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Tracking Issue for extern_system_varargs #136946

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workingjubilee opened this issue Feb 12, 2025 · 8 comments
Open
1 of 4 tasks

Tracking Issue for extern_system_varargs #136946

workingjubilee opened this issue Feb 12, 2025 · 8 comments
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A-ABI Area: Concerning the application binary interface (ABI) C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-lang Relevant to the language team, which will review and decide on the PR/issue.

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@workingjubilee
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workingjubilee commented Feb 12, 2025 •
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This is a tracking issue for enabling using an extern "system" function with varargs.
The feature gate for the issue is #![feature(extern_system_varargs)].

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.

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@workingjubilee workingjubilee added A-ABI Area: Concerning the application binary interface (ABI) C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC labels Feb 12, 2025
@workingjubilee workingjubilee mentioned this issue Feb 12, 2025
Merged
jhpratt added a commit to jhpratt/rust that referenced this issue Feb 13, 2025
@jhpratt
Rollup merge of rust-lang#136948 - workingjubilee:split-off-extern-sy…
e8094a5 
…stem-varargs, r=compiler-errors

Split out the `extern_system_varargs` feature

After the stabilization PR was opened, `extern "system"` functions were added to `extended_varargs_abi_support`. This has a number of questions regarding it that were not discussed and were somewhat surprising. It deserves to be considered as its own feature, separate from `extended_varargs_abi_support`.

Tracking issue:
- rust-lang#136946
jhpratt added a commit to jhpratt/rust that referenced this issue Feb 13, 2025
@jhpratt
Rollup merge of rust-lang#136948 - workingjubilee:split-off-extern-sy…
36d3796 
…stem-varargs, r=compiler-errors

Split out the `extern_system_varargs` feature

After the stabilization PR was opened, `extern "system"` functions were added to `extended_varargs_abi_support`. This has a number of questions regarding it that were not discussed and were somewhat surprising. It deserves to be considered as its own feature, separate from `extended_varargs_abi_support`.

Tracking issue:
- rust-lang#136946
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Feb 13, 2025
@rust-timer
Unrolled build for rust-lang#136948
4d37ccb 
Rollup merge of rust-lang#136948 - workingjubilee:split-off-extern-system-varargs, r=compiler-errors

Split out the `extern_system_varargs` feature

After the stabilization PR was opened, `extern "system"` functions were added to `extended_varargs_abi_support`. This has a number of questions regarding it that were not discussed and were somewhat surprising. It deserves to be considered as its own feature, separate from `extended_varargs_abi_support`.

Tracking issue:
- rust-lang#136946
@RalfJung
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RalfJung commented Feb 14, 2025 •
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we have previously rejected implementing MSVC's oddities:

You keep saying this and I keep correcting you.^^
We have implemented their oddities on Windows targets: stdcall works on x86_64-pc-windows-msvc and even aarch64-pc-windows-msvc. There was some discussion about this here and here.

@workingjubilee
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Yes yes, I copied some text around, so you get to copy some text around too.

If extern "stdcall" is downgraded to extern "C" anyways when variable arguments are involved on MSVC targets, why doesn't that apply to extern "stdcall" for all cases where the ABI is supported?

@workingjubilee
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At least if we did that, it would be... well, absurd, I think, but equally absurd in all cases?

@RalfJung
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RalfJung commented Feb 14, 2025 •
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I don't understand the question / proposal. This does apply in all cases, no?

@ChrisDenton
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stdcall works on x86_64-pc-windows-msvc and even aarch64-pc-windows-msvc.

That is not true for the raw-dylib feature, which is stricter.

@workingjubilee
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I don't understand the question / proposal. This does apply in all cases, no?

Currently rustc_hir_analysis will reject an attempt to use a variable argument function with extern "stdcall", such as extern "stdcall" fn(i32, ...), without further consideration.

@RalfJung
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Currently rustc_hir_analysis will reject an attempt to use a variable argument function with extern "stdcall", such as extern "stdcall" fn(i32, ...), without further consideration.

I guess the argument is that MSVC accepts varagrs for system but not for stdcall? Or is that not correct?

That is not true for the raw-dylib feature, which is stricter.

Oh, that is an odd inconsistency... I filed a separate issue for that: #137018.

@workingjubilee
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workingjubilee commented Feb 14, 2025 •
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I guess the argument is that MSVC accepts varagrs for system but not for stdcall? Or is that not correct?

extern "system" is a Rust invention, as far as I am aware.

@workingjubilee workingjubilee added T-lang Relevant to the language team, which will review and decide on the PR/issue. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 14, 2025
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this issue Feb 17, 2025
@jhpratt
Rollup merge of #136948 - workingjubilee:split-off-extern-system-vara…
663e60d 
…rgs, r=compiler-errors

Split out the `extern_system_varargs` feature

After the stabilization PR was opened, `extern "system"` functions were added to `extended_varargs_abi_support`. This has a number of questions regarding it that were not discussed and were somewhat surprising. It deserves to be considered as its own feature, separate from `extended_varargs_abi_support`.

Tracking issue:
- rust-lang/rust#136946
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A-ABI Area: Concerning the application binary interface (ABI) C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-lang Relevant to the language team, which will review and decide on the PR/issue.
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