Rollup of 23 pull requests

[GuillaumeGomez]

Successful merges:

• bootstrap: forward -fdebug-prefix-map when using cc #159673 (bootstrap: forward -fdebug-prefix-map when using cc)
• document #[global_allocator] constraints #159720 (document #[global_allocator] constraints)
• optimization: don't look for diagnostic/canonical items without rustc_attrs enabled #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled)
• implement CovariantUnsafeCell #159738 (implement CovariantUnsafeCell)
• reuse regular exported_non_generic_symbols logic in Miri #159740 (reuse regular exported_non_generic_symbols logic in Miri)
• check extern "custom" function pointers #159780 (check extern "custom" function pointers)
• rustdoc-js: ignore editor temp files in test folder discovery #159786 (rustdoc-js: ignore editor temp files in test folder discovery)
• std::sync::poison: disable auto_cfg on PoisonError::new #159819 (std::sync::poison: disable auto_cfg on PoisonError::new)
• stepping into where-clauses during normalization may be productive #155388 (stepping into where-clauses during normalization may be productive)
• when bailing on ambiguity, don't force other results to ambig #155914 (when bailing on ambiguity, don't force other results to ambig)
• Add support to caller_location to rustc_public #159204 (Add support to caller_location to rustc_public)
• [rustdoc] Correctly handle output options with --show-coverage #159411 ([rustdoc] Correctly handle output options with --show-coverage)
• Fix(lib/fs/win): Fall back on Win32 delete for Dir::remove_file #159439 (Fix(lib/fs/win): Fall back on Win32 delete for Dir::remove_file)
• Update wasm-component-ld to 0.5.27 #159676 (Update wasm-component-ld to 0.5.27)
• allow accessing the contents of UnsafeCell without going through get #159730 (allow accessing the contents of UnsafeCell without going through get)
• Avoid #[target_features] #159809 (Avoid #[target_features])
• Add tuple never coercion collection regression test #159810 (Add tuple never coercion collection regression test)
• Remove redundant #[rustc_paren_sugar] feature gate #159826 (Remove redundant #[rustc_paren_sugar] feature gate)
• Updated expect messages for CString struct and method documentation #159853 (Updated expect messages for CString struct and method documentation)
• bootstrap: Remove obsolete option build.compiletest-use-stage0-libtest #159878 (bootstrap: Remove obsolete option build.compiletest-use-stage0-libtest)
• Update expect messages in library/alloc/boxed.rs and library/alloc/string.rs to follow the style guide #159882 (Update expect messages in library/alloc/boxed.rs and library/alloc/string.rs to follow the style guide)
• Split multiline derives into std/rustc macros #159891 (Split multiline derives into std/rustc macros)
• rustc-dev-guide subtree update #159895 (rustc-dev-guide subtree update)

r? @ghost

Create a similar rollup

[GuillaumeGomez]

@bors r+ p=5 rollup=never

[rust-bors]

📌 Commit 3a6add9 has been approved by GuillaumeGomez

It is now in the queue for this repository.

[rust-bors]

💔 Test for 0725aa3 failed: CI. Failed job:

• auto - aarch64-msvc-1 (web logs, enhanced plaintext logs)

[JonathanBrouwer]

@bors treeclosed=1000 spurious failures

[rust-bors]

Tree closed for PRs with priority less than 1000.

[rust-bors]

PR #159411, which is a member of this rollup, was unapproved.

[rust-log-analyzer]

The job aarch64-msvc-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [run-make] tests\run-make\rustdoc-show-coverage stdout ----

error: rmake recipe failed to complete
status: exit code: 101
command: "C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\test\\run-make\\rustdoc-show-coverage\\rmake.exe"
stdout: none
--- stderr -------------------------------
"C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\stage2\\bin\\rustdoc.exe" "foo.rs" "-Zunstable-options" "--show-coverage" "--target=aarch64-pc-windows-msvc"
output status: `exit code: 0`
=== STDOUT ===
+-------------------------------------+------------+------------+------------+------------+
| File                                | Documented | Percentage |   Examples | Percentage |
+-------------------------------------+------------+------------+------------+------------+
| foo.rs                              |          0 |       0.0% |          0 |       0.0% |
+-------------------------------------+------------+------------+------------+------------+
| Total                               |          0 |       0.0% |          0 |       0.0% |
+-------------------------------------+------------+------------+------------+------------+



=== STDERR ===



"C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\stage2\\bin\\rustdoc.exe" "foo.rs" "-Zunstable-options" "--show-coverage" "-o" "-" "--target=aarch64-pc-windows-msvc"
output status: `exit code: 0`
=== STDOUT ===
+-------------------------------------+------------+------------+------------+------------+
| File                                | Documented | Percentage |   Examples | Percentage |
+-------------------------------------+------------+------------+------------+------------+
| foo.rs                              |          0 |       0.0% |          0 |       0.0% |
+-------------------------------------+------------+------------+------------+------------+
| Total                               |          0 |       0.0% |          0 |       0.0% |
+-------------------------------------+------------+------------+------------+------------+



=== STDERR ===



"C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\stage2\\bin\\rustdoc.exe" "foo.rs" "-Zunstable-options" "--show-coverage" "--output-format=json" "--target=aarch64-pc-windows-msvc"
output status: `exit code: 0`
=== STDOUT ===
{"foo.rs":{"total":3,"with_docs":0,"total_examples":2,"with_examples":0}}



=== STDERR ===



"C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\stage2\\bin\\rustdoc.exe" "foo.rs" "-Zunstable-options" "--show-coverage" "--output-format=json" "-o" "-" "--target=aarch64-pc-windows-msvc"
output status: `exit code: 0`
=== STDOUT ===
{"foo.rs":{"total":3,"with_docs":0,"total_examples":2,"with_examples":0}}



=== STDERR ===

---



assert_contains_regex:
=== HAYSTACK ===
Generated output into "doc\\foo.txt"

=== NEEDLE ===
Generated output into "doc[/\\]foo.txt"


thread 'main' (9516) panicked at C:\a\rust\rust\tests\run-make\rustdoc-show-coverage\rmake.rs:40:5:
regex was not found in haystack
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
---
Currently active steps:
test::RunMake { test_compiler: Compiler { stage: 2, host: aarch64-pc-windows-msvc, forced_compiler: false }, target: aarch64-pc-windows-msvc } at src\bootstrap\src\core\build_steps\test.rs:1959
test::Compiletest { test_compiler: Compiler { stage: 2, host: aarch64-pc-windows-msvc, forced_compiler: false }, target: aarch64-pc-windows-msvc, mode: run-make, suite: "run-make", path: "tests/run-make", compare_mode: None } at src\bootstrap\src\core\build_steps\test.rs:1959
Build completed unsuccessfully in 1:51:48
make: *** [Makefile:115: ci-msvc-py] Error 1
  local time: Sat Jul 25 16:32:59 CUT 2026
  network time: Sat, 25 Jul 2026 16:32:59 GMT
##[error]Process completed with exit code 2.
##[group]Run echo "disk usage:"
echo "disk usage:"