New tier-2 target for `wasm32-wasi` + threads #574

abrown · 2022-12-21T18:14:54Z

Proposal

Several of us working on WebAssembly (cc: @alexcrichton, @loganek, @sunfishcode, @sbc100, @AlexEne) have made progress on a WASI proposal to allow spawning threads in WebAssembly programs via a new WASI interface: wasi-threads. Several issues related to the proposal are still under discussion, but the core idea is implemented in at least two WebAssembly engines (Wasmtime and WAMR) and a subset of the pthreads API is supported for the C language via wasi-libc. I am opening this issue to request adding support for this in the Rust compiler.

Why a new target? wasi-threads relies on the WebAssembly threads proposal; modules built with threads enabled allow new features such as atomic instructions and shared memories. Not all users will want to allow threads-enabled programs in their environment but still will want to compile to wasm32-wasi: after some discussion here, we decided to use a new target triple to indicate that a program targets both WASI (including wasi-threads) and the WebAssembly threads feature.

In wasi-libc, this target is currently named wasm32-wasi-pthread but this name has not yet been released and could change. I would prefer, for simplicity, that the wasi-libc target and the rustc target were the same, so I can change the wasi-libc one if there are other suggestions here (e.g., wasm32-wasi-threads?). Let the bikeshedding begin...

What is more important is whether to approve this proposal: can we add a new target (very similar to wasm32-wasi) that allows us to implement wasi-threads in Rust? Some previous work on this includes getting the atomics build to work; eventually this looks like implementing Thread::spawn via wasi_thread_spawn. The new target gives us the ability to incrementally fill in the implementation details as wasi-libc and the wasi-threads proposal evolve.

Mentors or Reviewers

@alexcrichton

Process

The main points of the Major Change Process are as follows:

File an issue describing the proposal.
A compiler team member or contributor who is knowledgeable in the area can second by writing @rustbot second.
- Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a -C flag, then full team check-off is required.
- Compiler team members can initiate a check-off via @rfcbot fcp merge on either the MCP or the PR.
Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.

You can read more about Major Change Proposals on forge.

Comments

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

The text was updated successfully, but these errors were encountered:

rustbot · 2022-12-21T18:14:56Z

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

cc @rust-lang/compiler @rust-lang/compiler-contributors

nagisa · 2023-01-11T18:33:23Z

@rustbot second

I think it makes sense to add a target in this particular instance. Though, as I mentioned in the Zulip thread, I’m not sure what the most appropriate name for such a target would be, or how to steer code to continue using target_ CFGs to decide on specific behaviours and implementations rather than the target name verbatim.

After some thought, I think that we should rename the `THREAD_MODEL=posix` build to avoid confusion. Why? Though in this project the use of this target does involve pthreads, it will not be so in other standard libraries or languages (see, e.g., rust-lang/compiler-team#574). I think it would be preferable to emphasize the "threads" Wasm-level proposal and the "wasi-threads" proposal rather than the specific details of which threading API is being exposed.

* Change `wasm32-wasi-pthread` to `wasm32-wasi-threads` After some thought, I think that we should rename the `THREAD_MODEL=posix` build to avoid confusion. Why? Though in this project the use of this target does involve pthreads, it will not be so in other standard libraries or languages (see, e.g., rust-lang/compiler-team#574). I think it would be preferable to emphasize the "threads" Wasm-level proposal and the "wasi-threads" proposal rather than the specific details of which threading API is being exposed. * fix: rename the `expected` output directory as well

apiraino · 2023-01-24T08:40:20Z

@rustbot label -final-comment-period +major-change-accepted

…sembly#381) * Change `wasm32-wasi-pthread` to `wasm32-wasi-threads` After some thought, I think that we should rename the `THREAD_MODEL=posix` build to avoid confusion. Why? Though in this project the use of this target does involve pthreads, it will not be so in other standard libraries or languages (see, e.g., rust-lang/compiler-team#574). I think it would be preferable to emphasize the "threads" Wasm-level proposal and the "wasi-threads" proposal rather than the specific details of which threading API is being exposed. * fix: rename the `expected` output directory as well

eloparco · 2023-03-21T11:12:57Z

While this proposal gets implemented, how can I use WASI threads in Rust? I have some rust code that uses pthreads, something like

extern "C" {
    fn pthread_create(
        thread: &mut pthread_t,
        attr: *const c_void,
        func: extern "C" fn(*const c_void) -> *mut c_void,
        arg: *const c_void,
    ) -> i32;
    fn pthread_mutex_init(mutex: pthread_mutex_t, attr: *mut c_void) -> i32;
}

but I don't understand how to tell cargo to use the wasi-sdk to compile. I was looking at this issue rust-lang/rust#76679 but it didn't work.

abrown · 2023-03-21T12:52:27Z

I don't think you can yet. I've been waiting for the LLVM 16 support to be incorporated into rustc and now that that has happened, I was planning to look at implementing the new wasm32-wasi-threads target and std::thread::spawn.

eloparco · 2023-03-21T13:52:34Z

So there's no way to use it right now, correct? Not even a hacky way.
I thought there was an option to tell cargo which compiler and linker to use (so that I could specify to use the one in wasi-sdk).

…wiser WASI threads, implementation of wasm32-wasi-preview1-threads target This PR adds a target proposed in rust-lang/compiler-team#574 by `@abrown` and implementation of `std::thread::spawn` for the target `wasm32-wasi-preview1-threads` ### Tier 3 Target Policy As tier 3 targets, the new targets are required to adhere to [the tier 3 target policy](https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html#tier-3-target-policy) requirements. This section quotes each requirement in entirety and describes how they are met. > - A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.) See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target. > - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it. If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo. The target is using the same name for $ARCH=wasm32 and $OS=wasi as existing Rust targets. The suffix `preview1` introduced to accurately set expectations because eventually this target will be deprecated and follows [MCP 607](rust-lang/compiler-team#607). The suffix `threads` indicates that it’s an extension that enables threads to the existing target and it follows [MCP 574](rust-lang/compiler-team#574) which describes the rationale behind introducing a separate target. > - Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users. > - The target must not introduce license incompatibilities. > - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0). > - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements. > - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3. > - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users. This PR does not introduce any new dependency. The new target doesn’t support building host tools. > Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions. The full standard library is available for this target as it’s an extension to an existing target that has already supported it. > The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary. Only manual test running is supported at the moment with some tweaks in the test runner codebase. For build and running tests see [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions. > - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements. > - Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages. > - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. > - Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target. > - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target. I acknowledge these requirements and intend to ensure they are met.

WASI threads, implementation of wasm32-wasi-preview1-threads target This PR adds a target proposed in rust-lang/compiler-team#574 by `@abrown` and implementation of `std::thread::spawn` for the target `wasm32-wasi-preview1-threads` ### Tier 3 Target Policy As tier 3 targets, the new targets are required to adhere to [the tier 3 target policy](https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html#tier-3-target-policy) requirements. This section quotes each requirement in entirety and describes how they are met. > - A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.) See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target. > - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it. If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo. The target is using the same name for $ARCH=wasm32 and $OS=wasi as existing Rust targets. The suffix `preview1` introduced to accurately set expectations because eventually this target will be deprecated and follows [MCP 607](rust-lang/compiler-team#607). The suffix `threads` indicates that it’s an extension that enables threads to the existing target and it follows [MCP 574](rust-lang/compiler-team#574) which describes the rationale behind introducing a separate target. > - Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users. > - The target must not introduce license incompatibilities. > - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0). > - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements. > - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3. > - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users. This PR does not introduce any new dependency. The new target doesn’t support building host tools. > Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions. The full standard library is available for this target as it’s an extension to an existing target that has already supported it. > The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary. Only manual test running is supported at the moment with some tweaks in the test runner codebase. For build and running tests see [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions. > - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements. > - Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages. > - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. > - Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target. > - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target. I acknowledge these requirements and intend to ensure they are met.

…r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by `@g0djan` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

…r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via ``@)`` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by ``@g0djan`` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

…r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via ```@)``` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by ```@g0djan``` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

…r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via ````@)```` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by ````@g0djan```` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

…r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via `````@)````` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by `````@g0djan````` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

Rollup merge of rust-lang#115345 - g0djan:godjan/tier2-wasi-threads, r=WaffleLapkin MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/compiler-team#661 >A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.) The feature is already implemented in [wasi-sdk(](https://github.com/WebAssembly/wasi-sdk) (C toolchain for WASM), and four different WASM runtimes([Wasmtime](https://github.com/bytecodealliance/wasmtime), [WAMR](https://github.com/bytecodealliance/wasm-micro-runtime), [Wasmer](https://github.com/wasmerio/wasmer), [toywasm](https://github.com/yamt/toywasm)) are compatible with it. >A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers. >The target maintainers should not only fix target-specific issues, but should use any such issue as an opportunity to educate the Rust community about portability to their target, and enhance documentation of the target. We already have a team of 4 developers. See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). The documentation is being updated in this PR as the first occurrence. >The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target. It doesn't as it’s built on top of existing wasm32-wasi tier-2 target and it only extends stdlib by implementing std:: thread::spawn/join. > The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent. For build and running tests see *Building Rust programs* and *Testing* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Only manual test running is supported at the moment with some tweaks in the test runner codebase. > The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar. See *Platform requirements* in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md) > If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target. >Note that in some cases, based on the usage of existing targets within the Rust community, Rust developers or a target's maintainers may wish to modify the baseline expectations of a target, or split an existing target into multiple targets with different baseline expectations. A proposal to do so will be treated similarly to the analogous promotion, demotion, or removal of a target, according to this policy, with the same team approvals required. >For instance, if an OS version has become obsolete and unsupported, a target for that OS may raise its baseline expectations for OS version (treated as though removing a target corresponding to the older versions), or a target for that OS may split out support for older OS versions into a lower-tier target (treated as though demoting a target corresponding to the older versions, and requiring justification for a new target at a lower tier for the older OS versions). Justified in rust-lang/compiler-team#574 and I acknowledge these requirements and intend to ensure they are met. > Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target. >The right approach to handling a missing feature from a target may depend on whether the target seems likely to develop the feature in the future. In some cases, a target may be co-developed along with Rust support, and Rust may gain new features on the target as that target gains the capabilities to support those features. >As an exception, a target identical to an existing tier 1 target except for lower baseline expectations for the OS, CPU, or similar, may propose to qualify as tier 2 (but not higher) without support for std if the target will primarily be used in no_std applications, to reduce the support burden for the standard library. In this case, evaluation of the proposed target's value will take this limitation into account. It does not, as it’s built as an extension of the existing tier 2 target (wasm32-wasi). > The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features. >For example, if Rust relies on a specific code generation feature to ensure that safe code cannot overflow the stack, the code generation for the target should support that feature. >If the Rust compiler introduces new safety properties (such as via new capabilities of a compiler backend), the Rust compiler team will determine if they consider those new safety properties a best-effort improvement for specific targets, or a required property for all Rust targets. In the latter case, the compiler team may require the maintainers of existing targets to either implement and confirm support for the property or update the target tier list with documentation of the missing property. Doesn't apply, the target re-uses existing backend and doesn't extend it > If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however. Target does not support C code >The target must build reliably in CI, for all components that Rust's CI considers mandatory. The target reliably builds in CI already https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/dist-various-2/Dockerfile#L143. >The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems. The existing tier-2 target and this target as its extension [pass](rust-lang#112922 (comment)) for 14.5k+ tests/ui when tests are run manually(described in *Testing* in in [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md). Can be tested in the CI as soon as the original target does. > Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account. It doesn’t as it only slightly extends standard library of the existing target > Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools. N/a given as it only extends stdlib of the existing target. > In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams. >As an exception to this, if the target's primary purpose is to build components for a Free and Open Source Software (FOSS) project licensed under "copyleft" terms (terms which require licensing other code under compatible FOSS terms), such as kernel modules or plugins, then the standard libraries for the target may potentially be subject to copyleft terms, as long as such terms are satisfied by Rust's existing practices of providing full corresponding source code. Note that anything added to the Rust repository itself must still use Rust's standard license terms. Requirement are met, no legal issues. > Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via `````@)````` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages. >Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. I acknowledge these requirements and intend to ensure they are met. > The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion. The tests are run manually every week by `````@g0djan````` now. While target has been in Tier 3, 2 issues(rust-lang#114608 and rust-lang#114610) have been raised. Both issues were addressed the same day and fixes has been merged by now. > All requirements for tier 3 apply. Target was initially accepted as a Tier 3 target in rust-lang#112922 .

WASI threads, implementation of wasm32-wasi-preview1-threads target This PR adds a target proposed in rust-lang/compiler-team#574 by `@abrown` and implementation of `std::thread::spawn` for the target `wasm32-wasi-preview1-threads` ### Tier 3 Target Policy As tier 3 targets, the new targets are required to adhere to [the tier 3 target policy](https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html#tier-3-target-policy) requirements. This section quotes each requirement in entirety and describes how they are met. > - A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.) See [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target. > - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it. If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo. The target is using the same name for $ARCH=wasm32 and $OS=wasi as existing Rust targets. The suffix `preview1` introduced to accurately set expectations because eventually this target will be deprecated and follows [MCP 607](rust-lang/compiler-team#607). The suffix `threads` indicates that it’s an extension that enables threads to the existing target and it follows [MCP 574](rust-lang/compiler-team#574) which describes the rationale behind introducing a separate target. > - Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users. > - The target must not introduce license incompatibilities. > - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0). > - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements. > - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3. > - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users. This PR does not introduce any new dependency. The new target doesn’t support building host tools. > Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions. The full standard library is available for this target as it’s an extension to an existing target that has already supported it. > The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary. Only manual test running is supported at the moment with some tweaks in the test runner codebase. For build and running tests see [src/doc/rustc/src/platform-support/wasm32-wasi-preview1-threads.md](https://github.com/rust-lang/rust/pull/112922/files#diff-a48ee9d94f13e12be24eadd08eb47b479c153c340eeea4ef22276d876dfd4f3e). > - Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions. > - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements. > - Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages. > - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications. > - Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target. > - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target. I acknowledge these requirements and intend to ensure they are met.

patrickelectric · 2024-05-23T00:35:51Z

any update on that ?

alexeiaguiar · 2024-05-23T01:00:14Z

Take a look at these new targets, like this one:

https://doc.rust-lang.org/rustc/platform-support/wasm32-wasip1-threads.html

abrown added major-change A proposal to make a major change to rustc T-compiler Add this label so rfcbot knows to poll the compiler team labels Dec 21, 2022

rustbot added the to-announce Announce this issue on triage meeting label Dec 21, 2022

abrown mentioned this issue Dec 21, 2022

How to distribute THREAD_MODEL=posix builds? WebAssembly/wasi-libc#326

Closed

apiraino removed the to-announce Announce this issue on triage meeting label Jan 4, 2023

abrown mentioned this issue Jan 11, 2023

Add the wasm32-wasi-pthread output to the sysroot WebAssembly/wasi-sdk#287

Closed

rustbot added the final-comment-period The FCP has started, most (if not all) team members are in agreement label Jan 11, 2023

abrown mentioned this issue Jan 11, 2023

threads: change wasm32-wasi-pthread to wasm32-wasi-threads WebAssembly/wasi-libc#381

Merged

abrown mentioned this issue Jan 23, 2023

Tracking issue for WebAssembly atomics rust-lang/rust#77839

Open

apiraino closed this as completed Jan 24, 2023

rustbot added major-change-accepted A major change proposal that was accepted to-announce Announce this issue on triage meeting and removed final-comment-period The FCP has started, most (if not all) team members are in agreement labels Jan 24, 2023

apiraino removed the to-announce Announce this issue on triage meeting label Feb 3, 2023

sergree mentioned this issue Feb 14, 2023

A shim mode for targets without threading support rayon-rs/rayon#861

Closed

MaxDesiatov mentioned this issue Mar 24, 2023

[Unix] Move all ELF SDK runtime libraries into their own architecture-specific directories swiftlang/swift#63782

Closed

yoshuawuyts mentioned this issue Apr 3, 2023

Rename wasm32-wasi target to wasm32-wasi-preview1 #607

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3 tasks

This was referenced Apr 20, 2023

Consider using wasm threads in the wasm node smol-dot/smoldot#91

Closed

Fix std compilation error for wasi+atomics rust-lang/rust#110587

Merged

abrown mentioned this issue Apr 24, 2023

Thread-Local Variable Destructors WebAssembly/wasi-threads#43

Open

g0djan mentioned this issue Jun 22, 2023

WASI threads, implementation of wasm32-wasi-preview1-threads target rust-lang/rust#112922

Merged

yoshuawuyts mentioned this issue Jul 12, 2023

Rename wasm32-wasi to wasm32-wasi-preview1 rust-lang/rust#110596

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codefromthecrypt mentioned this issue Jul 13, 2023

change module name to wasi_snapshot_preview1 WebAssembly/wasi-threads#47

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loganek mentioned this issue Aug 4, 2023

Move a wasm32-wasi-preview1-threads target to tier 2 #661

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3 tasks

BarbossHack mentioned this issue Aug 10, 2023

meta: Stabilize WASI support tokio-rs/tokio#4827

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6 tasks

cuviper mentioned this issue Aug 27, 2023

rayon_wasm : "Operation not supported on this platform" when setting number of global threads to be used rayon-rs/rayon#1081

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g0djan mentioned this issue Aug 29, 2023

MCP661: Move wasm32-wasi-preview1-threads target to Tier 2 rust-lang/rust#115345

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New tier-2 target for `wasm32-wasi` + threads #574

New tier-2 target for `wasm32-wasi` + threads #574

abrown commented Dec 21, 2022 •

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rustbot commented Dec 21, 2022

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eloparco commented Mar 21, 2023

abrown commented Mar 21, 2023

eloparco commented Mar 21, 2023

patrickelectric commented May 23, 2024

alexeiaguiar commented May 23, 2024

New tier-2 target for wasm32-wasi + threads #574

New tier-2 target for wasm32-wasi + threads #574

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abrown commented Dec 21, 2022 • edited Loading

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rustbot commented Dec 21, 2022

nagisa commented Jan 11, 2023

apiraino commented Jan 24, 2023

eloparco commented Mar 21, 2023

abrown commented Mar 21, 2023

eloparco commented Mar 21, 2023

patrickelectric commented May 23, 2024

alexeiaguiar commented May 23, 2024

New tier-2 target for `wasm32-wasi` + threads #574

New tier-2 target for `wasm32-wasi` + threads #574

abrown commented Dec 21, 2022 •

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