C-variadic error improvements #117370

nicholasbishop · 2023-10-29T21:46:27Z

A couple improvements for c-variadic errors:

Fix the bad-c-variadic error being emitted multiple times. If a function incorrectly contains multiple ... args, and is also not foreign or unsafe extern "C", only emit the latter error once rather than once per ....
Explicitly reject const C-variadic functions. Trying to use C-variadics in a const function would previously fail with an error like "destructor of VaListImpl<'_> cannot be evaluated at compile-time". Add an explicit check for const C-variadics to provide a clearer error: "functions cannot be both const and C-variadic". This also addresses one of the concerns in Tracking issue for RFC 2137: Support defining C-compatible variadic functions in Rust #44930: "Ensure that even when this gets stabilized for regular functions, it is still rejected on const fn."

rustbot · 2023-10-29T21:46:35Z

r? @oli-obk

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compiler/rustc_ast_passes/src/ast_validation.rs

oli-obk

lgtm. let me know about your opionion on making the diagnostic point to all the variadics at once

If a function incorrectly contains multiple `...` args, and is also not foreign or `unsafe extern "C"`, only emit the latter error once.

Trying to use C-variadics in a const function would previously fail with an error like "destructor of `VaListImpl<'_>` cannot be evaluated at compile-time". Add an explicit check for const C-variadics to provide a clearer error: "functions cannot be both `const` and C-variadic".

oli-obk · 2023-10-30T15:28:10Z

Thanks!

@bors r+ rollup

bors · 2023-10-30T15:28:12Z

📌 Commit f91b5ce has been approved by oli-obk

It is now in the queue for this repository.

…iadic-errors, r=oli-obk C-variadic error improvements A couple improvements for c-variadic errors: 1. Fix the bad-c-variadic error being emitted multiple times. If a function incorrectly contains multiple `...` args, and is also not foreign or `unsafe extern "C"`, only emit the latter error once rather than once per `...`. 2. Explicitly reject `const` C-variadic functions. Trying to use C-variadics in a const function would previously fail with an error like "destructor of `VaListImpl<'_>` cannot be evaluated at compile-time". Add an explicit check for const C-variadics to provide a clearer error: "functions cannot be both `const` and C-variadic". This also addresses one of the concerns in rust-lang#44930: "Ensure that even when this gets stabilized for regular functions, it is still rejected on const fn."

…llaumeGomez Rollup of 11 pull requests Successful merges: - rust-lang#112463 (rustdoc: elide cross-crate default generic arguments) - rust-lang#117068 (Clean up `compiler/rustc*/Cargo.toml`) - rust-lang#117132 (On object safety error, mention new enum as alternative) - rust-lang#117317 (share some track_caller logic between interpret and codegen) - rust-lang#117356 (Add support for mipsel-unknown-netbsd, 32-bit LE mips.) - rust-lang#117357 (Rename a few remaining references to abort terminator) - rust-lang#117370 (C-variadic error improvements) - rust-lang#117376 (More `rustc_interface` cleanups) - rust-lang#117383 (improve and fix `x install`) - rust-lang#117390 (Fix unused variables lint issue for args in macro) - rust-lang#117395 (Fix missing leading space in suggestion) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#117370 - nicholasbishop:bishop-better-c-variadic-errors, r=oli-obk C-variadic error improvements A couple improvements for c-variadic errors: 1. Fix the bad-c-variadic error being emitted multiple times. If a function incorrectly contains multiple `...` args, and is also not foreign or `unsafe extern "C"`, only emit the latter error once rather than once per `...`. 2. Explicitly reject `const` C-variadic functions. Trying to use C-variadics in a const function would previously fail with an error like "destructor of `VaListImpl<'_>` cannot be evaluated at compile-time". Add an explicit check for const C-variadics to provide a clearer error: "functions cannot be both `const` and C-variadic". This also addresses one of the concerns in rust-lang#44930: "Ensure that even when this gets stabilized for regular functions, it is still rejected on const fn."

rustbot assigned oli-obk Oct 29, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 29, 2023

nicholasbishop force-pushed the bishop-better-c-variadic-errors branch from bca1492 to c88bb2a Compare October 29, 2023 21:50

oli-obk reviewed Oct 30, 2023

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oli-obk approved these changes Oct 30, 2023

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nicholasbishop added 2 commits October 30, 2023 10:29

Fix bad-c-variadic error being emitted multiple times

8508e65

If a function incorrectly contains multiple `...` args, and is also not foreign or `unsafe extern "C"`, only emit the latter error once.

nicholasbishop force-pushed the bishop-better-c-variadic-errors branch from c88bb2a to f91b5ce Compare October 30, 2023 14:38

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 30, 2023

matthiaskrgr mentioned this pull request Oct 30, 2023

Rollup of 7 pull requests #117402

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This was referenced Oct 30, 2023

Rollup of 12 pull requests #117404

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Rollup of 11 pull requests #117405

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bors merged commit 784f04b into rust-lang:master Oct 30, 2023
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rustbot added this to the 1.75.0 milestone Oct 30, 2023

nicholasbishop deleted the bishop-better-c-variadic-errors branch October 30, 2023 20:50

github-actions bot mentioned this pull request Oct 31, 2023

Automated pull from upstream master ferrocene/ferrocene#74

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C-variadic error improvements #117370

C-variadic error improvements #117370

nicholasbishop commented Oct 29, 2023 •

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C-variadic error improvements #117370

C-variadic error improvements #117370

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