Documented thread hooks on panics and errors of thread spawning functions. by AhoyISki · Pull Request #149927 · rust-lang/rust

AhoyISki · 2025-12-12T19:16:28Z

This PR solves a concern regarding #132951

Considering that the feature has been on nightly for over a year, I would also like to see it stabilized, since no one has voiced any concerns about its current implementation.

… spawning functions.

rustbot · 2025-12-12T19:16:32Z

r? @joboet

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joboet · 2025-12-12T20:44:43Z

library/std/src/thread/builder.rs

    ///
    /// Panics if a thread name was set and it contained null bytes.
    ///
+    /// Unlike the [`spawn`] free function, if it panics for this reason, the


Unlike the spawn free function

thread::spawn calls Builder::spawn internally, so this is misleading – it's just that thread::spawn doesn't set a thread name and thus will never panic for this reason.

Ok, I will rephrase.

joboet · 2025-12-12T20:47:19Z

library/std/src/thread/functions.rs

+/// Panics if the OS fails to create a thread; use [`Builder::spawn`] to recover
+/// from such errors.
+///
+/// Additionally, if hooks were added via [`add_spawn_hook`], they will still be


"Additionally" isn't a good phrasing here, this isn't describing another panicking case, but rather adding more detail to the previous sentence. How about just combining the two paragraphs without any conjunction? Like

Panics if the OS fails to create a thread; use Builder::spawn to recover from such errors. If hooks...

joboet · 2025-12-12T20:51:54Z

library/std/src/thread/scoped.rs

    /// Panics if the OS fails to create a thread; use [`Builder::spawn_scoped`]
    /// to recover from such errors.
    ///
+    /// like the free [`spawn`] function, if hooks were added via [`add_spawn_hook`],


This should then match the thread::spawn documentation exactly.

joboet · 2025-12-12T20:53:17Z

library/std/src/thread/scoped.rs

    /// Panics if a thread name was set and it contained null bytes.
    ///
+    /// Unlike with [`Scope::spawn`], if it panics for this reason, the hooks
+    /// added by [`add_spawn_hook`] will _not_ be called.


The same nit applies here.

rustbot · 2025-12-12T20:53:31Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Reword documentation for clarity regarding spawn hooks.

Removed unused documentation reference to `spawn` in scoped thread.

AhoyISki · 2025-12-13T00:01:21Z

@rustbot ready

joboet · 2025-12-16T06:23:50Z

r? libs-api
This is just documenting the current behaviour, but I'd appreciate a signoff anyway.

bors · 2026-01-01T09:14:09Z

☔ The latest upstream changes (presumably #150559) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2026-01-11T22:17:51Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

rustbot · 2026-01-11T22:17:52Z

⚠️ Warning ⚠️

The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.
- 4e79475
You can start a rebase with the following commands:
```
$ # rebase
$ git pull --rebase https://github.com/rust-lang/rust.git main
$ git push --force-with-lease
```

rust-log-analyzer · 2026-01-11T23:20:59Z

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain enhanced) (plain)

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

............................................       (144/144)

======== tests/rustdoc-gui/notable-trait.goml ========

[ERROR] line 255: expected 0 elements, found 1: for command `assert-count: ("//*[@class='tooltip popover']", 0)`
    at <file:///checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/doc/test_docs/struct.NotableStructWithLongName.html#method.create_an_iterator_from_read>

======== tests/rustdoc-gui/search-result-display.goml ========

[WARNING] line 39: Delta is 0 for "x", maybe try to use `compare-elements-position` instead?

BrynCooke · 2026-01-27T14:29:48Z

@AhoyISki I would love to see the thread hooks feature stabilized. Does this need rebasing by by you before this can move forward?

AhoyISki · 2026-01-27T15:07:12Z

@BrynCooke I guess I need to do the steps above, huh? I'll try to do that later today

Added documentation about thread hooks to panics and errors in thread…

d3e4f2b

… spawning functions.

rustbot assigned joboet Dec 12, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 12, 2025

joboet requested changes Dec 12, 2025

View reviewed changes

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 12, 2025

AhoyISki added 4 commits December 12, 2025 19:25

Documentation rephrasing

a7185e9

Documentation rephrasing

8f0a1ce

Documentation rephrasing

d3a7384

Reword documentation for clarity regarding spawn hooks.

Remove unused spawn reference in scoped.rs

9a7daa3

Removed unused documentation reference to `spawn` in scoped thread.

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 13, 2025

AhoyISki requested a review from joboet December 13, 2025 02:02

joboet approved these changes Dec 16, 2025

View reviewed changes

rustbot added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Dec 16, 2025

rustbot assigned the8472 and unassigned joboet Dec 16, 2025

Merge branch 'main' into main

4e79475

rustbot added has-merge-commits PR has merge commits, merge with caution. S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 11, 2026

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AhoyISki commented Dec 12, 2025 •

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