Rollup of 5 pull requests

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 {

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));
@@ -4363,15 +4363,15 @@ 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
                 // latter one - for paths in expression-position.
                 //
                 // 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.

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,

library/core/src/array/mod.rs

@@ -924,7 +924,7 @@ const fn try_from_fn_erased<R: [const] Try<Output: [const] Destruct>>(
 /// 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.
@@ -943,7 +943,7 @@ impl<T> Guard<'_, T> {
     #[rustc_const_unstable(feature = "array_try_from_fn", issue = "89379")]
     pub(crate) const 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);
@@ -972,7 +972,7 @@ impl<T: [const] Destruct> const 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`].
@@ -1004,6 +1004,7 @@ 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 {

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);
 

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")]