Run TLS destructors for wasm32-wasip1-threads

[surban]

The target wasm32-wasip1-threads has support for pthreads and allows registration of TLS destructors.

For spawned threads, this registers Rust TLS destructors by creating a pthreads key with an attached destructor function.
For the main thread, this registers an atexit handler to run the TLS destructors.

try-job: test-various

[rustbot]

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[surban]

As suggested I have switched to using the UNIX thread_local implementation for WASI.

For now I have added the missing libc declarations locally.
What is the way forward here? Shall I open a PR with the missing functions against the libc crate and then update the libc version of std?

[surban]

Note that the new implementation shows the behavior described in #28129.

However, this is consistent with the behavior of other UNIX platforms. I tested on FreeBSD and there TLS destructors are also not run for the main thread.

[surban]

I have created follow-up PR #133819 that deals with calling TLS destructors when the main thread exits on UNIX platforms other than Linux.

[jhpratt]

r? @joboet

You seem to have more knowledge of how this works, so feel free to take it over. I don't see anything wrong with the PR, though.

[joboet]

As suggested I have switched to using the UNIX thread_local implementation for WASI.

Great, thanks!

For now I have added the missing libc declarations locally.
What is the way forward here? Shall I open a PR with the missing functions against the libc crate and then update the libc version of std?

I'm totally OK with temporarily adding these here. A PR on libc would be appreciated though!

Note that the new implementation shows the behavior described in #28129.

However, this is consistent with the behavior of other UNIX platforms. I tested on FreeBSD and there TLS destructors are also not run for the main thread.

Considering that this is documented as a caveat, I think this is fine for now, especially since this PR is already a big improvement over the status quo.

I have created follow-up PR #133819 that deals with calling TLS destructors when the main thread exits on UNIX platforms other than Linux.

Cool, I'll have a look soon!

@bors r+

[bors]

📌 Commit 4fe15b0 has been approved by joboet

It is now in the queue for this repository.

[jieyouxu]

I believe this failed in rollup:

  error[E0432]: unresolved import `crate::sys::thread_local::destructors`
    --> library/std/src/sys/thread_local/guard/key.rs:10:9
     |
  10 |     use crate::sys::thread_local::destructors;
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `destructors` in `sys::thread_local`
     |
  note: found an item that was configured out
    --> library/std/src/sys/thread_local/mod.rs:54:16
     |
  54 | pub(crate) mod destructors {
     |                ^^^^^^^^^^^
  note: the item is gated here
    --> library/std/src/sys/thread_local/mod.rs:53:1
     |
  53 | #[cfg(all(target_thread_local, not(all(target_family = "wasm", not(target_feature = "atomics")))))]
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Included the test-various try job in case anyone wants to run it, which would exercise this test.

@bors r-

[surban]

This was caused by not distinguishing between wasm32-wasip1 and wasm32-wasip1-threads.

Should be fixed now.

[surban]

@rustbot review

[joboet]

@bors r+

[bors]

📌 Commit 4f16640 has been approved by joboet

It is now in the queue for this repository.

[Brooooooklyn]

When users compile to wasm32-wasip1-threads, they don't necessarily enable target_feature = "atomics", but the rust-std of wasm32-wasip1-threads always enables atomics, which causes some issues: #137510.

[Noratrieb]

Move this to #137510 (comment)