ...port-alias-issue-121168.edition2018.stderr |  4 +-
 ...port-alias-issue-121168.edition2021.stderr |  4 +-
 .../imports/inaccessible_type_aliases.stderr  |  6 +-
 tests/ui/imports/issue-4366-2.stderr          |  6 +-
 tests/ui/issues/issue-30589.stderr            |  4 +-
 tests/ui/issues/issue-36836.stderr            |  4 +-
 ...annot-transmute-unnormalizable-type.stderr |  6 +-
 tests/ui/layout/issue-84108.stderr            |  6 +-
 .../malformed-unsized-type-in-union.stderr    |  6 +-
 .../layout/thaw-transmute-invalid-enum.stderr |  6 +-
 .../layout/transmute-to-tail-with-err.stderr  |  6 +-
 ...elided-lifetime-in-const-param-type.stderr |  6 +-
 .../issue-83907-invalid-fn-like-path.stderr   |  4 +-
 tests/ui/lint/issue-35075.stderr              |  6 +-
 tests/ui/lint/recommend-literal.rs            |  4 +-
 tests/ui/lint/recommend-literal.stderr        | 20 ++---
 tests/ui/lint/use_suggestion_json.stderr      | 80 +++++++++----------
 tests/ui/macros/macro-context.stderr          |  5 +-
 tests/ui/match/issue-82866.stderr             |  5 +-
 .../mir/gvn-nonsensical-coroutine-layout.rs   |  2 +-
 .../gvn-nonsensical-coroutine-layout.stderr   |  6 +-
 ...ue-83499-input-output-iteration-ice.stderr |  4 +-
 tests/ui/mir/meaningless-bound.stderr         |  4 +-
 ...d-2021-closure-capture-ice-110453-1.stderr |  4 +-
 ...d-2021-closure-capture-ice-110453-2.stderr |  4 +-
 .../missing-type-parameter2.stderr            | 14 ++--
 tests/ui/offset-of/offset-of-enum.stderr      |  6 +-
 tests/ui/offset-of/offset-of-self.stderr      |  4 +-
 .../ty-variance-issue-124423.stderr           |  6 +-
 tests/ui/parser/associated-path-shl.stderr    | 12 +--
 ...-param-decl-on-type-instead-of-impl.stderr |  4 +-
 .../ui/parser/dyn-trait-compatibility.stderr  | 14 ++--
 .../ui/parser/fn-field-parse-error-ice.stderr |  4 +-
 .../recover-fn-ptr-with-generics.stderr       |  6 +-
 tests/ui/parser/unmatched-langle-1.rs         |  2 +-
 tests/ui/parser/unmatched-langle-1.stderr     |  5 +-
 tests/ui/parser/where_with_bound.stderr       |  4 +-
 .../issue-119493-type-error-ice.stderr        |  8 +-
 tests/ui/privacy/privacy-ns1.stderr           |  6 +-
 .../ui/privacy/sysroot-private.default.stderr |  4 +-
 ...sroot-private.rustc_private_enabled.stderr |  4 +-
 .../attributes-on-modules-fail.stderr         |  8 +-
 tests/ui/proc-macro/empty-where-clause.stderr |  8 +-
 tests/ui/proc-macro/generate-mod.stderr       | 10 +--
 tests/ui/proc-macro/issue-83510.stderr        |  4 +-
 tests/ui/proc-macro/macro-rules-derive.stderr |  4 +-
 tests/ui/proc-macro/mixed-site-span.stderr    |  6 +-
 .../ui/proc-macro/span-from-proc-macro.stderr |  6 +-
 tests/ui/recursion/recursive-reexports.stderr |  4 +-
 tests/ui/regions/outlives-with-missing.stderr |  4 +-
 .../dont-compute-arg-names-for-non-fn.stderr  |  4 +-
 .../resolve/editions-crate-root-2015.stderr   |  8 +-
 .../resolve/editions-crate-root-2018.stderr   |  8 +-
 tests/ui/resolve/issue-21221-1.rs             |  2 +-
 tests/ui/resolve/issue-21221-1.stderr         |  4 +-
 tests/ui/resolve/issue-35675.stderr           |  8 +-
 .../issue-69401-trait-fn-no-body-ty-local.rs  |  2 +-
 ...sue-69401-trait-fn-no-body-ty-local.stderr |  4 +-
 tests/ui/resolve/issue-85348.rs               |  2 +-
 tests/ui/resolve/issue-85348.stderr           |  4 +-
 tests/ui/resolve/issue-88472.rs               |  4 +-
 tests/ui/resolve/issue-88472.stderr           |  6 +-
 tests/ui/resolve/levenshtein.stderr           | 13 ++-
 .../missing-type-in-scope-58712.stderr        |  6 +-
 tests/ui/resolve/privacy-enum-ctor.stderr     | 10 +--
 tests/ui/resolve/raw-ident-in-path.stderr     |  4 +-
 .../resolve/resolve-assoc-suggestions.stderr  | 10 +--
 .../resolve/resolve-primitive-fallback.stderr |  4 +-
 ...e-with-name-similar-to-struct-field.stderr |  5 +-
 tests/ui/resolve/use_suggestion.stderr        |  8 +-
 .../resolve/use_suggestion_placement.stderr   |  7 +-
 tests/ui/self/elision/nested-item.stderr      |  4 +-
 ...s-in-pattern-with-ty-err-doesnt-ice.stderr |  4 +-
 ...incompatible-closure-captures-96258.stderr |  6 +-
 .../issue-68830-spurious-diagnostics.stderr   |  4 +-
 .../impl-on-nonexisting.stderr                |  4 +-
 ...ce-struct-tail-normalization-113272.stderr |  4 +-
 .../assoc-type-in-method-return.stderr        |  4 +-
 .../dont-suggest-foreign-doc-hidden.rs        |  8 +-
 .../dont-suggest-foreign-doc-hidden.stderr    | 10 +--
 .../no-extern-crate-in-type.stderr            |  4 +-
 .../type-not-found-in-adt-field.stderr        |  6 +-
 ...ice-unsized-struct-arg-issue-121612.stderr |  6 +-
 .../impl-bound-with-references-error.rs       |  2 +-
 .../impl-bound-with-references-error.stderr   |  4 +-
 ...icate-generic-parameter-error-86756.stderr |  4 +-
 .../error-reporting/apit-with-bad-path.stderr |  4 +-
 .../where-clause-with-bad-path.stderr         |  4 +-
 tests/ui/traits/ignore-err-impls.stderr       |  4 +-
 tests/ui/traits/issue-50480.stderr            | 14 ++--
 tests/ui/traits/issue-75627.stderr            |  4 +-
 tests/ui/traits/issue-78372.stderr            |  8 +-
 .../dont-normalize-proj-with-error.stderr     |  4 +-
 .../issue-118950-root-region.stderr           |  4 +-
 .../binder-defaults-112547.stderr             |  4 +-
 .../binder-defaults-118697.stderr             |  4 +-
 .../traits/trait-selection-ice-84727.stderr   | 10 +--
 .../ui/transmutability/issue-101739-1.stderr  |  4 +-
 .../unknown_dst.stderr                        |  4 +-
 .../unknown_dst_field.stderr                  |  6 +-
 .../unknown_src.stderr                        |  4 +-
 .../unknown_src_field.stderr                  |  6 +-
 .../ui/tuple/tuple-struct-fields/test.stderr  |  4 +-
 .../ui/tuple/tuple-struct-fields/test2.stderr |  6 +-
 .../ui/tuple/tuple-struct-fields/test3.stderr |  6 +-
 .../define_opaques_attr/invalid_path.stderr   |  4 +-
 .../nested-impl-trait-in-tait.stderr          |  4 +-
 .../cannot-find-wrapper-with-impl-trait.rs    |  2 +-
 ...cannot-find-wrapper-with-impl-trait.stderr |  4 +-
 tests/ui/type/issue-7607-1.stderr             |  4 +-
 tests/ui/type/type-path-err-node-types.stderr |  4 +-
 .../typeck/apit-with-error-type-in-sig.stderr |  4 +-
 .../autoderef-with-param-env-error.stderr     |  4 +-
 ...mpl-for-nonexistent-type-error-8767.stderr |  4 +-
 tests/ui/typeck/issue-104510-ice.stderr       |  4 +-
 tests/ui/typeck/issue-83693.rs                |  6 +-
 tests/ui/typeck/issue-83693.stderr            |  8 +-
 tests/ui/typeck/issue-88844.rs                |  2 +-
 tests/ui/typeck/issue-88844.stderr            |  4 +-
 tests/ui/typeck/issue-90319.rs                |  2 +-
 tests/ui/typeck/issue-90319.stderr            |  4 +-
 tests/ui/typeck/issue-91267.rs                |  2 +-
 tests/ui/typeck/issue-91267.stderr            |  4 +-
 .../nonexistent-field-not-ambiguous.stderr    |  4 +-
 ...ugg-swap-equality-in-macro-issue-139050.rs |  2 +-
 ...swap-equality-in-macro-issue-139050.stderr |  4 +-
 .../union/unresolved-field-isnt-copy.stderr   |  4 +-
 ...type-resolve-error-two-structs-deep.stderr |  4 +-
 tests/ui/wf/issue-110157.stderr               |  6 +-
 .../where-clauses/ignore-err-clauses.stderr   |  4 +-
 .../normalization-of-unknown-type.stderr      |  4 +-
 202 files changed, 557 insertions(+), 570 deletions(-)

diff --git a/compiler/rustc_error_codes/src/error_codes/E0412.md b/compiler/rustc_error_codes/src/error_codes/E0412.md
index d9ebc852bbab7..a8adcbc57986c 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0412.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0412.md
@@ -1,8 +1,8 @@
-A used type name is not in scope.
+#### Note: this error code is no longer emitted by the compiler.
 
 Erroneous code examples:
 
-```compile_fail,E0412
+```compile_fail,E0425
 impl Something {} // error: type name `Something` is not in scope
 
 // or:
@@ -42,7 +42,7 @@ module. To fix this, you can follow the suggestion and use File directly or
 `use super::File;` which will import the types from the parent namespace. An
 example that causes this error is below:
 
-```compile_fail,E0412
+```compile_fail,E0425
 use std::fs::File;
 
 mod foo {
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index df620ddb66529..1c95a0c200af1 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -622,7 +622,7 @@ impl PathSource<'_, '_, '_> {
             (PathSource::Trait(_), true) => E0404,
             (PathSource::Trait(_), false) => E0405,
             (PathSource::Type | PathSource::DefineOpaques, true) => E0573,
-            (PathSource::Type | PathSource::DefineOpaques, false) => E0412,
+            (PathSource::Type | PathSource::DefineOpaques, false) => E0425,
             (PathSource::Struct(_), true) => E0574,
             (PathSource::Struct(_), false) => E0422,
             (PathSource::Expr(..), true) | (PathSource::Delegation, true) => E0423,
@@ -3158,7 +3158,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         result
     }
 
-    /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
+    /// When evaluating a `trait` use its associated types' idents for suggestions in E0425.
     fn resolve_trait_items(&mut self, trait_items: &'ast [Box<AssocItem>]) {
         let trait_assoc_items =
             replace(&mut self.diag_metadata.current_trait_assoc_items, Some(trait_items));
@@ -4359,7 +4359,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
 
                 // There are two different error messages user might receive at
                 // this point:
-                // - E0412 cannot find type `{}` in this scope
+                // - E0425 cannot find type `{}` in this scope
                 // - E0433 failed to resolve: use of undeclared type or module `{}`
                 //
                 // The first one is emitted for paths in type-position, and the
@@ -4367,7 +4367,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 //
                 // Thus (since we're in expression-position at this point), not to
                 // confuse the user, we want to keep the *message* from E0433 (so
-                // `parent_err`), but we want *hints* from E0412 (so `err`).
+                // `parent_err`), but we want *hints* from E0425 (so `err`).
                 //
                 // And that's what happens below - we're just mixing both messages
                 // into a single one.
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 08976ce4feea5..2b85639376d97 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -705,7 +705,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
             if !enum_candidates.is_empty() {
                 enum_candidates.sort();
 
-                // Contextualize for E0412 "cannot find type", but don't belabor the point
+                // Contextualize for E0425 "cannot find type", but don't belabor the point
                 // (that it's a variant) for E0573 "expected type, found variant".
                 let preamble = if res.is_none() {
                     let others = match enum_candidates.len() {
@@ -1135,7 +1135,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                 }
 
                 self.suggest_ident_hidden_by_hygiene(err, path, span);
-            } else if err_code == E0412 {
+                // cannot find type in this scope
                 if let Some(correct) = Self::likely_rust_type(path) {
                     err.span_suggestion(
                         span,
diff --git a/src/tools/clippy/tests/ui/crashes/ice-6252.stderr b/src/tools/clippy/tests/ui/crashes/ice-6252.stderr
index 201a897b23195..b6a2597a44d50 100644
--- a/src/tools/clippy/tests/ui/crashes/ice-6252.stderr
+++ b/src/tools/clippy/tests/ui/crashes/ice-6252.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `PhantomData` in this scope
+error[E0425]: cannot find type `PhantomData` in this scope
   --> tests/ui/crashes/ice-6252.rs:9:9
    |
 LL |     _n: PhantomData,
@@ -9,7 +9,7 @@ help: consider importing this struct
 LL + use std::marker::PhantomData;
    |
 
-error[E0412]: cannot find type `VAL` in this scope
+error[E0425]: cannot find type `VAL` in this scope
   --> tests/ui/crashes/ice-6252.rs:12:63
    |
 LL | impl<N, M> TypeVal<usize> for Multiply<N, M> where N: TypeVal<VAL> {}
@@ -31,5 +31,5 @@ LL | impl<N, M> TypeVal<usize> for Multiply<N, M> where N: TypeVal<VAL> {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0046, E0412.
+Some errors have detailed explanations: E0046, E0425.
 For more information about an error, try `rustc --explain E0046`.
diff --git a/tests/rustdoc-ui/impl-fn-nesting.stderr b/tests/rustdoc-ui/impl-fn-nesting.stderr
index 75e6b4ed217dd..42d09258a90d1 100644
--- a/tests/rustdoc-ui/impl-fn-nesting.stderr
+++ b/tests/rustdoc-ui/impl-fn-nesting.stderr
@@ -10,7 +10,7 @@ error[E0405]: cannot find trait `UnknownBound` in this scope
 LL | pub fn f<B: UnknownBound>(a: UnknownType, b: B) {
    |             ^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `UnknownType` in this scope
+error[E0425]: cannot find type `UnknownType` in this scope
   --> $DIR/impl-fn-nesting.rs:11:30
    |
 LL | pub fn f<B: UnknownBound>(a: UnknownType, b: B) {
@@ -34,7 +34,7 @@ error[E0405]: cannot find trait `UnknownBound` in this scope
 LL |     impl<T: UnknownBound> UnknownTrait for T {}
    |             ^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `UnknownType` in this scope
+error[E0425]: cannot find type `UnknownType` in this scope
   --> $DIR/impl-fn-nesting.rs:18:25
    |
 LL |     impl ValidTrait for UnknownType {}
@@ -46,13 +46,13 @@ error[E0405]: cannot find trait `UnknownBound` in this scope
 LL |     impl ValidTrait for ValidType where ValidTrait: UnknownBound {}
    |                                                     ^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `UnknownType` in this scope
+error[E0425]: cannot find type `UnknownType` in this scope
   --> $DIR/impl-fn-nesting.rs:25:21
    |
 LL |         type Item = UnknownType;
    |                     ^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `UnknownType` in this scope
+error[E0425]: cannot find type `UnknownType` in this scope
   --> $DIR/impl-fn-nesting.rs:44:37
    |
 LL |             pub fn doubly_nested(c: UnknownType) {
@@ -60,5 +60,5 @@ LL |             pub fn doubly_nested(c: UnknownType) {
 
 error: aborting due to 10 previous errors
 
-Some errors have detailed explanations: E0405, E0412.
+Some errors have detailed explanations: E0405, E0425.
 For more information about an error, try `rustc --explain E0405`.
diff --git a/tests/ui/annotate-snippet/missing-type.stderr b/tests/ui/annotate-snippet/missing-type.stderr
index 0b8f323fdace8..ab02697a6980f 100644
--- a/tests/ui/annotate-snippet/missing-type.stderr
+++ b/tests/ui/annotate-snippet/missing-type.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Iter` in this scope
+error[E0425]: cannot find type `Iter` in this scope
   --> $DIR/missing-type.rs:5:12
    |
 LL |     let x: Iter;
@@ -18,4 +18,4 @@ LL + use std::collections::hash_map::Iter;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/argument-suggestions/extern-fn-arg-names.stderr b/tests/ui/argument-suggestions/extern-fn-arg-names.stderr
index 28500908e7ea3..e4183e6d519ef 100644
--- a/tests/ui/argument-suggestions/extern-fn-arg-names.stderr
+++ b/tests/ui/argument-suggestions/extern-fn-arg-names.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `err` in this scope
+error[E0425]: cannot find type `err` in this scope
   --> $DIR/extern-fn-arg-names.rs:2:29
    |
 LL |     fn dstfn(src: i32, dst: err);
@@ -22,5 +22,5 @@ LL |     dstfn(1, /* dst */);
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0061, E0412.
+Some errors have detailed explanations: E0061, E0425.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/argument-suggestions/issue-109831.rs b/tests/ui/argument-suggestions/issue-109831.rs
index 2e8ae40f63059..2a5eadd964246 100644
--- a/tests/ui/argument-suggestions/issue-109831.rs
+++ b/tests/ui/argument-suggestions/issue-109831.rs
@@ -1,7 +1,7 @@
 struct A;
 struct B;
 
-fn f(b1: B, b2: B, a2: C) {} //~ ERROR E0412
+fn f(b1: B, b2: B, a2: C) {} //~ ERROR E0425
 
 fn main() {
     f(A, A, B, C); //~ ERROR E0425
diff --git a/tests/ui/argument-suggestions/issue-109831.stderr b/tests/ui/argument-suggestions/issue-109831.stderr
index 1a3a597175d83..6c25236ebb1b0 100644
--- a/tests/ui/argument-suggestions/issue-109831.stderr
+++ b/tests/ui/argument-suggestions/issue-109831.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `C` in this scope
+error[E0425]: cannot find type `C` in this scope
   --> $DIR/issue-109831.rs:4:24
    |
 LL | struct A;
@@ -48,5 +48,5 @@ LL +     f(/* B */, /* B */, B);
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0061, E0412, E0425.
+Some errors have detailed explanations: E0061, E0425.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/asm/issue-113788.rs b/tests/ui/asm/issue-113788.rs
index 3b11e253eda27..2c01639824c40 100644
--- a/tests/ui/asm/issue-113788.rs
+++ b/tests/ui/asm/issue-113788.rs
@@ -2,6 +2,6 @@
 //@ needs-asm-support
 //@ only-x86_64
 fn main() {
-    let peb: *const PEB; //~ ERROR cannot find type `PEB` in this scope [E0412]
+    let peb: *const PEB; //~ ERROR cannot find type `PEB` in this scope [E0425]
     unsafe { std::arch::asm!("mov {0}, fs:[0x30]", out(reg) peb); }
 }
diff --git a/tests/ui/asm/issue-113788.stderr b/tests/ui/asm/issue-113788.stderr
index c44ba3c91d91a..ab175e9ee29bb 100644
--- a/tests/ui/asm/issue-113788.stderr
+++ b/tests/ui/asm/issue-113788.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `PEB` in this scope
+error[E0425]: cannot find type `PEB` in this scope
   --> $DIR/issue-113788.rs:5:21
    |
 LL |     let peb: *const PEB;
@@ -6,4 +6,4 @@ LL |     let peb: *const PEB;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/associated-consts/issue-93835.stderr b/tests/ui/associated-consts/issue-93835.stderr
index 551b50d0eb6b5..3f16798901303 100644
--- a/tests/ui/associated-consts/issue-93835.stderr
+++ b/tests/ui/associated-consts/issue-93835.stderr
@@ -4,7 +4,7 @@ error[E0425]: cannot find value `p` in this scope
 LL |     type_ascribe!(p, a<p:p<e=6>>);
    |                   ^ not found in this scope
 
-error[E0412]: cannot find type `a` in this scope
+error[E0425]: cannot find type `a` in this scope
   --> $DIR/issue-93835.rs:4:22
    |
 LL |     type_ascribe!(p, a<p:p<e=6>>);
@@ -39,5 +39,5 @@ LL |     type_ascribe!(p, a<p:p<e=6>>);
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0405, E0412, E0425, E0658.
+Some errors have detailed explanations: E0405, E0425, E0658.
 For more information about an error, try `rustc --explain E0405`.
diff --git a/tests/ui/associated-type-bounds/return-type-notation/not-a-method.stderr b/tests/ui/associated-type-bounds/return-type-notation/not-a-method.stderr
index ab987ee48e6c8..bf5b432e74f1c 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/not-a-method.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/not-a-method.stderr
@@ -16,7 +16,7 @@ error[E0576]: cannot find function `method` in this scope
 LL |     method(..): Send,
    |     ^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `method` in this scope
+error[E0425]: cannot find type `method` in this scope
   --> $DIR/not-a-method.rs:36:5
    |
 LL |     method(): Send,
@@ -36,5 +36,5 @@ LL |     method(..): Send,
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0412, E0573, E0575, E0576.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0573, E0575, E0576.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/associated-types/associated-types-eq-1.stderr b/tests/ui/associated-types/associated-types-eq-1.stderr
index 581ad25d88ac0..869583df644fd 100644
--- a/tests/ui/associated-types/associated-types-eq-1.stderr
+++ b/tests/ui/associated-types/associated-types-eq-1.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-types-eq-1.rs:10:12
    |
 LL | fn foo2<I: Foo>(x: I) {
@@ -18,4 +18,4 @@ LL | fn foo2<I: Foo, A>(x: I) {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/async-await/in-trait/return-not-existing-pair.rs b/tests/ui/async-await/in-trait/return-not-existing-pair.rs
index 3889efe1f2a3c..d4e6e64cfa027 100644
--- a/tests/ui/async-await/in-trait/return-not-existing-pair.rs
+++ b/tests/ui/async-await/in-trait/return-not-existing-pair.rs
@@ -3,7 +3,7 @@
 
 trait MyTrait<'a, 'b, T> {
     async fn foo(&'a self, key: &'b T) -> (&'a ConnImpl, &'b T);
-    //~^ ERROR: cannot find type `ConnImpl` in this scope [E0412]
+    //~^ ERROR: cannot find type `ConnImpl` in this scope [E0425]
 }
 
 impl<'a, 'b, T, U> MyTrait<T> for U {
diff --git a/tests/ui/async-await/in-trait/return-not-existing-pair.stderr b/tests/ui/async-await/in-trait/return-not-existing-pair.stderr
index 13d3606abba78..c92bce7888b30 100644
--- a/tests/ui/async-await/in-trait/return-not-existing-pair.stderr
+++ b/tests/ui/async-await/in-trait/return-not-existing-pair.stderr
@@ -9,7 +9,7 @@ help: indicate the anonymous lifetimes
 LL | impl<'a, 'b, T, U> MyTrait<'_, '_, T> for U {
    |                            +++++++
 
-error[E0412]: cannot find type `ConnImpl` in this scope
+error[E0425]: cannot find type `ConnImpl` in this scope
   --> $DIR/return-not-existing-pair.rs:5:48
    |
 LL |     async fn foo(&'a self, key: &'b T) -> (&'a ConnImpl, &'b T);
@@ -26,5 +26,5 @@ LL |     async fn foo(_: T) -> (&'a U, &'b T) {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0412, E0726.
+Some errors have detailed explanations: E0308, E0425, E0726.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.rs b/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.rs
index e45fca6de770f..337a2c69525ac 100644
--- a/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.rs
+++ b/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.rs
@@ -5,7 +5,7 @@ struct Wrapper<T>(T);
 
 trait Foo {
     fn bar() -> Wrapper<Missing<impl Sized>>;
-    //~^ ERROR: cannot find type `Missing` in this scope [E0412]
+    //~^ ERROR: cannot find type `Missing` in this scope [E0425]
 }
 
 impl Foo for () {
diff --git a/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.stderr b/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.stderr
index 84e0a643485f7..1c88d1c5250b5 100644
--- a/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.stderr
+++ b/tests/ui/async-await/in-trait/return-not-existing-type-wrapping-rpitit.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/return-not-existing-type-wrapping-rpitit.rs:7:25
    |
 LL |     fn bar() -> Wrapper<Missing<impl Sized>>;
@@ -6,4 +6,4 @@ LL |     fn bar() -> Wrapper<Missing<impl Sized>>;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/async-await/issue-72590-type-error-sized.stderr b/tests/ui/async-await/issue-72590-type-error-sized.stderr
index 778423578e169..1d030278fd64e 100644
--- a/tests/ui/async-await/issue-72590-type-error-sized.stderr
+++ b/tests/ui/async-await/issue-72590-type-error-sized.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Nonexistent` in this scope
+error[E0425]: cannot find type `Nonexistent` in this scope
   --> $DIR/issue-72590-type-error-sized.rs:6:10
    |
 LL |     foo: Nonexistent,
    |          ^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/issue-72590-type-error-sized.rs:11:11
    |
 LL |     test: Missing
@@ -30,5 +30,5 @@ LL |     async fn frob(&self) {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/async-await/unconstrained-lifetimes.stderr b/tests/ui/async-await/unconstrained-lifetimes.stderr
index 18a46a3b55518..e979bdfa895e0 100644
--- a/tests/ui/async-await/unconstrained-lifetimes.stderr
+++ b/tests/ui/async-await/unconstrained-lifetimes.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unconstrained-lifetimes.rs:6:17
    |
 LL | async fn foo(_: Missing<'_>) {}
@@ -6,4 +6,4 @@ LL | async fn foo(_: Missing<'_>) {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/attributes/align-on-fields-143987.stderr b/tests/ui/attributes/align-on-fields-143987.stderr
index 2356cdb1e5fb9..c95543a74c1a1 100644
--- a/tests/ui/attributes/align-on-fields-143987.stderr
+++ b/tests/ui/attributes/align-on-fields-143987.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `usize8` in this scope
+error[E0425]: cannot find type `usize8` in this scope
   --> $DIR/align-on-fields-143987.rs:17:8
    |
 LL |     x: usize8,
@@ -30,4 +30,4 @@ LL |     #[rustc_align(32)]
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/borrowck/bad-drop-side-effects.stderr b/tests/ui/borrowck/bad-drop-side-effects.stderr
index 0a5998c7e4830..8ba74f26e44b7 100644
--- a/tests/ui/borrowck/bad-drop-side-effects.stderr
+++ b/tests/ui/borrowck/bad-drop-side-effects.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/bad-drop-side-effects.rs:7:16
    |
 LL | impl<U> B for &Missing {
@@ -6,4 +6,4 @@ LL | impl<U> B for &Missing {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/c-variadic/issue-86053-1.stderr b/tests/ui/c-variadic/issue-86053-1.stderr
index 05b19624129e4..d9bce99cfdb4d 100644
--- a/tests/ui/c-variadic/issue-86053-1.stderr
+++ b/tests/ui/c-variadic/issue-86053-1.stderr
@@ -54,7 +54,7 @@ LL |     self , _: ... ,   self ,   self , _: ... ) where F : FnOnce ( & 'a & 'b
    |
    = help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
 
-error[E0412]: cannot find type `F` in this scope
+error[E0425]: cannot find type `F` in this scope
   --> $DIR/issue-86053-1.rs:11:54
    |
 LL |     self , _: ... ,   self ,   self , _: ... ) where F : FnOnce ( & 'a & 'b usize ) {
@@ -74,4 +74,4 @@ LL | fn ordering4 < 'a , 'b, F     > ( a :            ,   self , self ,   self ,
 
 error: aborting due to 10 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/cast/casts-issue-46365.stderr b/tests/ui/cast/casts-issue-46365.stderr
index 84bc73a9b7862..e1074b36784ef 100644
--- a/tests/ui/cast/casts-issue-46365.stderr
+++ b/tests/ui/cast/casts-issue-46365.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Ipsum` in this scope
+error[E0425]: cannot find type `Ipsum` in this scope
   --> $DIR/casts-issue-46365.rs:2:12
    |
 LL |     ipsum: Ipsum
@@ -6,4 +6,4 @@ LL |     ipsum: Ipsum
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/cast/ice-cast-type-with-error-124848.stderr b/tests/ui/cast/ice-cast-type-with-error-124848.stderr
index 316a484d97154..dff2277273248 100644
--- a/tests/ui/cast/ice-cast-type-with-error-124848.stderr
+++ b/tests/ui/cast/ice-cast-type-with-error-124848.stderr
@@ -31,7 +31,7 @@ help: consider introducing lifetime `'a` here
 LL | fn main<'a>() {
    |        ++++
 
-error[E0412]: cannot find type `Pin` in this scope
+error[E0425]: cannot find type `Pin` in this scope
   --> $DIR/ice-cast-type-with-error-124848.rs:7:60
    |
 LL | struct MyType<'a>(Cell<Option<&'unpinned mut MyType<'a>>>, Pin);
@@ -66,5 +66,5 @@ LL |     let bad_addr = &unpinned as *const Cell<Option<&'a mut MyType<'a>>> as
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0061, E0261, E0412, E0606.
+Some errors have detailed explanations: E0061, E0261, E0425, E0606.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/closures/issue-78720.stderr b/tests/ui/closures/issue-78720.stderr
index 987625d22c9d3..8c6eca05afcdd 100644
--- a/tests/ui/closures/issue-78720.stderr
+++ b/tests/ui/closures/issue-78720.stderr
@@ -4,7 +4,7 @@ error: at least one trait must be specified
 LL | fn server() -> impl {
    |                ^^^^
 
-error[E0412]: cannot find type `F` in this scope
+error[E0425]: cannot find type `F` in this scope
   --> $DIR/issue-78720.rs:14:12
    |
 LL |     _func: F,
@@ -55,5 +55,5 @@ LL |     fn map2<F>(&self, f: F) -> Map2<F> {}
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0277, E0282, E0308, E0412.
+Some errors have detailed explanations: E0277, E0282, E0308, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/closures/issue-90871.stderr b/tests/ui/closures/issue-90871.stderr
index 12020226680b2..071694def4135 100644
--- a/tests/ui/closures/issue-90871.stderr
+++ b/tests/ui/closures/issue-90871.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `n` in this scope
+error[E0425]: cannot find type `n` in this scope
   --> $DIR/issue-90871.rs:4:22
    |
 LL |     type_ascribe!(2, n([u8; || 1]))
@@ -23,5 +23,5 @@ LL |     type_ascribe!(2, n([u8; (|| 1)()]))
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0308, E0412.
+Some errors have detailed explanations: E0308, E0425.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/generics.stderr b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/generics.stderr
index 75da78b0b75a9..a3848182ef14b 100644
--- a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/generics.stderr
+++ b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/generics.stderr
@@ -4,7 +4,7 @@ error: function pointer types may not have generic parameters
 LL |     f1: extern "cmse-nonsecure-call" fn<U: Copy>(U, u32, u32, u32) -> u64,
    |                                        ^^^^^^^^^
 
-error[E0412]: cannot find type `U` in this scope
+error[E0425]: cannot find type `U` in this scope
   --> $DIR/generics.rs:14:50
    |
 LL | struct Test<T: Copy> {
@@ -101,5 +101,5 @@ LL | type WithVarArgs = extern "cmse-nonsecure-call" fn(u32, ...);
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0045, E0412, E0562, E0798.
+Some errors have detailed explanations: E0045, E0425, E0562, E0798.
 For more information about an error, try `rustc --explain E0045`.
diff --git a/tests/ui/coercion/type-errors.stderr b/tests/ui/coercion/type-errors.stderr
index 14deb785f75aa..3d2aab3bbd96f 100644
--- a/tests/ui/coercion/type-errors.stderr
+++ b/tests/ui/coercion/type-errors.stderr
@@ -1,16 +1,16 @@
-error[E0412]: cannot find type `TypeError` in this scope
+error[E0425]: cannot find type `TypeError` in this scope
   --> $DIR/type-errors.rs:5:23
    |
 LL | pub fn has_error() -> TypeError {}
    |                       ^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `TypeError` in this scope
+error[E0425]: cannot find type `TypeError` in this scope
   --> $DIR/type-errors.rs:18:29
    |
 LL | pub fn autoderef_source(e: &TypeError) {
    |                             ^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `TypeError` in this scope
+error[E0425]: cannot find type `TypeError` in this scope
   --> $DIR/type-errors.rs:23:29
    |
 LL | pub fn autoderef_target(_: &TypeError) {}
@@ -18,4 +18,4 @@ LL | pub fn autoderef_target(_: &TypeError) {}
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/coherence/coherence-error-suppression.rs b/tests/ui/coherence/coherence-error-suppression.rs
index 909214c1b6e37..cf66e91d7ba34 100644
--- a/tests/ui/coherence/coherence-error-suppression.rs
+++ b/tests/ui/coherence/coherence-error-suppression.rs
@@ -7,7 +7,7 @@ impl Foo for i16 {}
 impl Foo for i32 {}
 impl Foo for i64 {}
 impl Foo for DoesNotExist {}
-//~^ ERROR E0412
+//~^ ERROR E0425
 impl Foo for u8 {}
 impl Foo for u16 {}
 impl Foo for u32 {}
diff --git a/tests/ui/coherence/coherence-error-suppression.stderr b/tests/ui/coherence/coherence-error-suppression.stderr
index fcaa510c632a8..61d3e086dada3 100644
--- a/tests/ui/coherence/coherence-error-suppression.stderr
+++ b/tests/ui/coherence/coherence-error-suppression.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `DoesNotExist` in this scope
+error[E0425]: cannot find type `DoesNotExist` in this scope
   --> $DIR/coherence-error-suppression.rs:9:14
    |
 LL | impl Foo for DoesNotExist {}
@@ -6,4 +6,4 @@ LL | impl Foo for DoesNotExist {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/coherence/illegal-copy-bad-projection.stderr b/tests/ui/coherence/illegal-copy-bad-projection.stderr
index 2a74cb5a9b8b1..e85ac6069155d 100644
--- a/tests/ui/coherence/illegal-copy-bad-projection.stderr
+++ b/tests/ui/coherence/illegal-copy-bad-projection.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `void` in this scope
+error[E0425]: cannot find type `void` in this scope
   --> $DIR/illegal-copy-bad-projection.rs:6:23
    |
 LL |     type Ptr = *const void;
@@ -6,4 +6,4 @@ LL |     type Ptr = *const void;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/coherence/impl-coherence-error-for-undefined-type-18058.stderr b/tests/ui/coherence/impl-coherence-error-for-undefined-type-18058.stderr
index 07dce0b04fd53..4883b35196200 100644
--- a/tests/ui/coherence/impl-coherence-error-for-undefined-type-18058.stderr
+++ b/tests/ui/coherence/impl-coherence-error-for-undefined-type-18058.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Undefined` in this scope
+error[E0425]: cannot find type `Undefined` in this scope
   --> $DIR/impl-coherence-error-for-undefined-type-18058.rs:2:6
    |
 LL | impl Undefined {}
@@ -6,4 +6,4 @@ LL | impl Undefined {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/compiletest-self-test/ui-testing-optout.stderr b/tests/ui/compiletest-self-test/ui-testing-optout.stderr
index f1d03eab14a9d..b0d495edfb62a 100644
--- a/tests/ui/compiletest-self-test/ui-testing-optout.stderr
+++ b/tests/ui/compiletest-self-test/ui-testing-optout.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `B` in this scope
+error[E0425]: cannot find type `B` in this scope
  --> $DIR/ui-testing-optout.rs:4:10
   |
 4 | type A = B;
   |          ^ not found in this scope
 
-error[E0412]: cannot find type `D` in this scope
+error[E0425]: cannot find type `D` in this scope
  --> $DIR/ui-testing-optout.rs:7:10
   |
 4 | type A = B;
@@ -13,7 +13,7 @@ error[E0412]: cannot find type `D` in this scope
 7 | type C = D;
   |          ^ help: a type alias with a similar name exists: `A`
 
-error[E0412]: cannot find type `F` in this scope
+error[E0425]: cannot find type `F` in this scope
   --> $DIR/ui-testing-optout.rs:92:10
    |
  4 | type A = B;
@@ -24,4 +24,4 @@ error[E0412]: cannot find type `F` in this scope
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr
index 58d42d82998bf..26d80c85e1610 100644
--- a/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr
+++ b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr
@@ -9,7 +9,7 @@ LL | | >;
    | |__|
    |
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/const_arg_trivial_macro_expansion-2.rs:12:10
    |
 LL | const _: A<
@@ -32,5 +32,4 @@ LL | const _<const x: /* Type */>: A<
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/early/invalid-const-arguments.stderr b/tests/ui/const-generics/early/invalid-const-arguments.stderr
index 3a9868836ec88..a0a6d8cc8679b 100644
--- a/tests/ui/const-generics/early/invalid-const-arguments.stderr
+++ b/tests/ui/const-generics/early/invalid-const-arguments.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/invalid-const-arguments.rs:5:16
    |
 LL | struct A<const N: u8>;
@@ -17,7 +17,7 @@ help: you might be missing a type parameter
 LL | impl<N> Foo for A<N> {}
    |     +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/invalid-const-arguments.rs:14:32
    |
 LL | struct A<const N: u8>;
@@ -72,5 +72,5 @@ LL | impl<const N: u8> Foo for C<N, { T }> {}
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0412, E0747.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0747.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.stderr b/tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.stderr
index c9c8115660f27..733a7f4f197d5 100644
--- a/tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `F` in this scope
+error[E0425]: cannot find type `F` in this scope
   --> $DIR/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs:11:17
    |
 LL |          let f: F = async { 1 };
@@ -59,5 +59,5 @@ LL | ) -> impl Iterator<Item = SubAssign> {
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0277, E0412, E0782.
+Some errors have detailed explanations: E0277, E0425, E0782.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/generic_const_exprs/ice-predicates-of-no-entry-found-for-key-119275.stderr b/tests/ui/const-generics/generic_const_exprs/ice-predicates-of-no-entry-found-for-key-119275.stderr
index 6037e685e44d7..8e9b5b03d14ee 100644
--- a/tests/ui/const-generics/generic_const_exprs/ice-predicates-of-no-entry-found-for-key-119275.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/ice-predicates-of-no-entry-found-for-key-119275.stderr
@@ -15,7 +15,7 @@ LL | fn bug<const N: Nat>(&self)
 LL |     for<const N: usize = 3, T = u32> [(); COT::BYTES]:,
    |               ^ already used
 
-error[E0412]: cannot find type `Nat` in this scope
+error[E0425]: cannot find type `Nat` in this scope
   --> $DIR/ice-predicates-of-no-entry-found-for-key-119275.rs:6:17
    |
 LL | fn bug<const N: Nat>(&self)
@@ -51,5 +51,5 @@ LL |     for<const N: usize = 3, T = u32> [(); COT::BYTES]:,
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0403, E0412, E0433, E0658.
+Some errors have detailed explanations: E0403, E0425, E0433, E0658.
 For more information about an error, try `rustc --explain E0403`.
diff --git a/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr b/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr
index 453079e3c1575..d3a7e286fdd60 100644
--- a/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr
@@ -13,7 +13,7 @@ error[E0425]: cannot find value `v8` in this scope
 LL |     const v0: [[usize; v4]; v4] = v6(v8);
    |                                      ^^ not found in this scope
 
-error[E0412]: cannot find type `v18` in this scope
+error[E0425]: cannot find type `v18` in this scope
   --> $DIR/unevaluated-const-ice-119731.rs:23:31
    |
 LL |     pub type v11 = [[usize; v4]; v4];
@@ -22,7 +22,7 @@ LL |     pub type v11 = [[usize; v4]; v4];
 LL |         pub const fn v21() -> v18 {}
    |                               ^^^ help: a type alias with a similar name exists: `v11`
 
-error[E0412]: cannot find type `v18` in this scope
+error[E0425]: cannot find type `v18` in this scope
   --> $DIR/unevaluated-const-ice-119731.rs:35:31
    |
 LL |     pub type v11 = [[usize; v4]; v4];
@@ -129,5 +129,5 @@ LL |         pub const fn v21() -> v18 {
 
 error: aborting due to 14 previous errors; 2 warnings emitted
 
-Some errors have detailed explanations: E0412, E0422, E0425, E0432, E0592.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0422, E0425, E0432, E0592.
+For more information about an error, try `rustc --explain E0422`.
diff --git a/tests/ui/const-generics/mgca/projection-error.stderr b/tests/ui/const-generics/mgca/projection-error.stderr
index e60acf9144b5c..9357600a5e113 100644
--- a/tests/ui/const-generics/mgca/projection-error.stderr
+++ b/tests/ui/const-generics/mgca/projection-error.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/projection-error.rs:14:17
    |
 LL | pub trait Tr<A> {
@@ -16,7 +16,7 @@ help: you might be missing a type parameter
 LL | fn mk_array<T>(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
    |            +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/projection-error.rs:14:29
    |
 LL | pub trait Tr<A> {
@@ -36,4 +36,4 @@ LL | fn mk_array<T>(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/parent_generics_of_nested_in_default.stderr b/tests/ui/const-generics/parent_generics_of_nested_in_default.stderr
index 24e05482a1a99..00eeecb9595f3 100644
--- a/tests/ui/const-generics/parent_generics_of_nested_in_default.stderr
+++ b/tests/ui/const-generics/parent_generics_of_nested_in_default.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Tr` in this scope
+error[E0425]: cannot find type `Tr` in this scope
   --> $DIR/parent_generics_of_nested_in_default.rs:1:36
    |
 LL | impl<const A: i32 = { || [0; B] }> Tr {}
@@ -20,5 +20,4 @@ LL | impl<const A: i32 = { || [0; B] }> Tr {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/trait-resolution-error-with-const-generics-77919.stderr b/tests/ui/const-generics/trait-resolution-error-with-const-generics-77919.stderr
index bac8abf46dce9..2aa79df096579 100644
--- a/tests/ui/const-generics/trait-resolution-error-with-const-generics-77919.stderr
+++ b/tests/ui/const-generics/trait-resolution-error-with-const-generics-77919.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `PhantomData` in this scope
+error[E0425]: cannot find type `PhantomData` in this scope
   --> $DIR/trait-resolution-error-with-const-generics-77919.rs:10:9
    |
 LL |     _n: PhantomData,
@@ -9,7 +9,7 @@ help: consider importing this struct
 LL + use std::marker::PhantomData;
    |
 
-error[E0412]: cannot find type `VAL` in this scope
+error[E0425]: cannot find type `VAL` in this scope
   --> $DIR/trait-resolution-error-with-const-generics-77919.rs:12:63
    |
 LL | impl<N, M> TypeVal<usize> for Multiply<N, M> where N: TypeVal<VAL> {}
@@ -31,5 +31,5 @@ LL | impl<N, M> TypeVal<usize> for Multiply<N, M> where N: TypeVal<VAL> {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0046, E0412.
+Some errors have detailed explanations: E0046, E0425.
 For more information about an error, try `rustc --explain E0046`.
diff --git a/tests/ui/const-generics/type_not_in_scope.stderr b/tests/ui/const-generics/type_not_in_scope.stderr
index 5f45550a62796..f676108d37d0d 100644
--- a/tests/ui/const-generics/type_not_in_scope.stderr
+++ b/tests/ui/const-generics/type_not_in_scope.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `X` in this scope
+error[E0425]: cannot find type `X` in this scope
   --> $DIR/type_not_in_scope.rs:1:6
    |
 LL | impl X {
@@ -20,5 +20,5 @@ LL | fn getn<const N: cfg_attr>() -> [u8; N] {}
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0412, E0573.
+Some errors have detailed explanations: E0308, E0425, E0573.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/unknown_adt.stderr b/tests/ui/const-generics/unknown_adt.stderr
index 2e8210772e94a..b905299daf622 100644
--- a/tests/ui/const-generics/unknown_adt.stderr
+++ b/tests/ui/const-generics/unknown_adt.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `UnknownStruct` in this scope
+error[E0425]: cannot find type `UnknownStruct` in this scope
   --> $DIR/unknown_adt.rs:2:12
    |
 LL |     let _: UnknownStruct<7>;
@@ -6,4 +6,4 @@ LL |     let _: UnknownStruct<7>;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/const_prop/ice-type-mismatch-when-copying-112824.stderr b/tests/ui/const_prop/ice-type-mismatch-when-copying-112824.stderr
index 586c96011e438..3da0f17dcf80a 100644
--- a/tests/ui/const_prop/ice-type-mismatch-when-copying-112824.stderr
+++ b/tests/ui/const_prop/ice-type-mismatch-when-copying-112824.stderr
@@ -9,7 +9,7 @@ help: consider introducing lifetime `'a` here
 LL | pub struct Opcode2<'a>(&'a S);
    |                   ++++
 
-error[E0412]: cannot find type `S` in this scope
+error[E0425]: cannot find type `S` in this scope
   --> $DIR/ice-type-mismatch-when-copying-112824.rs:5:24
    |
 LL | pub struct Opcode2(&'a S);
@@ -22,5 +22,5 @@ LL | pub struct Opcode2<S>(&'a S);
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0261, E0412.
+Some errors have detailed explanations: E0261, E0425.
 For more information about an error, try `rustc --explain E0261`.
diff --git a/tests/ui/consts/erroneous_type_in_const_return_value.stderr b/tests/ui/consts/erroneous_type_in_const_return_value.stderr
index 453f5b640973f..9f743fa48efc7 100644
--- a/tests/ui/consts/erroneous_type_in_const_return_value.stderr
+++ b/tests/ui/consts/erroneous_type_in_const_return_value.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Sum` in this scope
+error[E0425]: cannot find type `Sum` in this scope
   --> $DIR/erroneous_type_in_const_return_value.rs:6:22
    |
 LL |     UnusedByTheConst(Sum),
@@ -11,4 +11,4 @@ LL + use std::iter::Sum;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/consts/erroneous_type_in_promoted.stderr b/tests/ui/consts/erroneous_type_in_promoted.stderr
index 0601fc9ebe7fb..ce8d58482fc28 100644
--- a/tests/ui/consts/erroneous_type_in_promoted.stderr
+++ b/tests/ui/consts/erroneous_type_in_promoted.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Sum` in this scope
+error[E0425]: cannot find type `Sum` in this scope
   --> $DIR/erroneous_type_in_promoted.rs:6:22
    |
 LL |     UnusedByTheConst(Sum),
@@ -11,4 +11,4 @@ LL + use std::iter::Sum;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/consts/error-is-freeze.stderr b/tests/ui/consts/error-is-freeze.stderr
index f3bfd1ea5e293..51f6b0efec331 100644
--- a/tests/ui/consts/error-is-freeze.stderr
+++ b/tests/ui/consts/error-is-freeze.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `UndefinedType` in this scope
+error[E0425]: cannot find type `UndefinedType` in this scope
   --> $DIR/error-is-freeze.rs:4:17
    |
 LL |     foo: Option<UndefinedType>,
@@ -11,4 +11,4 @@ LL | struct MyStruct<UndefinedType> {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/consts/ice-bad-input-type-for-cast-83056.stderr b/tests/ui/consts/ice-bad-input-type-for-cast-83056.stderr
index 4fc5972051c23..9eb19a0eaca76 100644
--- a/tests/ui/consts/ice-bad-input-type-for-cast-83056.stderr
+++ b/tests/ui/consts/ice-bad-input-type-for-cast-83056.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/ice-bad-input-type-for-cast-83056.rs:5:11
    |
 LL | struct S([bool; f as usize]);
@@ -18,4 +18,4 @@ LL | fn f<T>() -> T {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/did_you_mean/issue-56028-there-is-an-enum-variant.stderr b/tests/ui/did_you_mean/issue-56028-there-is-an-enum-variant.stderr
index 887fcf0b73c43..98b80383c3dc1 100644
--- a/tests/ui/did_you_mean/issue-56028-there-is-an-enum-variant.stderr
+++ b/tests/ui/did_you_mean/issue-56028-there-is-an-enum-variant.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Set` in this scope
+error[E0425]: cannot find type `Set` in this scope
   --> $DIR/issue-56028-there-is-an-enum-variant.rs:10:15
    |
 LL | fn setup() -> Set { Set }
@@ -40,5 +40,4 @@ LL + use PutDown::Set;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/did_you_mean/sugg-stable-import-first-issue-140240.stderr b/tests/ui/did_you_mean/sugg-stable-import-first-issue-140240.stderr
index ca8f8cc07afbf..2e268082cefb8 100644
--- a/tests/ui/did_you_mean/sugg-stable-import-first-issue-140240.stderr
+++ b/tests/ui/did_you_mean/sugg-stable-import-first-issue-140240.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Range` in this scope
+error[E0425]: cannot find type `Range` in this scope
   --> $DIR/sugg-stable-import-first-issue-140240.rs:3:14
    |
 LL |     const _: Range = 0..1;
@@ -17,4 +17,4 @@ LL + use std::range::Range;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/dropck/drop-on-non-struct.stderr b/tests/ui/dropck/drop-on-non-struct.stderr
index 9495642e45e4d..6a23c4c174aa4 100644
--- a/tests/ui/dropck/drop-on-non-struct.stderr
+++ b/tests/ui/dropck/drop-on-non-struct.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Nonexistent` in this scope
+error[E0425]: cannot find type `Nonexistent` in this scope
   --> $DIR/drop-on-non-struct.rs:9:15
    |
 LL | impl Drop for Nonexistent {
@@ -24,5 +24,5 @@ LL | impl<'a> Drop for &'a mut isize {
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0117, E0120, E0412.
+Some errors have detailed explanations: E0117, E0120, E0425.
 For more information about an error, try `rustc --explain E0117`.
diff --git a/tests/ui/dyn-compatibility/erroneous_signature.stderr b/tests/ui/dyn-compatibility/erroneous_signature.stderr
index f3b14ffe34c3b..8077f224f064f 100644
--- a/tests/ui/dyn-compatibility/erroneous_signature.stderr
+++ b/tests/ui/dyn-compatibility/erroneous_signature.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/erroneous_signature.rs:2:22
    |
 LL |     fn err(&self) -> MissingType;
    |                      ^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/erroneous_signature.rs:7:22
    |
 LL |     fn err(&self) -> MissingType {
@@ -12,4 +12,4 @@ LL |     fn err(&self) -> MissingType {
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/enum-discriminant/ice-from-type-error-issue-148515.stderr b/tests/ui/enum-discriminant/ice-from-type-error-issue-148515.stderr
index d9f40c7c0f738..37a972a6a8309 100644
--- a/tests/ui/enum-discriminant/ice-from-type-error-issue-148515.stderr
+++ b/tests/ui/enum-discriminant/ice-from-type-error-issue-148515.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/ice-from-type-error-issue-148515.rs:7:34
    |
 LL | fn test1(x: impl Iterator<Item = Foo>) {
    |                                  ^^^ not found in this scope
 
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/ice-from-type-error-issue-148515.rs:12:34
    |
 LL | fn test2(_: impl Iterator<Item = Foo>) {
@@ -20,5 +20,5 @@ LL |     0u8 == -3;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0600.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0600.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/error-codes/E0412.rs b/tests/ui/error-codes/E0412.rs
index 5f922a50a68ed..2c69c5e6b5cfc 100644
--- a/tests/ui/error-codes/E0412.rs
+++ b/tests/ui/error-codes/E0412.rs
@@ -1,4 +1,4 @@
-impl Something {} //~ ERROR E0412
+impl Something {} //~ ERROR E0425
 
 fn main() {
 }
diff --git a/tests/ui/error-codes/E0412.stderr b/tests/ui/error-codes/E0412.stderr
index 7c1172642faff..4a4abf009c841 100644
--- a/tests/ui/error-codes/E0412.stderr
+++ b/tests/ui/error-codes/E0412.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Something` in this scope
+error[E0425]: cannot find type `Something` in this scope
   --> $DIR/E0412.rs:1:6
    |
 LL | impl Something {}
@@ -6,4 +6,4 @@ LL | impl Something {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/extern/issue-112363-extern-item-where-clauses-debug-ice.stderr b/tests/ui/extern/issue-112363-extern-item-where-clauses-debug-ice.stderr
index 039e50b5e12da..b63cc29e56066 100644
--- a/tests/ui/extern/issue-112363-extern-item-where-clauses-debug-ice.stderr
+++ b/tests/ui/extern/issue-112363-extern-item-where-clauses-debug-ice.stderr
@@ -20,13 +20,13 @@ LL |     type Item = [T] where [T]: Sized;
    |
    = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/issue-112363-extern-item-where-clauses-debug-ice.rs:2:28
    |
 LL |     type Item = [T] where [T]: Sized;
    |                            ^ not found in this scope
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/issue-112363-extern-item-where-clauses-debug-ice.rs:2:18
    |
 LL |     type Item = [T] where [T]: Sized;
@@ -44,5 +44,5 @@ LL |     type Item = [T] where [T]: Sized;
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0412, E0658.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0658.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/fn/trait-fn-generic-mismatch.stderr b/tests/ui/fn/trait-fn-generic-mismatch.stderr
index 8384d74e225aa..470865ae3a685 100644
--- a/tests/ui/fn/trait-fn-generic-mismatch.stderr
+++ b/tests/ui/fn/trait-fn-generic-mismatch.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `XXX` in this scope
+error[E0425]: cannot find type `XXX` in this scope
   --> $DIR/trait-fn-generic-mismatch.rs:5:11
    |
 LL | impl Core<XXX> {
@@ -28,5 +28,5 @@ LL +     core.spawn();
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0061, E0412.
+Some errors have detailed explanations: E0061, E0425.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/functions-closures/fn-help-with-err-generic-is-not-function.stderr b/tests/ui/functions-closures/fn-help-with-err-generic-is-not-function.stderr
index 9d4ea01152cc9..af425cc6ed823 100644
--- a/tests/ui/functions-closures/fn-help-with-err-generic-is-not-function.stderr
+++ b/tests/ui/functions-closures/fn-help-with-err-generic-is-not-function.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/fn-help-with-err-generic-is-not-function.rs:2:13
    |
 LL | impl Struct<T>
@@ -9,7 +9,7 @@ help: you might be missing a type parameter
 LL | impl<T> Struct<T>
    |     +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/fn-help-with-err-generic-is-not-function.rs:7:5
    |
 LL |     T: Copy,
@@ -17,4 +17,4 @@ LL |     T: Copy,
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/generic-associated-types/equality-bound.stderr b/tests/ui/generic-associated-types/equality-bound.stderr
index a054c06caebde..03fafe3e21c1d 100644
--- a/tests/ui/generic-associated-types/equality-bound.stderr
+++ b/tests/ui/generic-associated-types/equality-bound.stderr
@@ -110,7 +110,7 @@ LL -     fn from_iter<T>(_: T) -> Self where T::Item = A, T: IntoIterator,
 LL +     fn from_iter<T>(_: T) -> Self where T: IntoIterator<Item = A>,
    |
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:20:79
    |
 LL |     fn from_iter<T>(_: T) -> Self where T: IntoIterator, IntoIterator::Item = A,
@@ -119,7 +119,7 @@ LL |     fn from_iter<T>(_: T) -> Self where T: IntoIterator, IntoIterator::Item
 LL | struct K {}
    | -------- similarly named struct `K` defined here
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:31:68
    |
 LL |     fn from_iter<T>(_: T) -> Self where T: IntoIterator, T::Item = A,
@@ -128,7 +128,7 @@ LL |     fn from_iter<T>(_: T) -> Self where T: IntoIterator, T::Item = A,
 LL | struct K {}
    | -------- similarly named struct `K` defined here
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:42:76
    |
 LL |     fn from_iter<T: IntoIterator>(_: T) -> Self where IntoIterator::Item = A,
@@ -137,7 +137,7 @@ LL |     fn from_iter<T: IntoIterator>(_: T) -> Self where IntoIterator::Item =
 LL | struct K {}
    | -------- similarly named struct `K` defined here
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:53:65
    |
 LL | struct K {}
@@ -146,7 +146,7 @@ LL | struct K {}
 LL |     fn from_iter<T: IntoIterator>(_: T) -> Self where T::Item = A,
    |                                                                 ^ help: a struct with a similar name exists: `K`
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:64:62
    |
 LL | struct K {}
@@ -155,7 +155,7 @@ LL | struct K {}
 LL |     fn from_iter<T>(_: T) -> Self where IntoIterator::Item = A, T: IntoIterator,
    |                                                              ^ help: a struct with a similar name exists: `K`
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/equality-bound.rs:75:51
    |
 LL | struct K {}
@@ -175,5 +175,5 @@ LL | fn sum3<J: Iterator>(i: J) -> i32 where I::Item = i32 {
 
 error: aborting due to 16 previous errors
 
-Some errors have detailed explanations: E0412, E0433.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0433.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/hygiene/arguments.stderr b/tests/ui/hygiene/arguments.stderr
index fe92daf643796..eff6ecd47a5bf 100644
--- a/tests/ui/hygiene/arguments.stderr
+++ b/tests/ui/hygiene/arguments.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `S` in this scope
+error[E0425]: cannot find type `S` in this scope
   --> $DIR/arguments.rs:14:8
    |
 LL |         struct S;
@@ -9,4 +9,4 @@ LL |     m!(S, S);
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/hygiene/generate-mod.stderr b/tests/ui/hygiene/generate-mod.stderr
index 58b9c642dabe3..bfdb72c22cb9b 100644
--- a/tests/ui/hygiene/generate-mod.stderr
+++ b/tests/ui/hygiene/generate-mod.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `FromOutside` in this scope
+error[E0425]: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:35:13
    |
 LL |     type A = $FromOutside;
@@ -7,7 +7,7 @@ LL |     type A = $FromOutside;
 LL |     genmod!(FromOutside, Outer);
    |             ^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Outer` in this scope
+error[E0425]: cannot find type `Outer` in this scope
   --> $DIR/generate-mod.rs:35:26
    |
 LL |     struct $Outer;
@@ -16,7 +16,7 @@ LL |     struct $Outer;
 LL |     genmod!(FromOutside, Outer);
    |                          ^^^^^ not found in this scope
 
-error[E0412]: cannot find type `FromOutside` in this scope
+error[E0425]: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:19:18
    |
 LL |         type A = FromOutside;
@@ -27,7 +27,7 @@ LL |     genmod_transparent!();
    |
    = note: this error originates in the macro `genmod_transparent` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `Outer` in this scope
+error[E0425]: cannot find type `Outer` in this scope
   --> $DIR/generate-mod.rs:20:22
    |
 LL |         type Inner = Outer;
@@ -38,7 +38,7 @@ LL |     genmod_transparent!();
    |
    = note: this error originates in the macro `genmod_transparent` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `FromOutside` in this scope
+error[E0425]: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:28:18
    |
 LL |         type A = FromOutside;
@@ -49,7 +49,7 @@ LL |     genmod_legacy!();
    |
    = note: this error originates in the macro `genmod_legacy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `Outer` in this scope
+error[E0425]: cannot find type `Outer` in this scope
   --> $DIR/generate-mod.rs:29:22
    |
 LL |         type Inner = Outer;
@@ -62,4 +62,4 @@ LL |     genmod_legacy!();
 
 error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/impl-trait/in-trait/ensure-rpitits-are-created-before-freezing.stderr b/tests/ui/impl-trait/in-trait/ensure-rpitits-are-created-before-freezing.stderr
index c172787e6ef21..7245760058770 100644
--- a/tests/ui/impl-trait/in-trait/ensure-rpitits-are-created-before-freezing.stderr
+++ b/tests/ui/impl-trait/in-trait/ensure-rpitits-are-created-before-freezing.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/ensure-rpitits-are-created-before-freezing.rs:8:19
    |
 LL | impl Iterable for Missing {
@@ -6,4 +6,4 @@ LL | impl Iterable for Missing {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/impl-trait/in-trait/refine-err.stderr b/tests/ui/impl-trait/in-trait/refine-err.stderr
index 6b4ef74d50afc..d667b1209dd03 100644
--- a/tests/ui/impl-trait/in-trait/refine-err.stderr
+++ b/tests/ui/impl-trait/in-trait/refine-err.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/refine-err.rs:4:38
    |
 LL |     fn prepare(self) -> impl Fn() -> T;
@@ -6,4 +6,4 @@ LL |     fn prepare(self) -> impl Fn() -> T;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.stderr b/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.stderr
index e7d38f2240642..dd0de45bbf53f 100644
--- a/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.stderr
+++ b/tests/ui/impl-trait/in-trait/rpitit-shadowed-by-missing-adt.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/rpitit-shadowed-by-missing-adt.rs:6:35
    |
 LL |     fn w() -> impl Deref<Target = Missing<impl Sized>>;
@@ -6,4 +6,4 @@ LL |     fn w() -> impl Deref<Target = Missing<impl Sized>>;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/impl-trait/issues/issue-54966.stderr b/tests/ui/impl-trait/issues/issue-54966.stderr
index 4024c5afa80b6..fe20bf42ffc19 100644
--- a/tests/ui/impl-trait/issues/issue-54966.stderr
+++ b/tests/ui/impl-trait/issues/issue-54966.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Oper` in this scope
+error[E0425]: cannot find type `Oper` in this scope
   --> $DIR/issue-54966.rs:3:27
    |
 LL | fn generate_duration() -> Oper<impl FnMut()> {}
@@ -6,4 +6,4 @@ LL | fn generate_duration() -> Oper<impl FnMut()> {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/impl-trait/opaque-used-in-extraneous-argument.stderr b/tests/ui/impl-trait/opaque-used-in-extraneous-argument.stderr
index 73e7890f91fd1..ffa58f4faeeee 100644
--- a/tests/ui/impl-trait/opaque-used-in-extraneous-argument.stderr
+++ b/tests/ui/impl-trait/opaque-used-in-extraneous-argument.stderr
@@ -11,7 +11,7 @@ LL - fn frob() -> impl Fn<P, Output = T> + '_ {}
 LL + fn frob() -> impl Fn<P, Output = T> + 'static {}
    |
 
-error[E0412]: cannot find type `P` in this scope
+error[E0425]: cannot find type `P` in this scope
   --> $DIR/opaque-used-in-extraneous-argument.rs:5:22
    |
 LL | fn frob() -> impl Fn<P, Output = T> + '_ {}
@@ -22,7 +22,7 @@ help: you might be missing a type parameter
 LL | fn frob<P>() -> impl Fn<P, Output = T> + '_ {}
    |        +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/opaque-used-in-extraneous-argument.rs:5:34
    |
 LL | fn frob() -> impl Fn<P, Output = T> + '_ {}
@@ -90,5 +90,5 @@ LL +     open_parent()
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0061, E0106, E0412, E0658.
+Some errors have detailed explanations: E0061, E0106, E0425, E0658.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/implied-bounds/references-err.stderr b/tests/ui/implied-bounds/references-err.stderr
index df83fce3bdef7..9ecda02b1d519 100644
--- a/tests/ui/implied-bounds/references-err.stderr
+++ b/tests/ui/implied-bounds/references-err.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `DoesNotExist` in this scope
+error[E0425]: cannot find type `DoesNotExist` in this scope
   --> $DIR/references-err.rs:14:18
    |
 LL |     type Assoc = DoesNotExist;
@@ -6,4 +6,4 @@ LL |     type Assoc = DoesNotExist;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/glob-conflict-cross-crate-2.stderr b/tests/ui/imports/glob-conflict-cross-crate-2.stderr
index aebb2d59d063a..41912ed63f429 100644
--- a/tests/ui/imports/glob-conflict-cross-crate-2.stderr
+++ b/tests/ui/imports/glob-conflict-cross-crate-2.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `C` in this scope
+error[E0425]: cannot find type `C` in this scope
   --> $DIR/glob-conflict-cross-crate-2.rs:8:13
    |
 LL |     let _a: C = 1;
@@ -6,4 +6,4 @@ LL |     let _a: C = 1;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/glob-resolve1.stderr b/tests/ui/imports/glob-resolve1.stderr
index 30dddba9e9180..1356255a08501 100644
--- a/tests/ui/imports/glob-resolve1.stderr
+++ b/tests/ui/imports/glob-resolve1.stderr
@@ -68,7 +68,7 @@ help: consider importing this function
 LL + use other::import;
    |
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/glob-resolve1.rs:33:11
    |
 LL |     pub enum B {
@@ -83,7 +83,7 @@ note: enum `bar::A` exists but is inaccessible
 LL |     enum A {
    |     ^^^^^^ not accessible
 
-error[E0412]: cannot find type `C` in this scope
+error[E0425]: cannot find type `C` in this scope
   --> $DIR/glob-resolve1.rs:34:11
    |
 LL |     pub enum B {
@@ -98,7 +98,7 @@ note: struct `bar::C` exists but is inaccessible
 LL |     struct C;
    |     ^^^^^^^^^ not accessible
 
-error[E0412]: cannot find type `D` in this scope
+error[E0425]: cannot find type `D` in this scope
   --> $DIR/glob-resolve1.rs:35:11
    |
 LL |     pub enum B {
@@ -115,5 +115,5 @@ LL |     type D = isize;
 
 error: aborting due to 8 previous errors
 
-Some errors have detailed explanations: E0412, E0423, E0425.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0423, E0425.
+For more information about an error, try `rustc --explain E0423`.
diff --git a/tests/ui/imports/import-alias-issue-121168.edition2015.stderr b/tests/ui/imports/import-alias-issue-121168.edition2015.stderr
index 47001fc1a5291..8dee8e5134448 100644
--- a/tests/ui/imports/import-alias-issue-121168.edition2015.stderr
+++ b/tests/ui/imports/import-alias-issue-121168.edition2015.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/import-alias-issue-121168.rs:11:12
    |
 LL |     let _: Foo<i32> = todo!();
@@ -11,4 +11,4 @@ LL + use nice_crate_name::Foo;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/import-alias-issue-121168.edition2018.stderr b/tests/ui/imports/import-alias-issue-121168.edition2018.stderr
index e14e700c33d81..00b30b4c618f0 100644
--- a/tests/ui/imports/import-alias-issue-121168.edition2018.stderr
+++ b/tests/ui/imports/import-alias-issue-121168.edition2018.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/import-alias-issue-121168.rs:11:12
    |
 LL |     let _: Foo<i32> = todo!();
@@ -13,4 +13,4 @@ LL + use import_alias_issue_121168_extern::Foo;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/import-alias-issue-121168.edition2021.stderr b/tests/ui/imports/import-alias-issue-121168.edition2021.stderr
index e14e700c33d81..00b30b4c618f0 100644
--- a/tests/ui/imports/import-alias-issue-121168.edition2021.stderr
+++ b/tests/ui/imports/import-alias-issue-121168.edition2021.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/import-alias-issue-121168.rs:11:12
    |
 LL |     let _: Foo<i32> = todo!();
@@ -13,4 +13,4 @@ LL + use import_alias_issue_121168_extern::Foo;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/inaccessible_type_aliases.stderr b/tests/ui/imports/inaccessible_type_aliases.stderr
index 9afcfb21487bc..1e463e923fc1c 100644
--- a/tests/ui/imports/inaccessible_type_aliases.stderr
+++ b/tests/ui/imports/inaccessible_type_aliases.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/inaccessible_type_aliases.rs:12:12
    |
 LL |     let x: Foo = 100;
@@ -13,7 +13,7 @@ LL |     type Foo = u64;
 LL |     type Foo = u64;
    |     ^^^^^^^^^^^^^^^ `b::Foo`: not accessible
 
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/inaccessible_type_aliases.rs:13:12
    |
 LL |     let y: Bar = 100;
@@ -27,4 +27,4 @@ LL |     type Bar = u64;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/imports/issue-4366-2.stderr b/tests/ui/imports/issue-4366-2.stderr
index 517a434ebe37b..6736b39a4070c 100644
--- a/tests/ui/imports/issue-4366-2.stderr
+++ b/tests/ui/imports/issue-4366-2.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/issue-4366-2.rs:16:21
    |
 LL |         fn sub() -> Bar { 1 }
@@ -28,5 +28,5 @@ LL + use foo::foo;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0423.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0423, E0425.
+For more information about an error, try `rustc --explain E0423`.
diff --git a/tests/ui/issues/issue-30589.stderr b/tests/ui/issues/issue-30589.stderr
index 6f97a189cead9..43d80896edf8c 100644
--- a/tests/ui/issues/issue-30589.stderr
+++ b/tests/ui/issues/issue-30589.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `DecoderError` in this scope
+error[E0425]: cannot find type `DecoderError` in this scope
   --> $DIR/issue-30589.rs:3:23
    |
 LL | impl fmt::Display for DecoderError {
@@ -6,4 +6,4 @@ LL | impl fmt::Display for DecoderError {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/issues/issue-36836.stderr b/tests/ui/issues/issue-36836.stderr
index e5c943c7c3d82..2d9a97df90520 100644
--- a/tests/ui/issues/issue-36836.stderr
+++ b/tests/ui/issues/issue-36836.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/issue-36836.rs:13:17
    |
 LL | impl<T> Foo for Bar<T> {}
@@ -6,4 +6,4 @@ LL | impl<T> Foo for Bar<T> {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr b/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr
index dd5119318ff4b..b4225a813bd2e 100644
--- a/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr
+++ b/tests/ui/layout/cannot-transmute-unnormalizable-type.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/cannot-transmute-unnormalizable-type.rs:7:5
    |
 LL |     Missing: Trait,
@@ -15,5 +15,5 @@ LL |         std::mem::transmute::<Option<()>, Option<&Other>>(None);
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0512.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0512.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/layout/issue-84108.stderr b/tests/ui/layout/issue-84108.stderr
index 08acc3d3b2579..3d3bc003e21a0 100644
--- a/tests/ui/layout/issue-84108.stderr
+++ b/tests/ui/layout/issue-84108.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `OsStr` in this scope
+error[E0425]: cannot find type `OsStr` in this scope
   --> $DIR/issue-84108.rs:6:24
    |
 LL | static FOO: (dyn AsRef<OsStr>, u8) = ("hello", 42);
@@ -9,7 +9,7 @@ help: consider importing this struct
 LL + use std::ffi::OsStr;
    |
 
-error[E0412]: cannot find type `Path` in this scope
+error[E0425]: cannot find type `Path` in this scope
   --> $DIR/issue-84108.rs:9:14
    |
 LL | const BAR: (&Path, [u8], usize) = ("hello", [], 42);
@@ -40,5 +40,5 @@ LL | const BAR: (&Path, [u8], usize) = ("hello", [], 42);
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0277, E0308, E0412.
+Some errors have detailed explanations: E0277, E0308, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/layout/malformed-unsized-type-in-union.stderr b/tests/ui/layout/malformed-unsized-type-in-union.stderr
index bdfabc0b15190..d819a2b368edb 100644
--- a/tests/ui/layout/malformed-unsized-type-in-union.stderr
+++ b/tests/ui/layout/malformed-unsized-type-in-union.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/malformed-unsized-type-in-union.rs:3:34
    |
 LL | union W { s: dyn Iterator<Item = Missing> }
@@ -18,5 +18,5 @@ LL | union W { s: std::mem::ManuallyDrop<dyn Iterator<Item = Missing>> }
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0740.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0740.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/layout/thaw-transmute-invalid-enum.stderr b/tests/ui/layout/thaw-transmute-invalid-enum.stderr
index 2b89159c26336..f57f0a2ad6981 100644
--- a/tests/ui/layout/thaw-transmute-invalid-enum.stderr
+++ b/tests/ui/layout/thaw-transmute-invalid-enum.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Subset` in this scope
+error[E0425]: cannot find type `Subset` in this scope
   --> $DIR/thaw-transmute-invalid-enum.rs:35:41
    |
 LL |     assert::is_transmutable::<Superset, Subset>();
@@ -75,5 +75,5 @@ LL |         a: std::mem::ManuallyDrop<Ox00>,
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0412, E0517, E0658, E0740.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0517, E0658, E0740.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/layout/transmute-to-tail-with-err.stderr b/tests/ui/layout/transmute-to-tail-with-err.stderr
index cff408127179f..484ab5aebd18f 100644
--- a/tests/ui/layout/transmute-to-tail-with-err.stderr
+++ b/tests/ui/layout/transmute-to-tail-with-err.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/transmute-to-tail-with-err.rs:3:26
    |
 LL | struct Bar(Box<dyn Trait<T>>);
@@ -20,5 +20,5 @@ LL |     let x: Bar = unsafe { std::mem::transmute(()) };
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0512.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0512.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/lifetimes/elided-lifetime-in-const-param-type.stderr b/tests/ui/lifetimes/elided-lifetime-in-const-param-type.stderr
index c7f3c0cc0cd6e..d8d867be507a0 100644
--- a/tests/ui/lifetimes/elided-lifetime-in-const-param-type.stderr
+++ b/tests/ui/lifetimes/elided-lifetime-in-const-param-type.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `c` in this scope
+error[E0425]: cannot find type `c` in this scope
   --> $DIR/elided-lifetime-in-const-param-type.rs:8:27
    |
 LL | type A = dyn for<const B: c(&())> D;
@@ -16,5 +16,5 @@ LL | type A = dyn for<const B: c(&())> D;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0658.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0658.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr b/tests/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr
index e57933da558fd..a44c9c316984f 100644
--- a/tests/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr
+++ b/tests/ui/lifetimes/issue-83907-invalid-fn-like-path.stderr
@@ -6,7 +6,7 @@ LL | static STATIC_VAR_FIVE: &One();
    |                               |
    |                               help: provide a definition for the static: `= <expr>;`
 
-error[E0412]: cannot find type `One` in this scope
+error[E0425]: cannot find type `One` in this scope
   --> $DIR/issue-83907-invalid-fn-like-path.rs:3:26
    |
 LL | static STATIC_VAR_FIVE: &One();
@@ -14,4 +14,4 @@ LL | static STATIC_VAR_FIVE: &One();
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/lint/issue-35075.stderr b/tests/ui/lint/issue-35075.stderr
index f1f27152c2ff5..427095132daf3 100644
--- a/tests/ui/lint/issue-35075.stderr
+++ b/tests/ui/lint/issue-35075.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/issue-35075.rs:3:12
    |
 LL |     inner: Foo<T>
@@ -10,7 +10,7 @@ LL -     inner: Foo<T>
 LL +     inner: Baz
    |
 
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/issue-35075.rs:7:9
    |
 LL |     Foo(Foo<T>)
@@ -24,4 +24,4 @@ LL +     Foo(Baz)
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/lint/recommend-literal.rs b/tests/ui/lint/recommend-literal.rs
index 453cbf28569e9..45f9ae0a7bdfb 100644
--- a/tests/ui/lint/recommend-literal.rs
+++ b/tests/ui/lint/recommend-literal.rs
@@ -8,10 +8,10 @@ fn main() {
     //~^ ERROR cannot find type `long` in this scope
     //~| HELP perhaps you intended to use this type
     let v1: Boolean = true;
-    //~^ ERROR: cannot find type `Boolean` in this scope [E0412]
+    //~^ ERROR: cannot find type `Boolean` in this scope [E0425]
     //~| HELP perhaps you intended to use this type
     let v2: Bool = true;
-    //~^ ERROR: cannot find type `Bool` in this scope [E0412]
+    //~^ ERROR: cannot find type `Bool` in this scope [E0425]
     //~| HELP a builtin type with a similar name exists
     //~| HELP perhaps you intended to use this type
 }
diff --git a/tests/ui/lint/recommend-literal.stderr b/tests/ui/lint/recommend-literal.stderr
index 263071ca9a754..6b6dd134e1d29 100644
--- a/tests/ui/lint/recommend-literal.stderr
+++ b/tests/ui/lint/recommend-literal.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `double` in this scope
+error[E0425]: cannot find type `double` in this scope
   --> $DIR/recommend-literal.rs:1:13
    |
 LL | type Real = double;
@@ -7,7 +7,7 @@ LL | type Real = double;
    |             not found in this scope
    |             help: perhaps you intended to use this type: `f64`
 
-error[E0412]: cannot find type `long` in this scope
+error[E0425]: cannot find type `long` in this scope
   --> $DIR/recommend-literal.rs:7:12
    |
 LL |     let y: long = 74802374902374923;
@@ -16,7 +16,7 @@ LL |     let y: long = 74802374902374923;
    |            not found in this scope
    |            help: perhaps you intended to use this type: `i64`
 
-error[E0412]: cannot find type `Boolean` in this scope
+error[E0425]: cannot find type `Boolean` in this scope
   --> $DIR/recommend-literal.rs:10:13
    |
 LL |     let v1: Boolean = true;
@@ -25,7 +25,7 @@ LL |     let v1: Boolean = true;
    |             not found in this scope
    |             help: perhaps you intended to use this type: `bool`
 
-error[E0412]: cannot find type `Bool` in this scope
+error[E0425]: cannot find type `Bool` in this scope
   --> $DIR/recommend-literal.rs:13:13
    |
 LL |     let v2: Bool = true;
@@ -42,7 +42,7 @@ LL -     let v2: Bool = true;
 LL +     let v2: bool = true;
    |
 
-error[E0412]: cannot find type `boolean` in this scope
+error[E0425]: cannot find type `boolean` in this scope
   --> $DIR/recommend-literal.rs:19:9
    |
 LL | fn z(a: boolean) {
@@ -51,7 +51,7 @@ LL | fn z(a: boolean) {
    |         not found in this scope
    |         help: perhaps you intended to use this type: `bool`
 
-error[E0412]: cannot find type `byte` in this scope
+error[E0425]: cannot find type `byte` in this scope
   --> $DIR/recommend-literal.rs:24:11
    |
 LL | fn a() -> byte {
@@ -60,7 +60,7 @@ LL | fn a() -> byte {
    |           not found in this scope
    |           help: perhaps you intended to use this type: `u8`
 
-error[E0412]: cannot find type `float` in this scope
+error[E0425]: cannot find type `float` in this scope
   --> $DIR/recommend-literal.rs:31:12
    |
 LL |     width: float,
@@ -69,7 +69,7 @@ LL |     width: float,
    |            not found in this scope
    |            help: perhaps you intended to use this type: `f32`
 
-error[E0412]: cannot find type `int` in this scope
+error[E0425]: cannot find type `int` in this scope
   --> $DIR/recommend-literal.rs:34:19
    |
 LL |     depth: Option<int>,
@@ -85,7 +85,7 @@ help: you might be missing a type parameter
 LL | struct Data<int> {
    |            +++++
 
-error[E0412]: cannot find type `short` in this scope
+error[E0425]: cannot find type `short` in this scope
   --> $DIR/recommend-literal.rs:40:16
    |
 LL | impl Stuff for short {}
@@ -96,4 +96,4 @@ LL | impl Stuff for short {}
 
 error: aborting due to 9 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/lint/use_suggestion_json.stderr b/tests/ui/lint/use_suggestion_json.stderr
index 20975864341db..6f2d7b461f76b 100644
--- a/tests/ui/lint/use_suggestion_json.stderr
+++ b/tests/ui/lint/use_suggestion_json.stderr
@@ -2,71 +2,67 @@
   "$message_type": "diagnostic",
   "message": "cannot find type `Iter` in this scope",
   "code": {
-    "code": "E0412",
-    "explanation": "A used type name is not in scope.
+    "code": "E0425",
+    "explanation": "An unresolved name was used.
 
 Erroneous code examples:
 
-```compile_fail,E0412
-impl Something {} // error: type name `Something` is not in scope
+```compile_fail,E0425
+something_that_doesnt_exist::foo;
+// error: unresolved name `something_that_doesnt_exist::foo`
 
 // or:
 
 trait Foo {
-    fn bar(N); // error: type name `N` is not in scope
+    fn bar() {
+        Self; // error: unresolved name `Self`
+    }
 }
 
 // or:
 
-fn foo(x: T) {} // type name `T` is not in scope
+let x = unknown_variable;  // error: unresolved name `unknown_variable`
 ```
 
-To fix this error, please verify you didn't misspell the type name, you did
-declare it or imported it into the scope. Examples:
+Please verify that the name wasn't misspelled and ensure that the
+identifier being referred to is valid for the given situation. Example:
 
 ```
-struct Something;
-
-impl Something {} // ok!
-
-// or:
-
-trait Foo {
-    type N;
-
-    fn bar(_: Self::N); // ok!
+enum something_that_does_exist {
+    Foo,
 }
+```
 
-// or:
+Or:
 
-fn foo<T>(x: T) {} // ok!
 ```
+mod something_that_does_exist {
+    pub static foo : i32 = 0i32;
+}
 
-Another case that causes this error is when a type is imported into a parent
-module. To fix this, you can follow the suggestion and use File directly or
-`use super::File;` which will import the types from the parent namespace. An
-example that causes this error is below:
+something_that_does_exist::foo; // ok!
+```
 
-```compile_fail,E0412
-use std::fs::File;
+Or:
 
-mod foo {
-    fn some_function(f: File) {}
-}
 ```
-
+let unknown_variable = 12u32;
+let x = unknown_variable; // ok!
 ```
-use std::fs::File;
 
-mod foo {
-    // either
-    use super::File;
-    // or
-    // use std::fs::File;
-    fn foo(f: File) {}
-}
-# fn main() {} // don't insert it for us; that'll break imports
+If the item is not defined in the current module, it must be imported using a
+`use` statement, like so:
+
 ```
+# mod foo { pub fn bar() {} }
+# fn main() {
+use foo::bar;
+bar();
+# }
+```
+
+If the item you are importing is not defined in some super-module of the
+current module, then it must also be declared as public (e.g., `pub fn`).
 "
   },
   "level": "error",
@@ -403,7 +399,7 @@ mod foo {
       "rendered": null
     }
   ],
-  "rendered": "\u001b[1m\u001b[91merror[E0412]\u001b[0m\u001b[1m: cannot find type `Iter` in this scope\u001b[0m
+  "rendered": "\u001b[1m\u001b[91merror[E0425]\u001b[0m\u001b[1m: cannot find type `Iter` in this scope\u001b[0m
   \u001b[1m\u001b[94m--> \u001b[0m$DIR/use_suggestion_json.rs:13:12
    \u001b[1m\u001b[94m|\u001b[0m
 \u001b[1m\u001b[94mLL\u001b[0m \u001b[1m\u001b[94m|\u001b[0m     let x: Iter;
@@ -436,11 +432,11 @@ mod foo {
 }
 {
   "$message_type": "diagnostic",
-  "message": "For more information about this error, try `rustc --explain E0412`.",
+  "message": "For more information about this error, try `rustc --explain E0425`.",
   "code": null,
   "level": "failure-note",
   "spans": [],
   "children": [],
-  "rendered": "\u001b[1mFor more information about this error, try `rustc --explain E0412`.\u001b[0m
+  "rendered": "\u001b[1mFor more information about this error, try `rustc --explain E0425`.\u001b[0m
 "
 }
diff --git a/tests/ui/macros/macro-context.stderr b/tests/ui/macros/macro-context.stderr
index 2efc0b136bc14..edddfef9de3b2 100644
--- a/tests/ui/macros/macro-context.stderr
+++ b/tests/ui/macros/macro-context.stderr
@@ -42,7 +42,7 @@ LL |     m!();
    |
    = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `i` in this scope
+error[E0425]: cannot find type `i` in this scope
   --> $DIR/macro-context.rs:3:13
    |
 LL |     () => ( i ; typeof );
@@ -80,8 +80,7 @@ LL |     let i = m!();
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
 Future incompatibility report: Future breakage diagnostic:
 error: trailing semicolon in macro used in expression position
   --> $DIR/macro-context.rs:3:15
diff --git a/tests/ui/match/issue-82866.stderr b/tests/ui/match/issue-82866.stderr
index f9e3360a525ff..f2b63c6a0ea50 100644
--- a/tests/ui/match/issue-82866.stderr
+++ b/tests/ui/match/issue-82866.stderr
@@ -4,7 +4,7 @@ error[E0425]: cannot find value `x` in this scope
 LL |     match x {
    |           ^ not found in this scope
 
-error[E0412]: cannot find type `v` in this scope
+error[E0425]: cannot find type `v` in this scope
   --> $DIR/issue-82866.rs:4:16
    |
 LL |         Some::<v>(v) => (),
@@ -12,5 +12,4 @@ LL |         Some::<v>(v) => (),
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/mir/gvn-nonsensical-coroutine-layout.rs b/tests/ui/mir/gvn-nonsensical-coroutine-layout.rs
index f0d174cd01b0a..1b387b3820e4a 100644
--- a/tests/ui/mir/gvn-nonsensical-coroutine-layout.rs
+++ b/tests/ui/mir/gvn-nonsensical-coroutine-layout.rs
@@ -4,7 +4,7 @@
 
 pub enum Request {
     TestSome(T),
-    //~^ ERROR cannot find type `T` in this scope [E0412]
+    //~^ ERROR cannot find type `T` in this scope [E0425]
 }
 
 pub async fn handle_event(event: Request) {
diff --git a/tests/ui/mir/gvn-nonsensical-coroutine-layout.stderr b/tests/ui/mir/gvn-nonsensical-coroutine-layout.stderr
index abc7b16ca7415..c22c996160e5a 100644
--- a/tests/ui/mir/gvn-nonsensical-coroutine-layout.stderr
+++ b/tests/ui/mir/gvn-nonsensical-coroutine-layout.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/gvn-nonsensical-coroutine-layout.rs:6:14
    |
 LL |     TestSome(T),
@@ -22,5 +22,5 @@ LL + use std::error::Request;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0574.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0574.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/mir/issue-83499-input-output-iteration-ice.stderr b/tests/ui/mir/issue-83499-input-output-iteration-ice.stderr
index 5c5936d48e31d..2ce695ce79d93 100644
--- a/tests/ui/mir/issue-83499-input-output-iteration-ice.stderr
+++ b/tests/ui/mir/issue-83499-input-output-iteration-ice.stderr
@@ -4,7 +4,7 @@ error: at least one trait must be specified
 LL | unsafe extern "C" fn foo(_: Bar, _: ...) -> impl {}
    |                                             ^^^^
 
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/issue-83499-input-output-iteration-ice.rs:7:29
    |
 LL | unsafe extern "C" fn foo(_: Bar, _: ...) -> impl {}
@@ -12,4 +12,4 @@ LL | unsafe extern "C" fn foo(_: Bar, _: ...) -> impl {}
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/mir/meaningless-bound.stderr b/tests/ui/mir/meaningless-bound.stderr
index dc08def83b665..73f8f9dcbcdb6 100644
--- a/tests/ui/mir/meaningless-bound.stderr
+++ b/tests/ui/mir/meaningless-bound.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `b` in this scope
+error[E0425]: cannot find type `b` in this scope
   --> $DIR/meaningless-bound.rs:6:5
    |
 LL |     b: Sized,
@@ -15,5 +15,5 @@ LL |     Self: Sized,
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0411, E0412.
+Some errors have detailed explanations: E0411, E0425.
 For more information about an error, try `rustc --explain E0411`.
diff --git a/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-1.stderr b/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-1.stderr
index 468da0227d3d0..8c8f1ad85d28a 100644
--- a/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-1.stderr
+++ b/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-1.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `B` in this scope
+error[E0425]: cannot find type `B` in this scope
   --> $DIR/mir-build-2021-closure-capture-ice-110453-1.rs:12:18
    |
 LL |     pub struct C(B);
@@ -11,4 +11,4 @@ LL +     use crate::B;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-2.stderr b/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-2.stderr
index 8fe4981eb3f24..10505991de97b 100644
--- a/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-2.stderr
+++ b/tests/ui/mir/mir-build-2021-closure-capture-ice-110453-2.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `as_str` in this scope
+error[E0425]: cannot find type `as_str` in this scope
   --> $DIR/mir-build-2021-closure-capture-ice-110453-2.rs:8:47
    |
 LL | pub fn dup(f: impl Fn(i32) -> i32) -> impl Fn(as_str) -> i32 {
@@ -6,4 +6,4 @@ LL | pub fn dup(f: impl Fn(i32) -> i32) -> impl Fn(as_str) -> i32 {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/missing/missing-items/missing-type-parameter2.stderr b/tests/ui/missing/missing-items/missing-type-parameter2.stderr
index 3c132e769eaef..c361ed79cc799 100644
--- a/tests/ui/missing/missing-items/missing-type-parameter2.stderr
+++ b/tests/ui/missing/missing-items/missing-type-parameter2.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/missing-type-parameter2.rs:3:8
    |
 LL | struct X<const N: u8>();
@@ -17,7 +17,7 @@ help: you might be missing a type parameter
 LL | impl<N> X<N> {}
    |     +++
 
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/missing-type-parameter2.rs:6:28
    |
 LL | impl<T, const A: u8 = 2> X<N> {}
@@ -35,7 +35,7 @@ help: you might be missing a type parameter
 LL | impl<T, const A: u8 = 2, N> X<N> {}
    |                        +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/missing-type-parameter2.rs:11:20
    |
 LL | struct X<const N: u8>();
@@ -54,7 +54,7 @@ help: you might be missing a type parameter
 LL | fn foo<T>(_: T) where T: Send {}
    |       +++
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/missing-type-parameter2.rs:11:11
    |
 LL | struct X<const N: u8>();
@@ -73,7 +73,7 @@ help: you might be missing a type parameter
 LL | fn foo<T>(_: T) where T: Send {}
    |       +++
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/missing-type-parameter2.rs:15:24
    |
 LL | struct X<const N: u8>();
@@ -122,5 +122,5 @@ LL | impl<T, const A: u8 = 2> X<{ N }> {}
 
 error: aborting due to 8 previous errors
 
-Some errors have detailed explanations: E0412, E0747.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0747.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/offset-of/offset-of-enum.stderr b/tests/ui/offset-of/offset-of-enum.stderr
index 362296a22e8fe..cc1b1aa10d244 100644
--- a/tests/ui/offset-of/offset-of-enum.stderr
+++ b/tests/ui/offset-of/offset-of-enum.stderr
@@ -7,7 +7,7 @@ LL |     offset_of!(Alpha::One, 0);
    |                not a type
    |                help: try using the variant's enum: `Alpha`
 
-error[E0412]: cannot find type `Beta` in this scope
+error[E0425]: cannot find type `Beta` in this scope
   --> $DIR/offset-of-enum.rs:18:16
    |
 LL |     offset_of!(Beta, One);
@@ -43,5 +43,5 @@ LL |     offset_of!(Alpha, NonExistent);
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0412, E0573, E0599, E0609, E0795.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0573, E0599, E0609, E0795.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/offset-of/offset-of-self.stderr b/tests/ui/offset-of/offset-of-self.stderr
index 57afb6b9282ea..cd78fe492b807 100644
--- a/tests/ui/offset-of/offset-of-self.stderr
+++ b/tests/ui/offset-of/offset-of-self.stderr
@@ -4,7 +4,7 @@ error: offset_of expects dot-separated field and variant names
 LL |         offset_of!(Self, Self::v);
    |                          ^^^^^^^
 
-error[E0412]: cannot find type `S` in module `self`
+error[E0425]: cannot find type `S` in module `self`
   --> $DIR/offset-of-self.rs:33:26
    |
 LL |         offset_of!(self::S, v);
@@ -59,5 +59,5 @@ LL |     offset_of!(S, v.self);
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0411, E0412, E0609, E0616.
+Some errors have detailed explanations: E0411, E0425, E0609, E0616.
 For more information about an error, try `rustc --explain E0411`.
diff --git a/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr b/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr
index 81ba66c42faa3..bf9ad85dfc5c6 100644
--- a/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr
+++ b/tests/ui/parallel-rustc/ty-variance-issue-124423.stderr
@@ -237,7 +237,7 @@ help: consider introducing lifetime `'a` here
 LL | fn elided4<'a>(_: &impl Copy + 'a) ->  new  { x(x) }
    |           ++++
 
-error[E0412]: cannot find type `new` in this scope
+error[E0425]: cannot find type `new` in this scope
   --> $DIR/ty-variance-issue-124423.rs:48:36
    |
 LL | fn elided4(_: &impl Copy + 'a) ->  new  { x(x) }
@@ -282,5 +282,5 @@ note: if you're trying to build a new `Box<_, _>` consider using one of the foll
 
 error: aborting due to 30 previous errors
 
-Some errors have detailed explanations: E0121, E0224, E0261, E0412, E0599.
-For more information about an error, try `rustc --explain E0121`.
\ No newline at end of file
+Some errors have detailed explanations: E0121, E0224, E0261, E0425, E0599.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/tests/ui/parser/associated-path-shl.stderr b/tests/ui/parser/associated-path-shl.stderr
index 71ee93f4835fb..42b7c6a73aef2 100644
--- a/tests/ui/parser/associated-path-shl.stderr
+++ b/tests/ui/parser/associated-path-shl.stderr
@@ -1,28 +1,28 @@
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-path-shl.rs:4:14
    |
 LL |     let _: <<A>::B>::C;
    |              ^ not found in this scope
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-path-shl.rs:5:15
    |
 LL |     let _ = <<A>::B>::C;
    |               ^ not found in this scope
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-path-shl.rs:6:11
    |
 LL |     let <<A>::B>::C;
    |           ^ not found in this scope
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-path-shl.rs:7:17
    |
 LL |     let 0 ..= <<A>::B>::C;
    |                 ^ not found in this scope
 
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/associated-path-shl.rs:8:7
    |
 LL |     <<A>::B>::C;
@@ -30,4 +30,4 @@ LL |     <<A>::B>::C;
 
 error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/parser/const-param-decl-on-type-instead-of-impl.stderr b/tests/ui/parser/const-param-decl-on-type-instead-of-impl.stderr
index 855163e3d3bd3..db7c76dc1aa95 100644
--- a/tests/ui/parser/const-param-decl-on-type-instead-of-impl.stderr
+++ b/tests/ui/parser/const-param-decl-on-type-instead-of-impl.stderr
@@ -30,7 +30,7 @@ LL |     path::path::Struct::<const N: usize>()
    |
    = help: you might be missing a crate named `path`
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/const-param-decl-on-type-instead-of-impl.rs:8:15
    |
 LL | fn banana(a: <T<const N: usize>>::BAR) {}
@@ -46,5 +46,5 @@ LL |     let _: () = 42;
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0308, E0412, E0433.
+Some errors have detailed explanations: E0308, E0425, E0433.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/parser/dyn-trait-compatibility.stderr b/tests/ui/parser/dyn-trait-compatibility.stderr
index a57c033c1e13d..d15bf3c97f659 100644
--- a/tests/ui/parser/dyn-trait-compatibility.stderr
+++ b/tests/ui/parser/dyn-trait-compatibility.stderr
@@ -1,28 +1,28 @@
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:3:11
    |
 LL | type A0 = dyn;
    |           ^^^ not found in this scope
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:7:11
    |
 LL | type A2 = dyn<dyn, dyn>;
    |           ^^^ not found in this scope
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:7:15
    |
 LL | type A2 = dyn<dyn, dyn>;
    |               ^^^ not found in this scope
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:7:20
    |
 LL | type A2 = dyn<dyn, dyn>;
    |                    ^^^ not found in this scope
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:11:11
    |
 LL | type A3 = dyn<<dyn as dyn>::dyn>;
@@ -34,7 +34,7 @@ error[E0405]: cannot find trait `dyn` in this scope
 LL | type A3 = dyn<<dyn as dyn>::dyn>;
    |                       ^^^ not found in this scope
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/dyn-trait-compatibility.rs:11:16
    |
 LL | type A3 = dyn<<dyn as dyn>::dyn>;
@@ -50,5 +50,5 @@ LL | type A1 = dyn::dyn;
 
 error: aborting due to 8 previous errors
 
-Some errors have detailed explanations: E0405, E0412, E0433.
+Some errors have detailed explanations: E0405, E0425, E0433.
 For more information about an error, try `rustc --explain E0405`.
diff --git a/tests/ui/parser/fn-field-parse-error-ice.stderr b/tests/ui/parser/fn-field-parse-error-ice.stderr
index 6f033e2b0c6ff..74ab1b004ccb6 100644
--- a/tests/ui/parser/fn-field-parse-error-ice.stderr
+++ b/tests/ui/parser/fn-field-parse-error-ice.stderr
@@ -17,7 +17,7 @@ help: escape `fn` to use it as an identifier
 LL |     inner : dyn r#fn ()
    |                 ++
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/fn-field-parse-error-ice.rs:5:13
    |
 LL |     inner : dyn fn ()
@@ -25,4 +25,4 @@ LL |     inner : dyn fn ()
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/parser/recover/recover-fn-ptr-with-generics.stderr b/tests/ui/parser/recover/recover-fn-ptr-with-generics.stderr
index 9023856ef2486..b69e07cc3a1a4 100644
--- a/tests/ui/parser/recover/recover-fn-ptr-with-generics.stderr
+++ b/tests/ui/parser/recover/recover-fn-ptr-with-generics.stderr
@@ -88,13 +88,13 @@ error: expected identifier, found `>`
 LL |     type QuiteBroken = fn<const>();
    |                                ^ expected identifier
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/recover-fn-ptr-with-generics.rs:5:27
    |
 LL |     type Identity = fn<T>(T) -> T;
    |                           ^ not found in this scope
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/recover-fn-ptr-with-generics.rs:5:33
    |
 LL |     type Identity = fn<T>(T) -> T;
@@ -108,4 +108,4 @@ LL |     let _: extern "C" fn<'a: 'static>();
 
 error: aborting due to 12 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/parser/unmatched-langle-1.rs b/tests/ui/parser/unmatched-langle-1.rs
index fdf2ae398014b..51072c13ba5b9 100644
--- a/tests/ui/parser/unmatched-langle-1.rs
+++ b/tests/ui/parser/unmatched-langle-1.rs
@@ -5,5 +5,5 @@ fn main() {
     foo::<<<<Ty<i32>>();
     //~^ ERROR: unmatched angle brackets
     //~| ERROR: cannot find function `foo` in this scope [E0425]
-    //~| ERROR: cannot find type `Ty` in this scope [E0412]
+    //~| ERROR: cannot find type `Ty` in this scope [E0425]
 }
diff --git a/tests/ui/parser/unmatched-langle-1.stderr b/tests/ui/parser/unmatched-langle-1.stderr
index 3411a05fb589a..efe6c9b33210f 100644
--- a/tests/ui/parser/unmatched-langle-1.stderr
+++ b/tests/ui/parser/unmatched-langle-1.stderr
@@ -10,7 +10,7 @@ LL -     foo::<<<<Ty<i32>>();
 LL +     foo::<Ty<i32>>();
    |
 
-error[E0412]: cannot find type `Ty` in this scope
+error[E0425]: cannot find type `Ty` in this scope
   --> $DIR/unmatched-langle-1.rs:5:14
    |
 LL |     foo::<<<<Ty<i32>>();
@@ -24,5 +24,4 @@ LL |     foo::<<<<Ty<i32>>();
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/parser/where_with_bound.stderr b/tests/ui/parser/where_with_bound.stderr
index 06b611e1cd009..1e490f2ddcd19 100644
--- a/tests/ui/parser/where_with_bound.stderr
+++ b/tests/ui/parser/where_with_bound.stderr
@@ -4,7 +4,7 @@ error: generic parameters on `where` clauses are reserved for future use
 LL | fn foo<T>() where <T>::Item: ToString, T: Iterator { }
    |                   ^^^ currently unsupported
 
-error[E0412]: cannot find type `Item` in the crate root
+error[E0425]: cannot find type `Item` in the crate root
   --> $DIR/where_with_bound.rs:2:24
    |
 LL | fn foo<T>() where <T>::Item: ToString, T: Iterator { }
@@ -12,4 +12,4 @@ LL | fn foo<T>() where <T>::Item: ToString, T: Iterator { }
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/pattern/usefulness/issue-119493-type-error-ice.stderr b/tests/ui/pattern/usefulness/issue-119493-type-error-ice.stderr
index 1c560aa2ca813..06e13aa2ea01d 100644
--- a/tests/ui/pattern/usefulness/issue-119493-type-error-ice.stderr
+++ b/tests/ui/pattern/usefulness/issue-119493-type-error-ice.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `NonExistent` in this scope
+error[E0425]: cannot find type `NonExistent` in this scope
   --> $DIR/issue-119493-type-error-ice.rs:5:16
    |
 LL |     struct Foo(NonExistent);
    |                ^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `NonExistent` in this scope
+error[E0425]: cannot find type `NonExistent` in this scope
   --> $DIR/issue-119493-type-error-ice.rs:5:16
    |
 LL |     struct Foo(NonExistent);
@@ -27,5 +27,5 @@ LL |     type U = impl Copy;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0658.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0658.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/privacy/privacy-ns1.stderr b/tests/ui/privacy/privacy-ns1.stderr
index 58e276a75a712..dd4a1e93020bb 100644
--- a/tests/ui/privacy/privacy-ns1.stderr
+++ b/tests/ui/privacy/privacy-ns1.stderr
@@ -52,7 +52,7 @@ help: consider importing this function
 LL + use foo2::Bar;
    |
 
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/privacy-ns1.rs:53:17
    |
 LL |     pub struct Baz;
@@ -90,5 +90,5 @@ LL |     let _x: Box<Bar>;
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0412, E0423, E0425, E0747.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0423, E0425, E0747.
+For more information about an error, try `rustc --explain E0423`.
diff --git a/tests/ui/privacy/sysroot-private.default.stderr b/tests/ui/privacy/sysroot-private.default.stderr
index 692b1bbd4db35..66712a59e7b27 100644
--- a/tests/ui/privacy/sysroot-private.default.stderr
+++ b/tests/ui/privacy/sysroot-private.default.stderr
@@ -4,7 +4,7 @@ error[E0405]: cannot find trait `Equivalent` in this scope
 LL | trait Trait2<K>: Equivalent<K> {}
    |                  ^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `K` in this scope
+error[E0425]: cannot find type `K` in this scope
   --> $DIR/sysroot-private.rs:32:35
    |
 LL | fn trait_member<T>(val: &T, key: &K) -> bool {
@@ -36,5 +36,5 @@ LL |     memchr2(b'a', b'b', buf)
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0220, E0405, E0412, E0425.
+Some errors have detailed explanations: E0220, E0405, E0425.
 For more information about an error, try `rustc --explain E0220`.
diff --git a/tests/ui/privacy/sysroot-private.rustc_private_enabled.stderr b/tests/ui/privacy/sysroot-private.rustc_private_enabled.stderr
index dc2d890a082cf..94b85b995c479 100644
--- a/tests/ui/privacy/sysroot-private.rustc_private_enabled.stderr
+++ b/tests/ui/privacy/sysroot-private.rustc_private_enabled.stderr
@@ -4,7 +4,7 @@ error[E0405]: cannot find trait `Equivalent` in this scope
 LL | trait Trait2<K>: Equivalent<K> {}
    |                  ^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `K` in this scope
+error[E0425]: cannot find type `K` in this scope
   --> $DIR/sysroot-private.rs:32:35
    |
 LL | fn trait_member<T>(val: &T, key: &K) -> bool {
@@ -36,5 +36,5 @@ LL |     memchr2(b'a', b'b', buf)
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0220, E0405, E0412, E0425.
+Some errors have detailed explanations: E0220, E0405, E0425.
 For more information about an error, try `rustc --explain E0220`.
diff --git a/tests/ui/proc-macro/attributes-on-modules-fail.stderr b/tests/ui/proc-macro/attributes-on-modules-fail.stderr
index 74c797aacd9ea..1dc87fd0d5513 100644
--- a/tests/ui/proc-macro/attributes-on-modules-fail.stderr
+++ b/tests/ui/proc-macro/attributes-on-modules-fail.stderr
@@ -46,7 +46,7 @@ LL |     mod inner;
    = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0412]: cannot find type `Y` in this scope
+error[E0425]: cannot find type `Y` in this scope
   --> $DIR/attributes-on-modules-fail.rs:11:14
    |
 LL |     type A = Y;
@@ -57,7 +57,7 @@ help: consider importing this struct
 LL +     use Y;
    |
 
-error[E0412]: cannot find type `X` in this scope
+error[E0425]: cannot find type `X` in this scope
   --> $DIR/attributes-on-modules-fail.rs:15:10
    |
 LL | type A = X;
@@ -70,5 +70,5 @@ LL + use m::X;
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0412, E0658, E0774.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0658, E0774.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/proc-macro/empty-where-clause.stderr b/tests/ui/proc-macro/empty-where-clause.stderr
index 192a2b30f0dcd..5588ed5f36e21 100644
--- a/tests/ui/proc-macro/empty-where-clause.stderr
+++ b/tests/ui/proc-macro/empty-where-clause.stderr
@@ -1,16 +1,16 @@
-error[E0412]: cannot find type `MissingType1` in this scope
+error[E0425]: cannot find type `MissingType1` in this scope
   --> $DIR/empty-where-clause.rs:8:12
    |
 LL |     field: MissingType1
    |            ^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `MissingType2` in this scope
+error[E0425]: cannot find type `MissingType2` in this scope
   --> $DIR/empty-where-clause.rs:12:20
    |
 LL | struct TupleStruct(MissingType2) where;
    |                    ^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `MissingType3` in this scope
+error[E0425]: cannot find type `MissingType3` in this scope
   --> $DIR/empty-where-clause.rs:15:13
    |
 LL |     Variant(MissingType3)
@@ -18,4 +18,4 @@ LL |     Variant(MissingType3)
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/proc-macro/generate-mod.stderr b/tests/ui/proc-macro/generate-mod.stderr
index 47210c63c2b29..af90df2c3dc3b 100644
--- a/tests/ui/proc-macro/generate-mod.stderr
+++ b/tests/ui/proc-macro/generate-mod.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `FromOutside` in this scope
+error[E0425]: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:11:1
    |
 LL | generate_mod::check!();
@@ -8,7 +8,7 @@ LL | generate_mod::check!();
            FromOutside
    = note: this error originates in the macro `generate_mod::check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `Outer` in this scope
+error[E0425]: cannot find type `Outer` in this scope
   --> $DIR/generate-mod.rs:11:1
    |
 LL | generate_mod::check!();
@@ -18,7 +18,7 @@ LL | generate_mod::check!();
            Outer
    = note: this error originates in the macro `generate_mod::check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `FromOutside` in this scope
+error[E0425]: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:14:1
    |
 LL | #[generate_mod::check_attr]
@@ -28,7 +28,7 @@ LL | #[generate_mod::check_attr]
            FromOutside
    = note: this error originates in the attribute macro `generate_mod::check_attr` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `OuterAttr` in this scope
+error[E0425]: cannot find type `OuterAttr` in this scope
   --> $DIR/generate-mod.rs:14:1
    |
 LL | #[generate_mod::check_attr]
@@ -81,7 +81,7 @@ LL |     #[derive(generate_mod::CheckDerive)]
 
 error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
 Future incompatibility report: Future breakage diagnostic:
 error: cannot find type `FromOutside` in this scope
   --> $DIR/generate-mod.rs:18:10
diff --git a/tests/ui/proc-macro/issue-83510.stderr b/tests/ui/proc-macro/issue-83510.stderr
index 50209a8facb9a..755d6e3a03ee5 100644
--- a/tests/ui/proc-macro/issue-83510.stderr
+++ b/tests/ui/proc-macro/issue-83510.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/issue-83510.rs:7:1
    |
 LL | issue_83510::dance_like_you_want_to_ice!();
@@ -35,5 +35,5 @@ LL | issue_83510::dance_like_you_want_to_ice!();
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0404, E0405, E0412, E0658.
+Some errors have detailed explanations: E0404, E0405, E0425, E0658.
 For more information about an error, try `rustc --explain E0404`.
diff --git a/tests/ui/proc-macro/macro-rules-derive.stderr b/tests/ui/proc-macro/macro-rules-derive.stderr
index e7cd4474618fe..05ad9e559ad1c 100644
--- a/tests/ui/proc-macro/macro-rules-derive.stderr
+++ b/tests/ui/proc-macro/macro-rules-derive.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/macro-rules-derive.rs:10:20
    |
 LL |             field: MissingType
@@ -11,4 +11,4 @@ LL | produce_it!(MyName);
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/proc-macro/mixed-site-span.stderr b/tests/ui/proc-macro/mixed-site-span.stderr
index b215ef03dc785..d5cf484f6dd0e 100644
--- a/tests/ui/proc-macro/mixed-site-span.stderr
+++ b/tests/ui/proc-macro/mixed-site-span.stderr
@@ -576,7 +576,7 @@ LL |         proc_macro_rules!();
    |
    = note: this error originates in the macro `proc_macro_rules` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `ItemUse` in crate `$crate`
+error[E0425]: cannot find type `ItemUse` in crate `$crate`
   --> $DIR/mixed-site-span.rs:23:9
    |
 LL |         proc_macro_rules!();
@@ -609,5 +609,5 @@ LL |         local_def;
 
 error: aborting due to 52 previous errors
 
-Some errors have detailed explanations: E0412, E0425, E0426, E0432.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0426, E0432.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/proc-macro/span-from-proc-macro.stderr b/tests/ui/proc-macro/span-from-proc-macro.stderr
index 945a5620fac48..0605c727733b2 100644
--- a/tests/ui/proc-macro/span-from-proc-macro.stderr
+++ b/tests/ui/proc-macro/span-from-proc-macro.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/auxiliary/span-from-proc-macro.rs:33:20
    |
 LL | pub fn error_from_attribute(_args: TokenStream, _input: TokenStream) -> TokenStream {
@@ -12,7 +12,7 @@ LL |             field: MissingType
 LL | #[error_from_attribute]
    | ----------------------- in this attribute macro expansion
 
-error[E0412]: cannot find type `OtherMissingType` in this scope
+error[E0425]: cannot find type `OtherMissingType` in this scope
   --> $DIR/auxiliary/span-from-proc-macro.rs:42:21
    |
 LL | pub fn error_from_derive(_input: TokenStream) -> TokenStream {
@@ -58,5 +58,5 @@ LL |     error_from_bang!();
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0308, E0412, E0425.
+Some errors have detailed explanations: E0308, E0425.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/recursion/recursive-reexports.stderr b/tests/ui/recursion/recursive-reexports.stderr
index 71653d26a18d7..04805d145fee1 100644
--- a/tests/ui/recursion/recursive-reexports.stderr
+++ b/tests/ui/recursion/recursive-reexports.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `S` in crate `recursive_reexports`
+error[E0425]: cannot find type `S` in crate `recursive_reexports`
   --> $DIR/recursive-reexports.rs:5:32
    |
 LL | fn f() -> recursive_reexports::S {}
@@ -6,4 +6,4 @@ LL | fn f() -> recursive_reexports::S {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/regions/outlives-with-missing.stderr b/tests/ui/regions/outlives-with-missing.stderr
index 0e3aaaf5fdbd0..b8762e9cb8f3e 100644
--- a/tests/ui/regions/outlives-with-missing.stderr
+++ b/tests/ui/regions/outlives-with-missing.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/outlives-with-missing.rs:10:9
    |
 LL | impl<H: HandlerFamily> HandlerWrapper<H> {
@@ -9,4 +9,4 @@ LL |         T: Send + Sync + 'static,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/dont-compute-arg-names-for-non-fn.stderr b/tests/ui/resolve/dont-compute-arg-names-for-non-fn.stderr
index a1a8bb575e14a..01a3293b73610 100644
--- a/tests/ui/resolve/dont-compute-arg-names-for-non-fn.stderr
+++ b/tests/ui/resolve/dont-compute-arg-names-for-non-fn.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/dont-compute-arg-names-for-non-fn.rs:8:14
    |
 LL | impl Foo for Bar {}
@@ -11,4 +11,4 @@ LL | impl Foo for Self::Bar {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/editions-crate-root-2015.stderr b/tests/ui/resolve/editions-crate-root-2015.stderr
index 3d203c8ed9676..989ee547a7c6c 100644
--- a/tests/ui/resolve/editions-crate-root-2015.stderr
+++ b/tests/ui/resolve/editions-crate-root-2015.stderr
@@ -20,13 +20,13 @@ help: you might be missing a crate named `nonexistant`, add it to your project a
 LL + extern crate nonexistant;
    |
 
-error[E0412]: cannot find type `nonexistant` in the crate root
+error[E0425]: cannot find type `nonexistant` in the crate root
   --> $DIR/editions-crate-root-2015.rs:11:25
    |
 LL |     fn bare_global(_: ::nonexistant) {
    |                         ^^^^^^^^^^^ not found in the crate root
 
-error[E0412]: cannot find type `nonexistant` in the crate root
+error[E0425]: cannot find type `nonexistant` in the crate root
   --> $DIR/editions-crate-root-2015.rs:14:29
    |
 LL |     fn bare_crate(_: crate::nonexistant) {
@@ -34,5 +34,5 @@ LL |     fn bare_crate(_: crate::nonexistant) {
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0412, E0433.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0433.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/editions-crate-root-2018.stderr b/tests/ui/resolve/editions-crate-root-2018.stderr
index 967a5a2fca155..1bcef33961994 100644
--- a/tests/ui/resolve/editions-crate-root-2018.stderr
+++ b/tests/ui/resolve/editions-crate-root-2018.stderr
@@ -10,13 +10,13 @@ error[E0433]: failed to resolve: could not find `nonexistant` in the crate root
 LL |     fn crate_inner(_: crate::nonexistant::Foo) {
    |                              ^^^^^^^^^^^ could not find `nonexistant` in the crate root
 
-error[E0412]: cannot find crate `nonexistant` in the list of imported crates
+error[E0425]: cannot find crate `nonexistant` in the list of imported crates
   --> $DIR/editions-crate-root-2018.rs:11:25
    |
 LL |     fn bare_global(_: ::nonexistant) {
    |                         ^^^^^^^^^^^ not found in the list of imported crates
 
-error[E0412]: cannot find type `nonexistant` in the crate root
+error[E0425]: cannot find type `nonexistant` in the crate root
   --> $DIR/editions-crate-root-2018.rs:14:29
    |
 LL |     fn bare_crate(_: crate::nonexistant) {
@@ -24,5 +24,5 @@ LL |     fn bare_crate(_: crate::nonexistant) {
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0412, E0433.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0433.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/issue-21221-1.rs b/tests/ui/resolve/issue-21221-1.rs
index 690feab2b2e13..881bcabd73ac6 100644
--- a/tests/ui/resolve/issue-21221-1.rs
+++ b/tests/ui/resolve/issue-21221-1.rs
@@ -46,7 +46,7 @@ impl Mul for Foo {
 }
 
 // BEFORE, we got:
-//   error: use of undeclared type name `Mul` [E0412]
+//   error: use of undeclared type name `Mul` [E0425]
 // AFTER, we get:
 //   error: type name `Mul` is not in scope. Maybe you meant:
 //   help: ...
diff --git a/tests/ui/resolve/issue-21221-1.stderr b/tests/ui/resolve/issue-21221-1.stderr
index 7537d91fe8dc1..c1716f18de86c 100644
--- a/tests/ui/resolve/issue-21221-1.stderr
+++ b/tests/ui/resolve/issue-21221-1.stderr
@@ -13,7 +13,7 @@ LL + use mul1::Mul;
 LL + use mul2::Mul;
    |
 
-error[E0412]: cannot find type `Mul` in this scope
+error[E0425]: cannot find type `Mul` in this scope
   --> $DIR/issue-21221-1.rs:59:16
    |
 LL | fn getMul() -> Mul {
@@ -58,5 +58,5 @@ LL + use std::ops::Div;
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0405, E0412.
+Some errors have detailed explanations: E0405, E0425.
 For more information about an error, try `rustc --explain E0405`.
diff --git a/tests/ui/resolve/issue-35675.stderr b/tests/ui/resolve/issue-35675.stderr
index 994d0fa6a7553..6a6db22f89ee0 100644
--- a/tests/ui/resolve/issue-35675.stderr
+++ b/tests/ui/resolve/issue-35675.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Apple` in this scope
+error[E0425]: cannot find type `Apple` in this scope
   --> $DIR/issue-35675.rs:8:29
    |
 LL | fn should_return_fruit() -> Apple {
@@ -50,7 +50,7 @@ LL | fn foo() -> Ok {
    |             not a type
    |             help: try using the variant's enum: `std::result::Result`
 
-error[E0412]: cannot find type `Variant3` in this scope
+error[E0425]: cannot find type `Variant3` in this scope
   --> $DIR/issue-35675.rs:25:13
    |
 LL | fn bar() -> Variant3 {
@@ -73,5 +73,5 @@ LL | fn qux() -> Some {
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0412, E0425, E0573.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0573.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.rs b/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.rs
index c377ecea94d0c..235eae9f517ab 100644
--- a/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.rs
+++ b/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.rs
@@ -2,5 +2,5 @@ fn main() {}
 
 trait Foo {
     fn fn_with_type_named_same_as_local_in_param(b: b);
-    //~^ ERROR cannot find type `b` in this scope [E0412]
+    //~^ ERROR cannot find type `b` in this scope [E0425]
 }
diff --git a/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.stderr b/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.stderr
index 60ef13551a17c..1db2a0a707b03 100644
--- a/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.stderr
+++ b/tests/ui/resolve/issue-69401-trait-fn-no-body-ty-local.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `b` in this scope
+error[E0425]: cannot find type `b` in this scope
   --> $DIR/issue-69401-trait-fn-no-body-ty-local.rs:4:53
    |
 LL |     fn fn_with_type_named_same_as_local_in_param(b: b);
@@ -6,4 +6,4 @@ LL |     fn fn_with_type_named_same_as_local_in_param(b: b);
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/issue-85348.rs b/tests/ui/resolve/issue-85348.rs
index 3a33c19340841..d0704bcddef5b 100644
--- a/tests/ui/resolve/issue-85348.rs
+++ b/tests/ui/resolve/issue-85348.rs
@@ -1,7 +1,7 @@
 // Checks whether shadowing a const parameter leads to an ICE (#85348).
 
 impl<const N: usize> ArrayWindowsExample {
-//~^ ERROR: cannot find type `ArrayWindowsExample` in this scope [E0412]
+//~^ ERROR: cannot find type `ArrayWindowsExample` in this scope [E0425]
     fn next() {
         let mut N;
         //~^ ERROR: let bindings cannot shadow const parameters [E0530]
diff --git a/tests/ui/resolve/issue-85348.stderr b/tests/ui/resolve/issue-85348.stderr
index 42b43f825d10c..bf44a570ab8c0 100644
--- a/tests/ui/resolve/issue-85348.stderr
+++ b/tests/ui/resolve/issue-85348.stderr
@@ -7,7 +7,7 @@ LL | impl<const N: usize> ArrayWindowsExample {
 LL |         let mut N;
    |                 ^ cannot be named the same as a const parameter
 
-error[E0412]: cannot find type `ArrayWindowsExample` in this scope
+error[E0425]: cannot find type `ArrayWindowsExample` in this scope
   --> $DIR/issue-85348.rs:3:22
    |
 LL | impl<const N: usize> ArrayWindowsExample {
@@ -26,5 +26,5 @@ LL |         let mut N: /* Type */;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0282, E0412, E0530.
+Some errors have detailed explanations: E0282, E0425, E0530.
 For more information about an error, try `rustc --explain E0282`.
diff --git a/tests/ui/resolve/issue-88472.rs b/tests/ui/resolve/issue-88472.rs
index df20252b2b408..abc0bda790d66 100644
--- a/tests/ui/resolve/issue-88472.rs
+++ b/tests/ui/resolve/issue-88472.rs
@@ -15,7 +15,7 @@ mod b {
     use crate::a::*;
     //~^ WARNING: unused import
     type Bar = Foo;
-    //~^ ERROR: cannot find type `Foo` in this scope [E0412]
+    //~^ ERROR: cannot find type `Foo` in this scope [E0425]
     //~| NOTE: not found in this scope
 }
 
@@ -32,7 +32,7 @@ mod c {
 
 mod e {
     type Baz = Eee;
-    //~^ ERROR: cannot find type `Eee` in this scope [E0412]
+    //~^ ERROR: cannot find type `Eee` in this scope [E0425]
     //~| NOTE: not found in this scope
 }
 
diff --git a/tests/ui/resolve/issue-88472.stderr b/tests/ui/resolve/issue-88472.stderr
index cfcc0a95cc38c..cca36f32f3937 100644
--- a/tests/ui/resolve/issue-88472.stderr
+++ b/tests/ui/resolve/issue-88472.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/issue-88472.rs:17:16
    |
 LL |     type Bar = Foo;
@@ -10,7 +10,7 @@ note: struct `a::Foo` exists but is inaccessible
 LL |     struct Foo;
    |     ^^^^^^^^^^^ not accessible
 
-error[E0412]: cannot find type `Eee` in this scope
+error[E0425]: cannot find type `Eee` in this scope
   --> $DIR/issue-88472.rs:34:16
    |
 LL |     type Baz = Eee;
@@ -39,4 +39,4 @@ LL | #![warn(unused_imports)]
 
 error: aborting due to 2 previous errors; 1 warning emitted
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/levenshtein.stderr b/tests/ui/resolve/levenshtein.stderr
index 7fc5710c35ecc..7a1abd1343303 100644
--- a/tests/ui/resolve/levenshtein.stderr
+++ b/tests/ui/resolve/levenshtein.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `esize` in this scope
+error[E0425]: cannot find type `esize` in this scope
   --> $DIR/levenshtein.rs:5:11
    |
 LL | fn foo(c: esize) {} // Misspelled primitive type name.
    |           ^^^^^ help: a builtin type with a similar name exists: `isize`
 
-error[E0412]: cannot find type `Baz` in this scope
+error[E0425]: cannot find type `Baz` in this scope
   --> $DIR/levenshtein.rs:10:10
    |
 LL | enum Bar { }
@@ -13,7 +13,7 @@ LL |
 LL | type A = Baz; // Misspelled type name.
    |          ^^^ help: an enum with a similar name exists: `Bar`
 
-error[E0412]: cannot find type `Opiton` in this scope
+error[E0425]: cannot find type `Opiton` in this scope
   --> $DIR/levenshtein.rs:12:10
    |
 LL | type B = Opiton<u8>; // Misspelled type name from the prelude.
@@ -23,7 +23,7 @@ LL | type B = Opiton<u8>; // Misspelled type name from the prelude.
    |
    = note: similarly named enum `Option` defined here
 
-error[E0412]: cannot find type `Baz` in this scope
+error[E0425]: cannot find type `Baz` in this scope
   --> $DIR/levenshtein.rs:16:14
    |
 LL |     type A = Baz; // No suggestion here, Bar is not visible
@@ -38,7 +38,7 @@ LL | const MAX_ITEM: usize = 10;
 LL |     let v = [0u32; MAXITEM]; // Misspelled constant name.
    |                    ^^^^^^^ help: a constant with a similar name exists: `MAX_ITEM`
 
-error[E0412]: cannot find type `first` in module `m`
+error[E0425]: cannot find type `first` in module `m`
   --> $DIR/levenshtein.rs:28:15
    |
 LL |     pub struct First;
@@ -67,5 +67,4 @@ LL |     foobar(); // Misspelled function name.
 
 error: aborting due to 8 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/missing-type-in-scope-58712.stderr b/tests/ui/resolve/missing-type-in-scope-58712.stderr
index d7e06eee856c9..bd40781230688 100644
--- a/tests/ui/resolve/missing-type-in-scope-58712.stderr
+++ b/tests/ui/resolve/missing-type-in-scope-58712.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `DeviceId` in this scope
+error[E0425]: cannot find type `DeviceId` in this scope
   --> $DIR/missing-type-in-scope-58712.rs:7:20
    |
 LL | impl<H> AddrVec<H, DeviceId> {
@@ -9,7 +9,7 @@ help: you might be missing a type parameter
 LL | impl<H, DeviceId> AddrVec<H, DeviceId> {
    |       ++++++++++
 
-error[E0412]: cannot find type `DeviceId` in this scope
+error[E0425]: cannot find type `DeviceId` in this scope
   --> $DIR/missing-type-in-scope-58712.rs:9:29
    |
 LL |     pub fn device(&self) -> DeviceId {
@@ -17,4 +17,4 @@ LL |     pub fn device(&self) -> DeviceId {
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/privacy-enum-ctor.stderr b/tests/ui/resolve/privacy-enum-ctor.stderr
index 3082674941fd7..81356c5040f8b 100644
--- a/tests/ui/resolve/privacy-enum-ctor.stderr
+++ b/tests/ui/resolve/privacy-enum-ctor.stderr
@@ -142,7 +142,7 @@ LL + use std::f32::consts::E;
 LL + use std::f64::consts::E;
    |
 
-error[E0412]: cannot find type `Z` in this scope
+error[E0425]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:58:12
    |
 LL |     pub enum E {
@@ -185,7 +185,7 @@ LL -     let _: Z = m::n::Z;
 LL +     let _: Z = (m::Z::Fn(/* fields */));
    |
 
-error[E0412]: cannot find type `Z` in this scope
+error[E0425]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:62:12
    |
 LL |     pub enum E {
@@ -200,7 +200,7 @@ note: enum `m::Z` exists but is inaccessible
 LL |         pub(in crate::m) enum Z {
    |         ^^^^^^^^^^^^^^^^^^^^^^^ not accessible
 
-error[E0412]: cannot find type `Z` in this scope
+error[E0425]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:65:12
    |
 LL |     pub enum E {
@@ -215,7 +215,7 @@ note: enum `m::Z` exists but is inaccessible
 LL |         pub(in crate::m) enum Z {
    |         ^^^^^^^^^^^^^^^^^^^^^^^ not accessible
 
-error[E0412]: cannot find type `Z` in this scope
+error[E0425]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:69:12
    |
 LL |     pub enum E {
@@ -433,5 +433,5 @@ LL |     let _: Z = m::n::Z::Struct { s: /* value */ };
 
 error: aborting due to 23 previous errors
 
-Some errors have detailed explanations: E0308, E0412, E0423, E0533, E0603, E0618.
+Some errors have detailed explanations: E0308, E0423, E0425, E0533, E0603, E0618.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/resolve/raw-ident-in-path.stderr b/tests/ui/resolve/raw-ident-in-path.stderr
index 7d2aa69113638..e88465ab89523 100644
--- a/tests/ui/resolve/raw-ident-in-path.stderr
+++ b/tests/ui/resolve/raw-ident-in-path.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `r#break` in the crate root
+error[E0425]: cannot find type `r#break` in the crate root
   --> $DIR/raw-ident-in-path.rs:3:17
    |
 LL | type A = crate::r#break;
@@ -6,4 +6,4 @@ LL | type A = crate::r#break;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/resolve-assoc-suggestions.stderr b/tests/ui/resolve/resolve-assoc-suggestions.stderr
index 3d9d4ffaa10c8..ef519ac0d9217 100644
--- a/tests/ui/resolve/resolve-assoc-suggestions.stderr
+++ b/tests/ui/resolve/resolve-assoc-suggestions.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `field` in this scope
+error[E0425]: cannot find type `field` in this scope
   --> $DIR/resolve-assoc-suggestions.rs:16:16
    |
 LL |         let _: field;
@@ -21,7 +21,7 @@ help: you might have meant to use the available field
 LL |         self.field;
    |         +++++
 
-error[E0412]: cannot find type `Type` in this scope
+error[E0425]: cannot find type `Type` in this scope
   --> $DIR/resolve-assoc-suggestions.rs:23:16
    |
 LL |         let _: Type;
@@ -44,7 +44,7 @@ error[E0425]: cannot find value `Type` in this scope
 LL |         Type;
    |         ^^^^ not found in this scope
 
-error[E0412]: cannot find type `method` in this scope
+error[E0425]: cannot find type `method` in this scope
   --> $DIR/resolve-assoc-suggestions.rs:30:16
    |
 LL |         let _: method;
@@ -69,5 +69,5 @@ LL |         self.method;
 
 error: aborting due to 9 previous errors
 
-Some errors have detailed explanations: E0412, E0425, E0531.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0531.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/resolve-primitive-fallback.stderr b/tests/ui/resolve/resolve-primitive-fallback.stderr
index f9ab55913d148..17b8cf805de29 100644
--- a/tests/ui/resolve/resolve-primitive-fallback.stderr
+++ b/tests/ui/resolve/resolve-primitive-fallback.stderr
@@ -4,7 +4,7 @@ error[E0423]: expected value, found builtin type `u16`
 LL |     std::mem::size_of(u16);
    |                       ^^^ not a value
 
-error[E0412]: cannot find type `u8` in the crate root
+error[E0425]: cannot find type `u8` in the crate root
   --> $DIR/resolve-primitive-fallback.rs:9:14
    |
 LL |     let _: ::u8;
@@ -36,5 +36,5 @@ LL +     std::mem::size_of();
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0061, E0412, E0423.
+Some errors have detailed explanations: E0061, E0423, E0425.
 For more information about an error, try `rustc --explain E0061`.
diff --git a/tests/ui/resolve/typo-suggestion-for-variable-with-name-similar-to-struct-field.stderr b/tests/ui/resolve/typo-suggestion-for-variable-with-name-similar-to-struct-field.stderr
index 1ecbfee17bc70..039410f8795f8 100644
--- a/tests/ui/resolve/typo-suggestion-for-variable-with-name-similar-to-struct-field.stderr
+++ b/tests/ui/resolve/typo-suggestion-for-variable-with-name-similar-to-struct-field.stderr
@@ -61,7 +61,7 @@ help: a constant with a similar name exists
 LL |         BARR;
    |            +
 
-error[E0412]: cannot find type `Baz` in this scope
+error[E0425]: cannot find type `Baz` in this scope
   --> $DIR/typo-suggestion-for-variable-with-name-similar-to-struct-field.rs:37:18
    |
 LL |         let foo: Baz = "".to_string();
@@ -101,5 +101,4 @@ LL +         ba();
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/use_suggestion.stderr b/tests/ui/resolve/use_suggestion.stderr
index 1155f5caa1739..9981c97b2c17e 100644
--- a/tests/ui/resolve/use_suggestion.stderr
+++ b/tests/ui/resolve/use_suggestion.stderr
@@ -9,7 +9,7 @@ help: consider importing this struct
 LL + use std::collections::HashMap;
    |
 
-error[E0412]: cannot find type `HashMap` in this scope
+error[E0425]: cannot find type `HashMap` in this scope
   --> $DIR/use_suggestion.rs:5:13
    |
 LL |     let y1: HashMap;
@@ -20,7 +20,7 @@ help: consider importing this struct
 LL + use std::collections::HashMap;
    |
 
-error[E0412]: cannot find type `GooMap` in this scope
+error[E0425]: cannot find type `GooMap` in this scope
   --> $DIR/use_suggestion.rs:6:13
    |
 LL |     let y2: GooMap;
@@ -34,5 +34,5 @@ LL |     let x2 = GooMap::new();
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0412, E0433.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0433.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/resolve/use_suggestion_placement.stderr b/tests/ui/resolve/use_suggestion_placement.stderr
index e92a230ad7653..85ad256657687 100644
--- a/tests/ui/resolve/use_suggestion_placement.stderr
+++ b/tests/ui/resolve/use_suggestion_placement.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Path` in this scope
+error[E0425]: cannot find type `Path` in this scope
   --> $DIR/use_suggestion_placement.rs:19:16
    |
 LL |     type Bar = Path;
@@ -20,7 +20,7 @@ help: consider importing this constant
 LL + use m::A;
    |
 
-error[E0412]: cannot find type `HashMap` in this scope
+error[E0425]: cannot find type `HashMap` in this scope
   --> $DIR/use_suggestion_placement.rs:29:23
    |
 LL |     type Dict<K, V> = HashMap<K, V>;
@@ -33,5 +33,4 @@ LL + use std::collections::HashMap;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0412, E0425.
-For more information about an error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/self/elision/nested-item.stderr b/tests/ui/self/elision/nested-item.stderr
index 7bad26fa13303..0e6e36a30f9ca 100644
--- a/tests/ui/self/elision/nested-item.stderr
+++ b/tests/ui/self/elision/nested-item.stderr
@@ -35,7 +35,7 @@ LL - fn wrap(self: Wrap<{ fn bar(&self) {} }>) -> &() {
 LL + fn wrap(self: Wrap<{ fn bar(&self) {} }>) -> () {
    |
 
-error[E0412]: cannot find type `Wrap` in this scope
+error[E0425]: cannot find type `Wrap` in this scope
   --> $DIR/nested-item.rs:5:15
    |
 LL | fn wrap(self: Wrap<{ fn bar(&self) {} }>) -> &() {
@@ -43,5 +43,5 @@ LL | fn wrap(self: Wrap<{ fn bar(&self) {} }>) -> &() {
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0106, E0412.
+Some errors have detailed explanations: E0106, E0425.
 For more information about an error, try `rustc --explain E0106`.
diff --git a/tests/ui/sized/ensure-overriding-bindings-in-pattern-with-ty-err-doesnt-ice.stderr b/tests/ui/sized/ensure-overriding-bindings-in-pattern-with-ty-err-doesnt-ice.stderr
index eec2f5b42fda9..d253c7c065b9a 100644
--- a/tests/ui/sized/ensure-overriding-bindings-in-pattern-with-ty-err-doesnt-ice.stderr
+++ b/tests/ui/sized/ensure-overriding-bindings-in-pattern-with-ty-err-doesnt-ice.stderr
@@ -6,7 +6,7 @@ LL |     let str::<{fn str() { let str::T>>::as_bytes; }}, T>::as_bytes;
    |
    = note: arbitrary expressions are not allowed in patterns: <https://doc.rust-lang.org/book/ch19-00-patterns.html>
 
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/ensure-overriding-bindings-in-pattern-with-ty-err-doesnt-ice.rs:2:55
    |
 LL |     let str::<{fn str() { let str::T>>::as_bytes; }}, T>::as_bytes;
@@ -47,5 +47,5 @@ LL |     let str::<{fn str() { let str::T>>::as_bytes: /* Type */; }}, T>::as_by
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0109, E0282, E0412, E0533.
+Some errors have detailed explanations: E0109, E0282, E0425, E0533.
 For more information about an error, try `rustc --explain E0109`.
diff --git a/tests/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-96258.stderr b/tests/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-96258.stderr
index 00b9a81b27d99..b2380f4ba2739 100644
--- a/tests/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-96258.stderr
+++ b/tests/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-96258.stderr
@@ -7,7 +7,7 @@ LL |     pub(crate) async fn new(
    = help: pass `--edition 2024` to `rustc`
    = note: for more on editions, read https://doc.rust-lang.org/edition-guide
 
-error[E0412]: cannot find type `Duration` in this scope
+error[E0425]: cannot find type `Duration` in this scope
   --> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-96258.rs:12:19
    |
 LL |         interval: Duration,
@@ -20,5 +20,5 @@ LL + use std::time::Duration;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0412, E0670.
-For more information about an error, try `rustc --explain E0412`.
+Some errors have detailed explanations: E0425, E0670.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/specialization/issue-68830-spurious-diagnostics.stderr b/tests/ui/specialization/issue-68830-spurious-diagnostics.stderr
index 0ecec03a023eb..f668fda119c2a 100644
--- a/tests/ui/specialization/issue-68830-spurious-diagnostics.stderr
+++ b/tests/ui/specialization/issue-68830-spurious-diagnostics.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/issue-68830-spurious-diagnostics.rs:8:10
    |
 LL |     err: MissingType
@@ -6,4 +6,4 @@ LL |     err: MissingType
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/specialization/min_specialization/impl-on-nonexisting.stderr b/tests/ui/specialization/min_specialization/impl-on-nonexisting.stderr
index 85b492c0503b2..a531d07d97c55 100644
--- a/tests/ui/specialization/min_specialization/impl-on-nonexisting.stderr
+++ b/tests/ui/specialization/min_specialization/impl-on-nonexisting.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `NonExistent` in this scope
+error[E0425]: cannot find type `NonExistent` in this scope
   --> $DIR/impl-on-nonexisting.rs:4:16
    |
 LL | impl Trait for NonExistent {}
@@ -6,4 +6,4 @@ LL | impl Trait for NonExistent {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/structs/ice-struct-tail-normalization-113272.stderr b/tests/ui/structs/ice-struct-tail-normalization-113272.stderr
index 8c55dbca18719..9663f93c169b4 100644
--- a/tests/ui/structs/ice-struct-tail-normalization-113272.stderr
+++ b/tests/ui/structs/ice-struct-tail-normalization-113272.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/ice-struct-tail-normalization-113272.rs:5:25
    |
 LL | impl Trait for () where Missing: Trait {}
@@ -24,5 +24,5 @@ LL |         std::mem::transmute::<Option<()>, Option<&Other>>(None);
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0046, E0412, E0512.
+Some errors have detailed explanations: E0046, E0425, E0512.
 For more information about an error, try `rustc --explain E0046`.
diff --git a/tests/ui/suggestions/assoc-type-in-method-return.stderr b/tests/ui/suggestions/assoc-type-in-method-return.stderr
index f83da79097009..23a2fd5c504e4 100644
--- a/tests/ui/suggestions/assoc-type-in-method-return.stderr
+++ b/tests/ui/suggestions/assoc-type-in-method-return.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Bla` in this scope
+error[E0425]: cannot find type `Bla` in this scope
   --> $DIR/assoc-type-in-method-return.rs:3:25
    |
 LL |     fn to_bla(&self) -> Bla;
@@ -11,4 +11,4 @@ LL |     fn to_bla(&self) -> Self::Bla;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.rs b/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.rs
index e53932f79003c..e7ce2b38b1b26 100644
--- a/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.rs
+++ b/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.rs
@@ -9,16 +9,16 @@ mod local {
 }
 
 pub fn test(_: Foo) {}
-//~^ ERROR [E0412]
+//~^ ERROR [E0425]
 
 pub fn test2(_: Bar) {}
-//~^ ERROR [E0412]
+//~^ ERROR [E0425]
 
 pub fn test3(_: Baz) {}
-//~^ ERROR [E0412]
+//~^ ERROR [E0425]
 
 pub fn test4(_: Quux) {}
-//~^ ERROR [E0412]
+//~^ ERROR [E0425]
 
 fn test5<T: hidden_struct::Marker>() {}
 
diff --git a/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.stderr b/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.stderr
index 5ac336b0c3e20..623bc723eb6ce 100644
--- a/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.stderr
+++ b/tests/ui/suggestions/dont-suggest-foreign-doc-hidden.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/dont-suggest-foreign-doc-hidden.rs:11:16
    |
 LL | pub fn test(_: Foo) {}
@@ -9,13 +9,13 @@ help: consider importing this struct
 LL + use local::Foo;
    |
 
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/dont-suggest-foreign-doc-hidden.rs:14:17
    |
 LL | pub fn test2(_: Bar) {}
    |                 ^^^ not found in this scope
 
-error[E0412]: cannot find type `Baz` in this scope
+error[E0425]: cannot find type `Baz` in this scope
   --> $DIR/dont-suggest-foreign-doc-hidden.rs:17:17
    |
 LL | pub fn test3(_: Baz) {}
@@ -26,7 +26,7 @@ help: consider importing this struct
 LL + use hidden_struct::Baz;
    |
 
-error[E0412]: cannot find type `Quux` in this scope
+error[E0425]: cannot find type `Quux` in this scope
   --> $DIR/dont-suggest-foreign-doc-hidden.rs:20:17
    |
 LL | pub fn test4(_: Quux) {}
@@ -83,5 +83,5 @@ LL | fn test6<T: hidden_struct::library::Marker>() {}
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/suggestions/no-extern-crate-in-type.stderr b/tests/ui/suggestions/no-extern-crate-in-type.stderr
index 384b17d1e2b48..6e71b351d1b54 100644
--- a/tests/ui/suggestions/no-extern-crate-in-type.stderr
+++ b/tests/ui/suggestions/no-extern-crate-in-type.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/no-extern-crate-in-type.rs:5:22
    |
 LL | type Output = Option<Foo>;
@@ -11,4 +11,4 @@ LL + use foo::Foo;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/suggestions/type-not-found-in-adt-field.stderr b/tests/ui/suggestions/type-not-found-in-adt-field.stderr
index 934ba87bbaa88..7d8c6433eb5ae 100644
--- a/tests/ui/suggestions/type-not-found-in-adt-field.stderr
+++ b/tests/ui/suggestions/type-not-found-in-adt-field.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Someunknownname` in this scope
+error[E0425]: cannot find type `Someunknownname` in this scope
   --> $DIR/type-not-found-in-adt-field.rs:2:12
    |
 LL |     m: Vec<Someunknownname<String, ()>>,
    |            ^^^^^^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `K` in this scope
+error[E0425]: cannot find type `K` in this scope
   --> $DIR/type-not-found-in-adt-field.rs:6:8
    |
 LL |     m: K,
@@ -17,4 +17,4 @@ LL | struct OtherStruct<K> {
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/trait-bounds/ice-unsized-struct-arg-issue-121612.stderr b/tests/ui/trait-bounds/ice-unsized-struct-arg-issue-121612.stderr
index 0be80e9479f0b..c70d4cefe9398 100644
--- a/tests/ui/trait-bounds/ice-unsized-struct-arg-issue-121612.stderr
+++ b/tests/ui/trait-bounds/ice-unsized-struct-arg-issue-121612.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Idx` in this scope
+error[E0425]: cannot find type `Idx` in this scope
   --> $DIR/ice-unsized-struct-arg-issue-121612.rs:5:30
    |
 LL | struct MySlice<T: FnOnce(&T, Idx) -> Idx>(bool, T);
    |                              ^^^ not found in this scope
 
-error[E0412]: cannot find type `Idx` in this scope
+error[E0425]: cannot find type `Idx` in this scope
   --> $DIR/ice-unsized-struct-arg-issue-121612.rs:5:38
    |
 LL | struct MySlice<T: FnOnce(&T, Idx) -> Idx>(bool, T);
@@ -53,5 +53,5 @@ LL | struct MySlice<T: FnOnce(&T, Idx) -> Idx>(bool, T);
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/trait-bounds/impl-bound-with-references-error.rs b/tests/ui/trait-bounds/impl-bound-with-references-error.rs
index 5ba35da83839e..6213f74329420 100644
--- a/tests/ui/trait-bounds/impl-bound-with-references-error.rs
+++ b/tests/ui/trait-bounds/impl-bound-with-references-error.rs
@@ -10,7 +10,7 @@ impl<T> From<T> for LabelText
 //~^ ERROR conflicting implementations of trait `From<LabelText>` for type `LabelText` [E0119]
 where
     T: Into<Cow<'static, str>>,
-    //~^ ERROR cannot find type `Cow` in this scope [E0412]
+    //~^ ERROR cannot find type `Cow` in this scope [E0425]
 {
     fn from(text: T) -> Self {
         LabelText::Plain(text.into()) //~ ERROR expected function, found `LabelText`
diff --git a/tests/ui/trait-bounds/impl-bound-with-references-error.stderr b/tests/ui/trait-bounds/impl-bound-with-references-error.stderr
index b3ac5544e38f5..ca8a575e2caa8 100644
--- a/tests/ui/trait-bounds/impl-bound-with-references-error.stderr
+++ b/tests/ui/trait-bounds/impl-bound-with-references-error.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Cow` in this scope
+error[E0425]: cannot find type `Cow` in this scope
   --> $DIR/impl-bound-with-references-error.rs:12:13
    |
 LL |     T: Into<Cow<'static, str>>,
@@ -34,5 +34,5 @@ LL |         LabelText::Plain(text.into())
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0119, E0412, E0618.
+Some errors have detailed explanations: E0119, E0425, E0618.
 For more information about an error, try `rustc --explain E0119`.
diff --git a/tests/ui/traits/duplicate-generic-parameter-error-86756.stderr b/tests/ui/traits/duplicate-generic-parameter-error-86756.stderr
index e761d15ff6708..16043d868e07f 100644
--- a/tests/ui/traits/duplicate-generic-parameter-error-86756.stderr
+++ b/tests/ui/traits/duplicate-generic-parameter-error-86756.stderr
@@ -6,7 +6,7 @@ LL | trait Foo<T, T = T> {}
    |           |
    |           first use of `T`
 
-error[E0412]: cannot find type `dyn` in this scope
+error[E0425]: cannot find type `dyn` in this scope
   --> $DIR/duplicate-generic-parameter-error-86756.rs:7:10
    |
 LL |     eq::<dyn, Foo>
@@ -44,5 +44,5 @@ LL |     eq::<dyn, Foo<T>>
 
 error: aborting due to 3 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0107, E0403, E0412.
+Some errors have detailed explanations: E0107, E0403, E0425.
 For more information about an error, try `rustc --explain E0107`.
diff --git a/tests/ui/traits/error-reporting/apit-with-bad-path.stderr b/tests/ui/traits/error-reporting/apit-with-bad-path.stderr
index 19bd5e78b47fa..c4cc000d47531 100644
--- a/tests/ui/traits/error-reporting/apit-with-bad-path.stderr
+++ b/tests/ui/traits/error-reporting/apit-with-bad-path.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Path` in this scope
+error[E0425]: cannot find type `Path` in this scope
   --> $DIR/apit-with-bad-path.rs:3:29
    |
 LL | fn foo(filename: impl AsRef<Path>) {
@@ -11,4 +11,4 @@ LL + use std::path::Path;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/error-reporting/where-clause-with-bad-path.stderr b/tests/ui/traits/error-reporting/where-clause-with-bad-path.stderr
index 1137178f6114b..763898277b8f0 100644
--- a/tests/ui/traits/error-reporting/where-clause-with-bad-path.stderr
+++ b/tests/ui/traits/error-reporting/where-clause-with-bad-path.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Path` in this scope
+error[E0425]: cannot find type `Path` in this scope
   --> $DIR/where-clause-with-bad-path.rs:3:17
    |
 LL | fn foo<T: AsRef<Path>>(filename: T) {
@@ -11,4 +11,4 @@ LL + use std::path::Path;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/ignore-err-impls.stderr b/tests/ui/traits/ignore-err-impls.stderr
index 955e2d7804981..68077c435135c 100644
--- a/tests/ui/traits/ignore-err-impls.stderr
+++ b/tests/ui/traits/ignore-err-impls.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Type` in this scope
+error[E0425]: cannot find type `Type` in this scope
   --> $DIR/ignore-err-impls.rs:6:14
    |
 LL | impl Generic<Type> for S {}
@@ -11,4 +11,4 @@ LL | impl<Type> Generic<Type> for S {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/issue-50480.stderr b/tests/ui/traits/issue-50480.stderr
index ed8c74e9bddcf..32c8b2cf3ac1f 100644
--- a/tests/ui/traits/issue-50480.stderr
+++ b/tests/ui/traits/issue-50480.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/issue-50480.rs:3:12
    |
 LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
@@ -9,13 +9,13 @@ help: you might be missing a type parameter
 LL | struct Foo<N>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |           +++
 
-error[E0412]: cannot find type `NotDefined` in this scope
+error[E0425]: cannot find type `NotDefined` in this scope
   --> $DIR/issue-50480.rs:3:15
    |
 LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |               ^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/issue-50480.rs:3:12
    |
 LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
@@ -26,7 +26,7 @@ help: you might be missing a type parameter
 LL | struct Foo<N>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |           +++
 
-error[E0412]: cannot find type `NotDefined` in this scope
+error[E0425]: cannot find type `NotDefined` in this scope
   --> $DIR/issue-50480.rs:3:15
    |
 LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
@@ -37,7 +37,7 @@ help: you might be missing a type parameter
 LL | struct Foo<NotDefined>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |           ++++++++++++
 
-error[E0412]: cannot find type `N` in this scope
+error[E0425]: cannot find type `N` in this scope
   --> $DIR/issue-50480.rs:14:18
    |
 LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
@@ -55,7 +55,7 @@ help: you might be missing a type parameter
 LL | struct Bar<T, N>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |             +++
 
-error[E0412]: cannot find type `NotDefined` in this scope
+error[E0425]: cannot find type `NotDefined` in this scope
   --> $DIR/issue-50480.rs:14:21
    |
 LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
@@ -128,5 +128,5 @@ LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 
 error: aborting due to 13 previous errors
 
-Some errors have detailed explanations: E0204, E0277, E0412.
+Some errors have detailed explanations: E0204, E0277, E0425.
 For more information about an error, try `rustc --explain E0204`.
diff --git a/tests/ui/traits/issue-75627.stderr b/tests/ui/traits/issue-75627.stderr
index 137985ee04641..0a3fc181aea26 100644
--- a/tests/ui/traits/issue-75627.stderr
+++ b/tests/ui/traits/issue-75627.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/issue-75627.rs:3:26
    |
 LL | unsafe impl Send for Foo<T> {}
@@ -11,4 +11,4 @@ LL | unsafe impl<T> Send for Foo<T> {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/issue-78372.stderr b/tests/ui/traits/issue-78372.stderr
index a1c772f58e1f1..6744281dc34e2 100644
--- a/tests/ui/traits/issue-78372.stderr
+++ b/tests/ui/traits/issue-78372.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `PhantomData` in this scope
+error[E0425]: cannot find type `PhantomData` in this scope
   --> $DIR/issue-78372.rs:2:23
    |
 LL | struct Smaht<T, MISC>(PhantomData);
@@ -9,7 +9,7 @@ help: consider importing this struct
 LL + use std::marker::PhantomData;
    |
 
-error[E0412]: cannot find type `U` in this scope
+error[E0425]: cannot find type `U` in this scope
   --> $DIR/issue-78372.rs:3:31
    |
 LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
@@ -27,7 +27,7 @@ help: you might be missing a type parameter
 LL | impl<T, U> DispatchFromDyn<Smaht<U, MISC>> for T {}
    |       +++
 
-error[E0412]: cannot find type `MISC` in this scope
+error[E0425]: cannot find type `MISC` in this scope
   --> $DIR/issue-78372.rs:3:34
    |
 LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
@@ -73,5 +73,5 @@ LL |     fn foo(self: Smaht<Self, T>);
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0307, E0377, E0412, E0658.
+Some errors have detailed explanations: E0307, E0377, E0425, E0658.
 For more information about an error, try `rustc --explain E0307`.
diff --git a/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr
index 576ede52aff2d..67690a85d53ce 100644
--- a/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr
+++ b/tests/ui/traits/next-solver/dont-normalize-proj-with-error.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `TypeError` in this scope
+error[E0425]: cannot find type `TypeError` in this scope
   --> $DIR/dont-normalize-proj-with-error.rs:17:20
    |
 LL | fn type_error() -> TypeError { todo!() }
@@ -6,4 +6,4 @@ LL | fn type_error() -> TypeError { todo!() }
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/next-solver/issue-118950-root-region.stderr b/tests/ui/traits/next-solver/issue-118950-root-region.stderr
index e934c5cdc7494..74cbb5be02b37 100644
--- a/tests/ui/traits/next-solver/issue-118950-root-region.stderr
+++ b/tests/ui/traits/next-solver/issue-118950-root-region.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/issue-118950-root-region.rs:19:55
    |
 LL | impl<T> Overlap<for<'a> fn(Assoc<'a, T>)> for T where Missing: Overlap<T> {}
@@ -28,5 +28,5 @@ LL | trait ToUnit<'a> {
  WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: AliasTy { args: ['^0.Named(DefId(0:15 ~ issue_118950_root_region[d54f]::{impl#1}::'a)), ?1t], def_id: DefId(0:8 ~ issue_118950_root_region[d54f]::Assoc), .. }
 error: aborting due to 2 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/traits/non_lifetime_binders/binder-defaults-112547.stderr b/tests/ui/traits/non_lifetime_binders/binder-defaults-112547.stderr
index d9e77dec794a7..608e8136d2a82 100644
--- a/tests/ui/traits/non_lifetime_binders/binder-defaults-112547.stderr
+++ b/tests/ui/traits/non_lifetime_binders/binder-defaults-112547.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `V` in this scope
+error[E0425]: cannot find type `V` in this scope
   --> $DIR/binder-defaults-112547.rs:10:4
    |
 LL | }> V: IntoIterator
@@ -37,4 +37,4 @@ LL | | }> V: IntoIterator
 
 error: aborting due to 3 previous errors; 1 warning emitted
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/non_lifetime_binders/binder-defaults-118697.stderr b/tests/ui/traits/non_lifetime_binders/binder-defaults-118697.stderr
index 6b93f52dbfcaa..9dea5b40159a8 100644
--- a/tests/ui/traits/non_lifetime_binders/binder-defaults-118697.stderr
+++ b/tests/ui/traits/non_lifetime_binders/binder-defaults-118697.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `A` in this scope
+error[E0425]: cannot find type `A` in this scope
   --> $DIR/binder-defaults-118697.rs:4:22
    |
 LL | type T = dyn for<V = A(&())> Fn(());
@@ -18,4 +18,4 @@ LL | type T = dyn for<V = A(&())> Fn(());
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/traits/trait-selection-ice-84727.stderr b/tests/ui/traits/trait-selection-ice-84727.stderr
index d4bc4163897c4..c37c267c893ea 100644
--- a/tests/ui/traits/trait-selection-ice-84727.stderr
+++ b/tests/ui/traits/trait-selection-ice-84727.stderr
@@ -1,22 +1,22 @@
-error[E0412]: cannot find type `Color` in this scope
+error[E0425]: cannot find type `Color` in this scope
   --> $DIR/trait-selection-ice-84727.rs:5:17
    |
 LL |     foreground: Color<Fg>,
    |                 ^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Color` in this scope
+error[E0425]: cannot find type `Color` in this scope
   --> $DIR/trait-selection-ice-84727.rs:7:17
    |
 LL |     background: Color<Bg>,
    |                 ^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Color` in this scope
+error[E0425]: cannot find type `Color` in this scope
   --> $DIR/trait-selection-ice-84727.rs:18:16
    |
 LL |     Self: Over<Color<BottomBg>, Cell<NewFg>>,
    |                ^^^^^ not found in this scope
 
-error[E0412]: cannot find type `NewBg` in this scope
+error[E0425]: cannot find type `NewBg` in this scope
   --> $DIR/trait-selection-ice-84727.rs:32:27
    |
 LL |     fn over(self) -> Cell<NewBg> {
@@ -43,5 +43,5 @@ LL |         self.over();
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0308, E0412.
+Some errors have detailed explanations: E0308, E0425.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/transmutability/issue-101739-1.stderr b/tests/ui/transmutability/issue-101739-1.stderr
index 20bc8af47f8d9..8ec3c8508fa93 100644
--- a/tests/ui/transmutability/issue-101739-1.stderr
+++ b/tests/ui/transmutability/issue-101739-1.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Dst` in this scope
+error[E0425]: cannot find type `Dst` in this scope
   --> $DIR/issue-101739-1.rs:8:9
    |
 LL |         Dst: TransmuteFrom<Src, ASSUME_ALIGNMENT>,
@@ -6,4 +6,4 @@ LL |         Dst: TransmuteFrom<Src, ASSUME_ALIGNMENT>,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst.stderr b/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst.stderr
index 9fa376bf4332b..530cfc7e9b18f 100644
--- a/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst.stderr
+++ b/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Dst` in this scope
+error[E0425]: cannot find type `Dst` in this scope
   --> $DIR/unknown_dst.rs:18:36
    |
 LL |     assert::is_transmutable::<Src, Dst>();
@@ -11,4 +11,4 @@ LL | fn should_gracefully_handle_unknown_dst<Dst>() {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.stderr b/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.stderr
index 564aee687a5f9..267f3b55619e0 100644
--- a/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.stderr
+++ b/tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unknown_dst_field.rs:18:27
    |
 LL |     #[repr(C)] struct Dst(Missing);
    |                           ^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unknown_dst_field.rs:24:36
    |
 LL |     #[repr(C)] struct Dst(&'static Missing);
@@ -42,5 +42,5 @@ LL |         Dst: TransmuteFrom<Src>
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/transmutability/malformed-program-gracefulness/unknown_src.stderr b/tests/ui/transmutability/malformed-program-gracefulness/unknown_src.stderr
index f2c7d9e1bcc15..0ee03efef9f88 100644
--- a/tests/ui/transmutability/malformed-program-gracefulness/unknown_src.stderr
+++ b/tests/ui/transmutability/malformed-program-gracefulness/unknown_src.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Src` in this scope
+error[E0425]: cannot find type `Src` in this scope
   --> $DIR/unknown_src.rs:18:31
    |
 LL |     assert::is_transmutable::<Src, Dst>();
@@ -11,4 +11,4 @@ LL | fn should_gracefully_handle_unknown_src<Src>() {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.stderr b/tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.stderr
index 1156391c301c7..e6bb45a34a1df 100644
--- a/tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.stderr
+++ b/tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unknown_src_field.rs:17:27
    |
 LL |     #[repr(C)] struct Src(Missing);
    |                           ^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unknown_src_field.rs:23:36
    |
 LL |     #[repr(C)] struct Src(&'static Missing);
@@ -42,5 +42,5 @@ LL |         Dst: TransmuteFrom<Src>
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0277, E0412.
+Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/tuple/tuple-struct-fields/test.stderr b/tests/ui/tuple/tuple-struct-fields/test.stderr
index bfa0b32fd458a..61dcbde13b57c 100644
--- a/tests/ui/tuple/tuple-struct-fields/test.stderr
+++ b/tests/ui/tuple/tuple-struct-fields/test.stderr
@@ -6,7 +6,7 @@ LL |     struct S2(pub((foo)) ());
    |                         |
    |                         help: missing `,`
 
-error[E0412]: cannot find type `foo` in this scope
+error[E0425]: cannot find type `foo` in this scope
   --> $DIR/test.rs:4:20
    |
 LL |     struct S2(pub((foo)) ());
@@ -14,4 +14,4 @@ LL |     struct S2(pub((foo)) ());
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/tuple/tuple-struct-fields/test2.stderr b/tests/ui/tuple/tuple-struct-fields/test2.stderr
index 784411aba8f8a..53706eb90bbb7 100644
--- a/tests/ui/tuple/tuple-struct-fields/test2.stderr
+++ b/tests/ui/tuple/tuple-struct-fields/test2.stderr
@@ -11,13 +11,13 @@ LL |     define_struct! { (foo) }
    |
    = note: this error originates in the macro `define_struct` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `foo` in this scope
+error[E0425]: cannot find type `foo` in this scope
   --> $DIR/test2.rs:11:23
    |
 LL |     define_struct! { (foo) }
    |                       ^^^ not found in this scope
 
-error[E0412]: cannot find type `foo` in this scope
+error[E0425]: cannot find type `foo` in this scope
   --> $DIR/test2.rs:11:23
    |
 LL |     define_struct! { (foo) }
@@ -27,4 +27,4 @@ LL |     define_struct! { (foo) }
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/tuple/tuple-struct-fields/test3.stderr b/tests/ui/tuple/tuple-struct-fields/test3.stderr
index 00b07c0315292..6a30e4ba5da2a 100644
--- a/tests/ui/tuple/tuple-struct-fields/test3.stderr
+++ b/tests/ui/tuple/tuple-struct-fields/test3.stderr
@@ -11,13 +11,13 @@ LL |     define_struct! { foo }
    |
    = note: this error originates in the macro `define_struct` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0412]: cannot find type `foo` in this scope
+error[E0425]: cannot find type `foo` in this scope
   --> $DIR/test3.rs:11:22
    |
 LL |     define_struct! { foo }
    |                      ^^^ not found in this scope
 
-error[E0412]: cannot find type `foo` in this scope
+error[E0425]: cannot find type `foo` in this scope
   --> $DIR/test3.rs:11:22
    |
 LL |     define_struct! { foo }
@@ -27,4 +27,4 @@ LL |     define_struct! { foo }
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/type-alias-impl-trait/define_opaques_attr/invalid_path.stderr b/tests/ui/type-alias-impl-trait/define_opaques_attr/invalid_path.stderr
index 6b4cd4eac512b..c6c530b41aff5 100644
--- a/tests/ui/type-alias-impl-trait/define_opaques_attr/invalid_path.stderr
+++ b/tests/ui/type-alias-impl-trait/define_opaques_attr/invalid_path.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type alias or associated type with opaqaue types `Boom` in this scope
+error[E0425]: cannot find type alias or associated type with opaqaue types `Boom` in this scope
   --> $DIR/invalid_path.rs:3:17
    |
 LL | #[define_opaque(Boom)]
@@ -6,4 +6,4 @@ LL | #[define_opaque(Boom)]
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/type-alias-impl-trait/nested-impl-trait-in-tait.stderr b/tests/ui/type-alias-impl-trait/nested-impl-trait-in-tait.stderr
index 3a13ab7cb9570..936bdd59cc9bd 100644
--- a/tests/ui/type-alias-impl-trait/nested-impl-trait-in-tait.stderr
+++ b/tests/ui/type-alias-impl-trait/nested-impl-trait-in-tait.stderr
@@ -14,7 +14,7 @@ help: consider introducing lifetime `'db` here
 LL | pub type Tait<'db> = impl Iterator<Item = (&'db LocalKey, impl Iterator)>;
    |              +++++
 
-error[E0412]: cannot find type `LocalKey` in this scope
+error[E0425]: cannot find type `LocalKey` in this scope
   --> $DIR/nested-impl-trait-in-tait.rs:3:44
    |
 LL | pub type Tait = impl Iterator<Item = (&'db LocalKey, impl Iterator)>;
@@ -43,5 +43,5 @@ LL | pub type Tait = impl Iterator<Item = (&'db LocalKey, impl Iterator)>;
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0261, E0412.
+Some errors have detailed explanations: E0261, E0425.
 For more information about an error, try `rustc --explain E0261`.
diff --git a/tests/ui/type/cannot-find-wrapper-with-impl-trait.rs b/tests/ui/type/cannot-find-wrapper-with-impl-trait.rs
index 48ff4c38f7db3..0117f634c85e9 100644
--- a/tests/ui/type/cannot-find-wrapper-with-impl-trait.rs
+++ b/tests/ui/type/cannot-find-wrapper-with-impl-trait.rs
@@ -6,7 +6,7 @@ pub trait A {
 }
 
 fn addition() -> Wrapper<impl A> {}
-//~^ ERROR cannot find type `Wrapper` in this scope [E0412]
+//~^ ERROR cannot find type `Wrapper` in this scope [E0425]
 
 fn main() {
     let res = addition();
diff --git a/tests/ui/type/cannot-find-wrapper-with-impl-trait.stderr b/tests/ui/type/cannot-find-wrapper-with-impl-trait.stderr
index ac7f2e5134a2c..22fd8f99806be 100644
--- a/tests/ui/type/cannot-find-wrapper-with-impl-trait.stderr
+++ b/tests/ui/type/cannot-find-wrapper-with-impl-trait.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Wrapper` in this scope
+error[E0425]: cannot find type `Wrapper` in this scope
   --> $DIR/cannot-find-wrapper-with-impl-trait.rs:8:18
    |
 LL | fn addition() -> Wrapper<impl A> {}
@@ -6,4 +6,4 @@ LL | fn addition() -> Wrapper<impl A> {}
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/type/issue-7607-1.stderr b/tests/ui/type/issue-7607-1.stderr
index 69b6d62e987a4..ac6034da75f1b 100644
--- a/tests/ui/type/issue-7607-1.stderr
+++ b/tests/ui/type/issue-7607-1.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Fo` in this scope
+error[E0425]: cannot find type `Fo` in this scope
   --> $DIR/issue-7607-1.rs:5:6
    |
 LL | impl Fo {
@@ -10,4 +10,4 @@ LL | impl Fo {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/type/type-path-err-node-types.stderr b/tests/ui/type/type-path-err-node-types.stderr
index 8b12aa1a393b2..a9e999f80b3a0 100644
--- a/tests/ui/type/type-path-err-node-types.stderr
+++ b/tests/ui/type/type-path-err-node-types.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Nonexistent` in this scope
+error[E0425]: cannot find type `Nonexistent` in this scope
   --> $DIR/type-path-err-node-types.rs:7:12
    |
 LL |     let _: Nonexistent<u8, Assoc = u16>;
@@ -35,5 +35,5 @@ LL |     let _ = |a: /* Type */, b: _| -> _ { 0 };
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0282, E0412, E0425, E0433, E0576.
+Some errors have detailed explanations: E0282, E0425, E0433, E0576.
 For more information about an error, try `rustc --explain E0282`.
diff --git a/tests/ui/typeck/apit-with-error-type-in-sig.stderr b/tests/ui/typeck/apit-with-error-type-in-sig.stderr
index 6ed9b1f9b8cba..21ae7554d2bb3 100644
--- a/tests/ui/typeck/apit-with-error-type-in-sig.stderr
+++ b/tests/ui/typeck/apit-with-error-type-in-sig.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Bar` in this scope
+error[E0425]: cannot find type `Bar` in this scope
   --> $DIR/apit-with-error-type-in-sig.rs:1:12
    |
 LL | type Foo = Bar;
@@ -6,4 +6,4 @@ LL | type Foo = Bar;
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/autoderef-with-param-env-error.stderr b/tests/ui/typeck/autoderef-with-param-env-error.stderr
index e06be398aa07a..dd4cfa761ce88 100644
--- a/tests/ui/typeck/autoderef-with-param-env-error.stderr
+++ b/tests/ui/typeck/autoderef-with-param-env-error.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `T` in this scope
+error[E0425]: cannot find type `T` in this scope
   --> $DIR/autoderef-with-param-env-error.rs:3:5
    |
 LL |     T: Send,
@@ -11,4 +11,4 @@ LL | fn foo<T>()
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/impl-for-nonexistent-type-error-8767.stderr b/tests/ui/typeck/impl-for-nonexistent-type-error-8767.stderr
index 0e37391a00f7b..354eb4019c65a 100644
--- a/tests/ui/typeck/impl-for-nonexistent-type-error-8767.stderr
+++ b/tests/ui/typeck/impl-for-nonexistent-type-error-8767.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `B` in this scope
+error[E0425]: cannot find type `B` in this scope
   --> $DIR/impl-for-nonexistent-type-error-8767.rs:2:6
    |
 LL | impl B {
@@ -6,4 +6,4 @@ LL | impl B {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/issue-104510-ice.stderr b/tests/ui/typeck/issue-104510-ice.stderr
index 143139b2c089c..5f330a4e685ce 100644
--- a/tests/ui/typeck/issue-104510-ice.stderr
+++ b/tests/ui/typeck/issue-104510-ice.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Oops` in this scope
+error[E0425]: cannot find type `Oops` in this scope
   --> $DIR/issue-104510-ice.rs:4:21
    |
 LL | struct W<T: ?Sized>(Oops);
@@ -6,4 +6,4 @@ LL | struct W<T: ?Sized>(Oops);
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/issue-83693.rs b/tests/ui/typeck/issue-83693.rs
index 68a1416517a73..f78cf7da4a98b 100644
--- a/tests/ui/typeck/issue-83693.rs
+++ b/tests/ui/typeck/issue-83693.rs
@@ -4,16 +4,16 @@
 #![crate_type="lib"]
 
 impl F {
-//~^ ERROR: cannot find type `F` in this scope [E0412]
+//~^ ERROR: cannot find type `F` in this scope [E0425]
     fn call() {
         <Self as Fn(&TestResult)>::call
-        //~^ ERROR: cannot find type `TestResult` in this scope [E0412]
+        //~^ ERROR: cannot find type `TestResult` in this scope [E0425]
         //~| ERROR associated item constraints are not allowed here [E0229]
     }
 }
 
 fn call() {
     <x as Fn(&usize)>::call
-    //~^ ERROR: cannot find type `x` in this scope [E0412]
+    //~^ ERROR: cannot find type `x` in this scope [E0425]
     //~| ERROR: associated item constraints are not allowed here [E0229]
 }
diff --git a/tests/ui/typeck/issue-83693.stderr b/tests/ui/typeck/issue-83693.stderr
index 0359b8af93a37..521288c434022 100644
--- a/tests/ui/typeck/issue-83693.stderr
+++ b/tests/ui/typeck/issue-83693.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `F` in this scope
+error[E0425]: cannot find type `F` in this scope
   --> $DIR/issue-83693.rs:6:6
    |
 LL | impl F {
@@ -8,13 +8,13 @@ LL | impl F {
    |
    = note: similarly named trait `Fn` defined here
 
-error[E0412]: cannot find type `TestResult` in this scope
+error[E0425]: cannot find type `TestResult` in this scope
   --> $DIR/issue-83693.rs:9:22
    |
 LL |         <Self as Fn(&TestResult)>::call
    |                      ^^^^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `x` in this scope
+error[E0425]: cannot find type `x` in this scope
   --> $DIR/issue-83693.rs:16:6
    |
 LL |     <x as Fn(&usize)>::call
@@ -34,5 +34,5 @@ LL |     <x as Fn(&usize)>::call
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0229, E0412.
+Some errors have detailed explanations: E0229, E0425.
 For more information about an error, try `rustc --explain E0229`.
diff --git a/tests/ui/typeck/issue-88844.rs b/tests/ui/typeck/issue-88844.rs
index 116c75aabdbdf..35d110b50262b 100644
--- a/tests/ui/typeck/issue-88844.rs
+++ b/tests/ui/typeck/issue-88844.rs
@@ -4,7 +4,7 @@ struct Struct { value: i32 }
 //~^ NOTE: similarly named struct `Struct` defined here
 
 impl Stuct {
-//~^ ERROR: cannot find type `Stuct` in this scope [E0412]
+//~^ ERROR: cannot find type `Stuct` in this scope [E0425]
 //~| HELP: a struct with a similar name exists
     fn new() -> Self {
         Self { value: 42 }
diff --git a/tests/ui/typeck/issue-88844.stderr b/tests/ui/typeck/issue-88844.stderr
index 68473f65dcf53..a5f4310c34dde 100644
--- a/tests/ui/typeck/issue-88844.stderr
+++ b/tests/ui/typeck/issue-88844.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Stuct` in this scope
+error[E0425]: cannot find type `Stuct` in this scope
   --> $DIR/issue-88844.rs:6:6
    |
 LL | struct Struct { value: i32 }
@@ -9,4 +9,4 @@ LL | impl Stuct {
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/issue-90319.rs b/tests/ui/typeck/issue-90319.rs
index 57e6ac7cf34f5..64b3a27155036 100644
--- a/tests/ui/typeck/issue-90319.rs
+++ b/tests/ui/typeck/issue-90319.rs
@@ -11,7 +11,7 @@ fn get<T>() -> T {
 }
 
 fn main() {
-    let thing = get::<Thing>();//~ERROR cannot find type `Thing` in this scope [E0412]
+    let thing = get::<Thing>();//~ERROR cannot find type `Thing` in this scope [E0425]
     let wrapper = Wrapper(thing);
     Trait::method(&wrapper);
 }
diff --git a/tests/ui/typeck/issue-90319.stderr b/tests/ui/typeck/issue-90319.stderr
index fa18056e802d4..4f427cbb3b003 100644
--- a/tests/ui/typeck/issue-90319.stderr
+++ b/tests/ui/typeck/issue-90319.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Thing` in this scope
+error[E0425]: cannot find type `Thing` in this scope
   --> $DIR/issue-90319.rs:14:23
    |
 LL |     let thing = get::<Thing>();
@@ -6,4 +6,4 @@ LL |     let thing = get::<Thing>();
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/issue-91267.rs b/tests/ui/typeck/issue-91267.rs
index 1bffa09e64360..22198532b0c91 100644
--- a/tests/ui/typeck/issue-91267.rs
+++ b/tests/ui/typeck/issue-91267.rs
@@ -2,7 +2,7 @@
 
 fn main() {
     type_ascribe!(0, u8<e<5>=e>)
-    //~^ ERROR: cannot find type `e` in this scope [E0412]
+    //~^ ERROR: cannot find type `e` in this scope [E0425]
     //~| ERROR: associated item constraints are not allowed here [E0229]
     //~| ERROR: mismatched types [E0308]
 }
diff --git a/tests/ui/typeck/issue-91267.stderr b/tests/ui/typeck/issue-91267.stderr
index d16b1997e9f7d..0c186f546df26 100644
--- a/tests/ui/typeck/issue-91267.stderr
+++ b/tests/ui/typeck/issue-91267.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `e` in this scope
+error[E0425]: cannot find type `e` in this scope
   --> $DIR/issue-91267.rs:4:30
    |
 LL |     type_ascribe!(0, u8<e<5>=e>)
@@ -22,5 +22,5 @@ LL |     type_ascribe!(0, u8<e<5>=e>)
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0229, E0308, E0412.
+Some errors have detailed explanations: E0229, E0308, E0425.
 For more information about an error, try `rustc --explain E0229`.
diff --git a/tests/ui/typeck/nonexistent-field-not-ambiguous.stderr b/tests/ui/typeck/nonexistent-field-not-ambiguous.stderr
index 82207a731b962..3d876b0228979 100644
--- a/tests/ui/typeck/nonexistent-field-not-ambiguous.stderr
+++ b/tests/ui/typeck/nonexistent-field-not-ambiguous.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `MissingType` in this scope
+error[E0425]: cannot find type `MissingType` in this scope
   --> $DIR/nonexistent-field-not-ambiguous.rs:2:10
    |
 LL |     val: MissingType,
@@ -6,4 +6,4 @@ LL |     val: MissingType,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.rs b/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.rs
index 5aa2bd7fddeb1..28aefdd8d3e4a 100644
--- a/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.rs
+++ b/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.rs
@@ -26,7 +26,7 @@ macro_rules! eq_local {
 
 pub fn foo<I: Iterator>(mut iter: I, value: &I::Item)
 where
-    Item: Eq + Debug, //~ ERROR cannot find type `Item` in this scope [E0412]
+    Item: Eq + Debug, //~ ERROR cannot find type `Item` in this scope [E0425]
 {
     ext::eq!(assert iter.next(), Some(value)); //~ ERROR  mismatched types [E0308]
     eq_local!(assert iter.next(), Some(value));
diff --git a/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.stderr b/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.stderr
index 96a3bc65dfdc9..d74372c665a45 100644
--- a/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.stderr
+++ b/tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Item` in this scope
+error[E0425]: cannot find type `Item` in this scope
   --> $DIR/sugg-swap-equality-in-macro-issue-139050.rs:29:5
    |
 LL |     Item: Eq + Debug,
@@ -35,5 +35,5 @@ LL +                 if !(*right_val == *left_val) {
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0412.
+Some errors have detailed explanations: E0308, E0425.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/union/unresolved-field-isnt-copy.stderr b/tests/ui/union/unresolved-field-isnt-copy.stderr
index ee5d1e37b141c..5ac9e0e9162ab 100644
--- a/tests/ui/union/unresolved-field-isnt-copy.stderr
+++ b/tests/ui/union/unresolved-field-isnt-copy.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/unresolved-field-isnt-copy.rs:4:15
    |
 LL |     x: *const Missing,
@@ -6,4 +6,4 @@ LL |     x: *const Missing,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/variance/type-resolve-error-two-structs-deep.stderr b/tests/ui/variance/type-resolve-error-two-structs-deep.stderr
index 3458d924bb153..2b4f3b5b11157 100644
--- a/tests/ui/variance/type-resolve-error-two-structs-deep.stderr
+++ b/tests/ui/variance/type-resolve-error-two-structs-deep.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/type-resolve-error-two-structs-deep.rs:5:14
    |
 LL |     missing: Missing<'a>,
@@ -6,4 +6,4 @@ LL |     missing: Missing<'a>,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/wf/issue-110157.stderr b/tests/ui/wf/issue-110157.stderr
index e750ea47d515c..eb496628c5e0f 100644
--- a/tests/ui/wf/issue-110157.stderr
+++ b/tests/ui/wf/issue-110157.stderr
@@ -1,10 +1,10 @@
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/issue-110157.rs:6:12
    |
 LL |     F: Fn(&Missing) -> Result<I, ()>,
    |            ^^^^^^^ not found in this scope
 
-error[E0412]: cannot find type `Missing` in this scope
+error[E0425]: cannot find type `Missing` in this scope
   --> $DIR/issue-110157.rs:8:24
    |
 LL |     I: Iterator<Item = Missing>,
@@ -26,5 +26,5 @@ LL | |     I: Iterator<Item = Missing>,
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0046, E0412.
+Some errors have detailed explanations: E0046, E0425.
 For more information about an error, try `rustc --explain E0046`.
diff --git a/tests/ui/where-clauses/ignore-err-clauses.stderr b/tests/ui/where-clauses/ignore-err-clauses.stderr
index 9c76c1c6a0486..222b162cd482c 100644
--- a/tests/ui/where-clauses/ignore-err-clauses.stderr
+++ b/tests/ui/where-clauses/ignore-err-clauses.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `UUU` in this scope
+error[E0425]: cannot find type `UUU` in this scope
   --> $DIR/ignore-err-clauses.rs:6:5
    |
 LL |     UUU: Copy,
@@ -29,5 +29,5 @@ note: calling this operator moves the left-hand side
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0382, E0412.
+Some errors have detailed explanations: E0382, E0425.
 For more information about an error, try `rustc --explain E0382`.
diff --git a/tests/ui/where-clauses/normalization-of-unknown-type.stderr b/tests/ui/where-clauses/normalization-of-unknown-type.stderr
index 11b83224352b8..100d28ed2debe 100644
--- a/tests/ui/where-clauses/normalization-of-unknown-type.stderr
+++ b/tests/ui/where-clauses/normalization-of-unknown-type.stderr
@@ -1,4 +1,4 @@
-error[E0412]: cannot find type `Foo` in this scope
+error[E0425]: cannot find type `Foo` in this scope
   --> $DIR/normalization-of-unknown-type.rs:24:5
    |
 LL |     Foo: Filter,
@@ -6,4 +6,4 @@ LL |     Foo: Filter,
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0412`.
+For more information about this error, try `rustc --explain E0425`.