Auto merge of rust-lang#81240 - JohnTitor:rollup-ieaz82a, r=JohnTitor

Rollup of 11 pull requests

Successful merges:

 - rust-lang#79655 (Add Vec visualization to understand capacity)
 - rust-lang#80172 (Use consistent punctuation for 'Prelude contents' docs)
 - rust-lang#80429 (Add regression test for mutual recursion in obligation forest)
 - rust-lang#80601 (Improve grammar in documentation of format strings)
 - rust-lang#81046 (Improve unknown external crate error)
 - rust-lang#81178 (Visit only terminators when removing landing pads)
 - rust-lang#81179 (Fix broken links with `--document-private-items` in the standard library)
 - rust-lang#81184 (Remove unnecessary `after_run` function)
 - rust-lang#81185 (Fix ICE in mir when evaluating SizeOf on unsized type)
 - rust-lang#81187 (Fix typo in counters.rs)
 - rust-lang#81219 (Document security implications of std::env::temp_dir)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

alloc/src/fmt.rs

@@ -282,21 +282,22 @@
 //! `%`. The actual grammar for the formatting syntax is:
 //!
 //! ```text
-//! format_string := <text> [ maybe-format <text> ] *
-//! maybe-format := '{' '{' | '}' '}' | <format>
+//! format_string := text [ maybe_format text ] *
+//! maybe_format := '{' '{' | '}' '}' | format
 //! format := '{' [ argument ] [ ':' format_spec ] '}'
 //! argument := integer | identifier
 //!
-//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision][type]
+//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision]type
 //! fill := character
 //! align := '<' | '^' | '>'
 //! sign := '+' | '-'
 //! width := count
 //! precision := count | '*'
-//! type := identifier | '?' | ''
+//! type := '' | '?' | 'x?' | 'X?' | identifier
 //! count := parameter | integer
 //! parameter := argument '$'
 //! ```
+//! In the above grammar, `text` may not contain any `'{'` or `'}'` characters.
 //!
 //! # Formatting traits
 //!

alloc/src/vec/mod.rs

@@ -285,6 +285,27 @@ mod spec_extend;
 /// you would see if you coerced it to a slice), followed by [`capacity`]` -
 /// `[`len`] logically uninitialized, contiguous elements.
 ///
+/// A vector containing the elements `'a'` and `'b'` with capacity 4 can be
+/// visualized as below. The top part is the `Vec` struct, it contains a
+/// pointer to the head of the allocation in the heap, length and capacity.
+/// The bottom part is the allocation on the heap, a contiguous memory block.
+///
+/// ```text
+///             ptr      len  capacity
+///        +--------+--------+--------+
+///        | 0x0123 |      2 |      4 |
+///        +--------+--------+--------+
+///             |
+///             v
+/// Heap   +--------+--------+--------+--------+
+///        |    'a' |    'b' | uninit | uninit |
+///        +--------+--------+--------+--------+
+/// ```
+///
+/// - **uninit** represents memory that is not initialized, see [`MaybeUninit`].
+/// - Note: the ABI is not stable and `Vec` makes no guarantees about its memory
+///   layout (including the order of fields).
+///
 /// `Vec` will never perform a "small optimization" where elements are actually
 /// stored on the stack for two reasons:
 ///
@@ -345,6 +366,7 @@ mod spec_extend;
 /// [`push`]: Vec::push
 /// [`insert`]: Vec::insert
 /// [`reserve`]: Vec::reserve
+/// [`MaybeUninit`]: core::mem::MaybeUninit
 /// [owned slice]: Box
 /// [slice]: ../../std/primitive.slice.html
 /// [`&`]: ../../std/primitive.reference.html

alloc/src/vec/spec_from_iter_nested.rs

@@ -5,7 +5,7 @@ use super::{SpecExtend, Vec};
 
 /// Another specialization trait for Vec::from_iter
 /// necessary to manually prioritize overlapping specializations
-/// see [`SpecFromIter`] for details.
+/// see [`SpecFromIter`](super::SpecFromIter) for details.
 pub(super) trait SpecFromIterNested<T, I> {
     fn from_iter(iter: I) -> Self;
 }

std/src/env.rs

@@ -561,6 +561,13 @@ pub fn home_dir() -> Option<PathBuf> {
 
 /// Returns the path of a temporary directory.
 ///
+/// The temporary directory may be shared among users, or between processes
+/// with different privileges; thus, the creation of any files or directories
+/// in the temporary directory must use a secure method to create a uniquely
+/// named file. Creating a file or directory with a fixed or predictable name
+/// may result in "insecure temporary file" security vulnerabilities. Consider
+/// using a crate that securely creates temporary files or directories.
+///
 /// # Unix
 ///
 /// Returns the value of the `TMPDIR` environment variable if it is
@@ -580,14 +587,10 @@ pub fn home_dir() -> Option<PathBuf> {
 ///
 /// ```no_run
 /// use std::env;
-/// use std::fs::File;
 ///
-/// fn main() -> std::io::Result<()> {
+/// fn main() {
 ///     let mut dir = env::temp_dir();
-///     dir.push("foo.txt");
-///
-///     let f = File::create(dir)?;
-///     Ok(())
+///     println!("Temporary directory: {}", dir.display());
 /// }
 /// ```
 #[stable(feature = "env", since = "1.0.0")]

std/src/io/prelude.rs

@@ -1,4 +1,4 @@
-//! The I/O Prelude
+//! The I/O Prelude.
 //!
 //! The purpose of this module is to alleviate imports of many common I/O traits
 //! by adding a glob import to the top of I/O heavy modules:

std/src/prelude/mod.rs

@@ -1,4 +1,4 @@
-//! The Rust Prelude.
+//! # The Rust Prelude
 //!
 //! Rust comes with a variety of things in its standard library. However, if
 //! you had to manually import every single thing that you used, it would be
@@ -28,35 +28,35 @@
 //! The current version of the prelude (version 1) lives in
 //! [`std::prelude::v1`], and re-exports the following:
 //!
-//! * [`std::marker`]::{[`Copy`], [`Send`], [`Sized`], [`Sync`], [`Unpin`]},
+//! * [`std::marker`]::{[`Copy`], [`Send`], [`Sized`], [`Sync`], [`Unpin`]}:
 //!   marker traits that indicate fundamental properties of types.
-//! * [`std::ops`]::{[`Drop`], [`Fn`], [`FnMut`], [`FnOnce`]}, various
+//! * [`std::ops`]::{[`Drop`], [`Fn`], [`FnMut`], [`FnOnce`]}: various
 //!   operations for both destructors and overloading `()`.
-//! * [`std::mem`]::[`drop`][`mem::drop`], a convenience function for explicitly
+//! * [`std::mem`]::[`drop`][`mem::drop`]: a convenience function for explicitly
 //!   dropping a value.
-//! * [`std::boxed`]::[`Box`], a way to allocate values on the heap.
-//! * [`std::borrow`]::[`ToOwned`], the conversion trait that defines
+//! * [`std::boxed`]::[`Box`]: a way to allocate values on the heap.
+//! * [`std::borrow`]::[`ToOwned`]: the conversion trait that defines
 //!   [`to_owned`], the generic method for creating an owned type from a
 //!   borrowed type.
-//! * [`std::clone`]::[`Clone`], the ubiquitous trait that defines
+//! * [`std::clone`]::[`Clone`]: the ubiquitous trait that defines
 //!   [`clone`][`Clone::clone`], the method for producing a copy of a value.
-//! * [`std::cmp`]::{[`PartialEq`], [`PartialOrd`], [`Eq`], [`Ord`] }, the
+//! * [`std::cmp`]::{[`PartialEq`], [`PartialOrd`], [`Eq`], [`Ord`]}: the
 //!   comparison traits, which implement the comparison operators and are often
 //!   seen in trait bounds.
-//! * [`std::convert`]::{[`AsRef`], [`AsMut`], [`Into`], [`From`]}, generic
+//! * [`std::convert`]::{[`AsRef`], [`AsMut`], [`Into`], [`From`]}: generic
 //!   conversions, used by savvy API authors to create overloaded methods.
 //! * [`std::default`]::[`Default`], types that have default values.
-//! * [`std::iter`]::{[`Iterator`], [`Extend`], [`IntoIterator`]
-//!   [`DoubleEndedIterator`], [`ExactSizeIterator`]}, iterators of various
+//! * [`std::iter`]::{[`Iterator`], [`Extend`], [`IntoIterator`],
+//!   [`DoubleEndedIterator`], [`ExactSizeIterator`]}: iterators of various
 //!   kinds.
 //! * [`std::option`]::[`Option`]::{[`self`][`Option`], [`Some`], [`None`]}, a
 //!   type which expresses the presence or absence of a value. This type is so
 //!   commonly used, its variants are also exported.
-//! * [`std::result`]::[`Result`]::{[`self`][`Result`], [`Ok`], [`Err`]}, a type
+//! * [`std::result`]::[`Result`]::{[`self`][`Result`], [`Ok`], [`Err`]}: a type
 //!   for functions that may succeed or fail. Like [`Option`], its variants are
 //!   exported as well.
-//! * [`std::string`]::{[`String`], [`ToString`]}, heap allocated strings.
-//! * [`std::vec`]::[`Vec`], a growable, heap-allocated vector.
+//! * [`std::string`]::{[`String`], [`ToString`]}: heap-allocated strings.
+//! * [`std::vec`]::[`Vec`]: a growable, heap-allocated vector.
 //!
 //! [`mem::drop`]: crate::mem::drop
 //! [`std::borrow`]: crate::borrow