Auto merge of #124015 - GuillaumeGomez:rollup-s46ksxa, r=GuillaumeGomez

Rollup of 14 pull requests

Successful merges:

 - #120781 (Correct usage note on OpenOptions::append())
 - #121694 (sess: stabilize `-Zrelro-level` as `-Crelro-level`)
 - #122521 (doc(bootstrap): add top-level doc-comment to utils/tarball.rs)
 - #123491 (Fix ICE in `eval_body_using_ecx`)
 - #123574 (rustdoc: rename `issue-\d+.rs` tests to have meaningful names (part 6))
 - #123687 (Update ar_archive_writer to 0.2.0)
 - #123721 (Various visionOS fixes)
 - #123797 (Better graphviz output for SCCs and NLL constraints)
 - #123990 (Make `suggest_deref_closure_return` more idiomatic/easier to understand)
 - #123995 (Make `thir_tree` and `thir_flat` into hooks)
 - #123998 (Opaque types have no namespace)
 - #124001 (Fix docs for unstable_features lint.)
 - #124006 (Move size assertions for `mir::syntax` types into the same file)
 - #124011 (rustdoc: update the module-level docs of `rustdoc::clean`)

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

2 files changed, 19 insertions, 21 deletions

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index 8a24949631c..1293abddaf3 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -980,15 +980,21 @@ impl OpenOptions {
     /// Note that setting `.write(true).append(true)` has the same effect as
     /// setting only `.append(true)`.
     ///
-    /// For most filesystems, the operating system guarantees that all writes are
-    /// atomic: no writes get mangled because another process writes at the same
-    /// time.
-    ///
-    /// One maybe obvious note when using append-mode: make sure that all data
-    /// that belongs together is written to the file in one operation. This
-    /// can be done by concatenating strings before passing them to [`write()`],
-    /// or using a buffered writer (with a buffer of adequate size),
-    /// and calling [`flush()`] when the message is complete.
+    /// Append mode guarantees that writes will be positioned at the current end of file,
+    /// even when there are other processes or threads appending to the same file. This is
+    /// unlike <code>[seek]\([SeekFrom]::[End]\(0))</code> followed by `write()`, which
+    /// has a race between seeking and writing during which another writer can write, with
+    /// our `write()` overwriting their data.
+    ///
+    /// Keep in mind that this does not necessarily guarantee that data appended by
+    /// different processes or threads does not interleave. The amount of data accepted a
+    /// single `write()` call depends on the operating system and file system. A
+    /// successful `write()` is allowed to write only part of the given data, so even if
+    /// you're careful to provide the whole message in a single call to `write()`, there
+    /// is no guarantee that it will be written out in full. If you rely on the filesystem
+    /// accepting the message in a single write, make sure that all data that belongs
+    /// together is written in one operation. This can be done by concatenating strings
+    /// before passing them to [`write()`].
     ///
     /// If a file is opened with both read and append access, beware that after
     /// opening, and after every write, the position for reading may be set at the
@@ -1003,6 +1009,9 @@ impl OpenOptions {
     /// [`write()`]: Write::write "io::Write::write"
     /// [`flush()`]: Write::flush "io::Write::flush"
     /// [stream_position]: Seek::stream_position "io::Seek::stream_position"
+    /// [seek]: Seek::seek "io::Seek::seek"
+    /// [Current]: SeekFrom::Current "io::SeekFrom::Current"
+    /// [End]: SeekFrom::End "io::SeekFrom::End"
     ///
     /// # Examples
     ///
diff --git a/library/std/src/sys/pal/unix/process/process_unix.rs b/library/std/src/sys/pal/unix/process/process_unix.rs
index e798510f9e6..d65657790c4 100644
--- a/library/std/src/sys/pal/unix/process/process_unix.rs
+++ b/library/std/src/sys/pal/unix/process/process_unix.rs
@@ -11,18 +11,6 @@ use crate::os::linux::process::PidFd;
 #[cfg(target_os = "linux")]
 use crate::os::unix::io::AsRawFd;
 
-#[cfg(any(
-    target_os = "macos",
-    target_os = "watchos",
-    target_os = "visionos",
-    target_os = "tvos",
-    target_os = "freebsd",
-    all(target_os = "linux", target_env = "gnu"),
-    all(target_os = "linux", target_env = "musl"),
-    target_os = "nto",
-))]
-use crate::sys::weak::weak;
-
 #[cfg(target_os = "vxworks")]
 use libc::RTP_ID as pid_t;
 
@@ -466,6 +454,7 @@ impl Command {
         envp: Option<&CStringArray>,
     ) -> io::Result<Option<Process>> {
         use crate::mem::MaybeUninit;
+        use crate::sys::weak::weak;
         use crate::sys::{self, cvt_nz, unix_sigpipe_attr_specified};
 
         if self.get_gid().is_some()