document core::ffi::VaArgSafe
#146521
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document core::ffi::VaArgSafe
#146521
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and document `VaList::arg`.
as far as I can see this was not tested, though the error message was already implemented
…unctions they don't do anything, because LLVM is unable to inline c-variadic functions (on most targets, anyway)
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Thanks! I think I will go ahead and shove this into the queue since this is an already discussed, docs-and-tests-only change. @bors r+ rollup |
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Rollup of 8 pull requests Successful merges: - #113095 (Document `become` keyword) - #146159 (Some hygiene doc improvements) - #146171 (tidy: check that error messages don't start with a capitalized letter) - #146419 (Update the arm-* and aarch64-* platform docs.) - #146473 (Revert "Constify SystemTime methods") - #146506 (Fix small typo in check-cfg.md) - #146517 (fix Condvar::wait_timeout docs) - #146521 (document `core::ffi::VaArgSafe`) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of #146521 - folkertdev:document-va-arg-safe, r=workingjubilee document `core::ffi::VaArgSafe` tracking issue: #44930 A modification of #146454, keeping just the documentation changes, but not unsealing the trait. Although conceptually we'd want to unseal the trait, there are many edge cases to supporting arbitrary types. We'd need to exhaustively test that all targets/calling conventions support all types that rust might generate (or generate proper error messages for unsupported cases). At present, many of the `va_arg` implementations assume that the argument is a scalar, and has an alignment of at most 8. That is totally sufficient for an MVP (accepting all of the "standard" C types), but clearly does not cover all rust types. This PR also adds some various other tests for edge cases of c-variadic: - the `#[inline]` attribute in its various forms. At present, LLVM is unable to inline c-variadic functions, but the attribute should still be accepted. `#[rustc_force_inline]` already rejects c-variadic functions. - naked functions should accept and work with a C variable argument list. In the future we'd like to allow more ABIs with naked functions (basically, any ABI for which we accept defining foreign c-variadic functions), but for now only `"C"` and `"C-unwind` are supported - guaranteed tail calls: c-variadic functions cannot be tail-called. That was already rejected, but there was not test for it. r? `@workingjubilee`
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tracking issue: #44930
A modification of #146454, keeping just the documentation changes, but not unsealing the trait.
Although conceptually we'd want to unseal the trait, there are many edge cases to supporting arbitrary types. We'd need to exhaustively test that all targets/calling conventions support all types that rust might generate (or generate proper error messages for unsupported cases). At present, many of the
va_argimplementations assume that the argument is a scalar, and has an alignment of at most 8. That is totally sufficient for an MVP (accepting all of the "standard" C types), but clearly does not cover all rust types.This PR also adds some various other tests for edge cases of c-variadic:
#[inline]attribute in its various forms. At present, LLVM is unable to inline c-variadic functions, but the attribute should still be accepted.#[rustc_force_inline]already rejects c-variadic functions."C"and"C-unwindare supportedr? @workingjubilee