Auto merge of #83301 - Dylan-DPC:rollup-x1yzvhm, r=Dylan-DPC

Rollup of 11 pull requests

Successful merges:

 - #82500 (Reuse `std::sys::unsupported::pipe` on `hermit`)
 - #82759 (Remove unwrap_none/expect_none from compiler/.)
 - #82846 (rustdoc: allow list syntax for #[doc(alias)] attributes)
 - #82892 (Clarify docs for Read::read's return value)
 - #83179 (Extend `proc_macro_back_compat` lint to `actix-web`)
 - #83197 (Move some test-only code to test files)
 - #83208 (Fix gitattibutes for old git versions)
 - #83215 (Deprecate std::os::haiku::raw, which accidentally wasn't deprecated)
 - #83230 (Remove unnecessary `forward_inner_docs` hack)
 - #83236 (Upgrade memmap to memmap2)
 - #83270 (Fix typo/inaccuracy in the documentation of Iterator::skip_while)

Failed merges:

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

1 files changed, 7 insertions, 2 deletions

diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index 17002e3b860..6abb300054a 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -514,8 +514,8 @@ pub trait Read {
     /// waiting for data, but if an object needs to block for a read and cannot,
     /// it will typically signal this via an [`Err`] return value.
     ///
-    /// If the return value of this method is [`Ok(n)`], then it must be
-    /// guaranteed that `0 <= n <= buf.len()`. A nonzero `n` value indicates
+    /// If the return value of this method is [`Ok(n)`], then implementations must
+    /// guarantee that `0 <= n <= buf.len()`. A nonzero `n` value indicates
     /// that the buffer `buf` has been filled in with `n` bytes of data from this
     /// source. If `n` is `0`, then it can indicate one of two scenarios:
     ///
@@ -529,6 +529,11 @@ pub trait Read {
     /// This may happen for example because fewer bytes are actually available right now
     /// (e. g. being close to end-of-file) or because read() was interrupted by a signal.
     ///
+    /// As this trait is safe to implement, callers cannot rely on `n <= buf.len()` for safety.
+    /// Extra care needs to be taken when `unsafe` functions are used to access the read bytes.
+    /// Callers have to ensure that no unchecked out-of-bounds accesses are possible even if
+    /// `n > buf.len()`.
+    ///
     /// No guarantees are provided about the contents of `buf` when this
     /// function is called, implementations cannot rely on any property of the
     /// contents of `buf` being true. It is recommended that *implementations*