Add #[repr(u128)]/#[repr(i128)] enums to improper_ctypes_definitions
#138282
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☔ The latest upstream changes (presumably #138714) made this pull request unmergeable. Please resolve the merge conflicts. |
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Rebased to fix merge conflict. @rustbot ready |
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@bors r+ rollup |
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…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#136083 (Suggest {to,from}_ne_bytes for transmutations between arrays and integers, etc) - rust-lang#138282 (Add `#[repr(u128)]`/`#[repr(i128)]` enums to `improper_ctypes_definitions`) - rust-lang#139700 (Autodiff flags) - rust-lang#140139 (rustc_target: Adjust RISC-V feature implication) - rust-lang#140141 (Move zkVM constants into `sys::env_consts`) - rust-lang#140150 (fix MAX_EXP and MIN_EXP docs) - rust-lang#140172 (Make algebraic functions into `const fn` items.) - rust-lang#140191 (Remove git repository from git config) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#138282 - beetrees:repr128-not-ffi-safe, r=oli-obk Add `#[repr(u128)]`/`#[repr(i128)]` enums to `improper_ctypes_definitions` This makes them warn whenever a plain `u128`/`i128` would. If the lang team decides to merge rust-lang#137306 then this can be reverted. Tracking issue: rust-lang#56071
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Rust's 128-bit integers have historically been incompatible with C [1]. However, there have been a number of changes in Rust and LLVM that mean this is no longer the case: * Incorrect alignment of `i128` on x86 [1]: adjusting Rust's alignment proposed at rust-lang/compiler-team#683, implemented at rust-lang#116672. * LLVM version of the above: resolved in LLVM, including ABI fix. Present in LLVM18 (our minimum supported version). * Incorrect alignment of `i128` on 64-bit PowerPC, SPARC, and MIPS [2]: Rust's data layouts adjusted at rust-lang#132422, rust-lang#132741, rust-lang#134115. * LLVM version of the above: done in LLVM 20 llvm/llvm-project#102783. * Incorrect return convention of `i128` on Windows: adjusted to match GCC and Clang at rust-lang#134290. At [3], the lang team considered it acceptable to remove `i128` from `improper_ctypes_definitions` if the LLVM version is known to be compatible. Time has elapsed since then and we have dropped support for LLVM versions that do not have the x86 fixes, meaning a per-llvm-version lint should no longer be necessary. The PowerPC, SPARC, and MIPS changes only came in LLVM 20 but since Rust's datalayouts have also been updated to match, we will be using the correct alignment regardless of LLVM version. `repr(i128)` was added to this lint in [4], but is also removed here. Part of the decision is that `i128` should match `__int128` in C on platforms that provide it, which documentation is updated to indicate. We will not guarantee that `i128` matches `_BitInt(128)` since that can be different from `__int128`. Some platforms (usually 32-bit) do not provide `__int128`; if any ABIs are extended in the future to define it, we will need to make sure that our ABI matches. Closes: rust-lang#134288 Closes: rust-lang#128950 [1]: rust-lang#54341 [2]: rust-lang#128950 [3]: rust-lang/lang-team#255 (comment) [4]: rust-lang#138282
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This makes them warn whenever a plain
u128/i128would. If the lang team decides to merge #137306 then this can be reverted.Tracking issue: #56071