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Jacob Pratt 43d2006c25
Rollup merge of #150436 - va-list-copy, r=workingjubilee,RalfJung 
`c_variadic`: impl `va_copy` and `va_end` as Rust intrinsics

tracking issue: https://github.com/rust-lang/rust/issues/44930

Implement `va_copy` as (the rust equivalent of) `memcpy`, which is the behavior of all current LLVM targets. By providing our own implementation, we can guarantee its behavior. These guarantees are important for implementing c-variadics in e.g. const-eval.

Discussed in [#t-compiler/const-eval > c-variadics in const-eval](https://rust-lang.zulipchat.com/#narrow/channel/146212-t-compiler.2Fconst-eval/topic/c-variadics.20in.20const-eval/with/565509704).

I've also updated the comment for `Drop` a bit. The background here is that the C standard requires that `va_end` is used in the same function (and really, in the same scope) as the corresponding `va_start` or `va_copy`. That is because historically `va_start` would start a scope, which `va_end` would then close. e.g.

https://softwarepreservation.computerhistory.org/c_plus_plus/cfront/release_3.0.3/source/incl-master/proto-headers/stdarg.sol

```c
#define         va_start(ap, parmN)     {\
        va_buf  _va;\
        _vastart(ap = (va_list)_va, (char *)&parmN + sizeof parmN)
#define         va_end(ap)      }
#define         va_arg(ap, mode)        *((mode *)_vaarg(ap, sizeof (mode)))
```

The C standard still has to consider such implementations, but for Rust they are irrelevant. Hence we can use `Clone` for `va_copy` and `Drop` for `va_end`.
2026-01-20 19:46:29 -05:00
..
rustc Auto merge of #148925 - madsmtm:jemalloc-perf, r=Kobzol 2025-11-23 20:34:07 +00:00
rustc_abi Temporarily re-export assert_matches! to reduce stabilization churn 2026-01-19 18:26:53 +11:00
rustc_arena Finish transition from semitransparent to semiopaque for rustc_macro_transparency 2026-01-08 19:14:45 +01:00
rustc_ast Rollup merge of #151171 - issue-141436, r=davidtwco 2026-01-19 20:53:23 +01:00
rustc_ast_ir Implement &pin patterns and ref pin bindings 2025-11-10 09:57:08 +08:00
rustc_ast_lowering Generate error delegation when delegation is not resolved 2026-01-20 11:32:23 +03:00
rustc_ast_passes Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_ast_pretty rename eii-extern-target 2026-01-12 08:07:23 +01:00
rustc_attr_parsing Remove #[rustc_lint_diagnostics] 2026-01-19 17:40:42 +01:00
rustc_baked_icu_data Unify the configuration of the compiler docs 2025-11-05 11:25:27 +00:00
rustc_borrowck Rollup merge of #150879 - remove_diag_lints, r=Kivooeo 2026-01-19 20:53:20 +01:00
rustc_builtin_macros Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_codegen_cranelift Rollup merge of #150436 - va-list-copy, r=workingjubilee,RalfJung 2026-01-20 19:46:29 -05:00
rustc_codegen_gcc c_variadic: use Clone instead of LLVM va_copy 2026-01-20 18:38:50 +01:00
rustc_codegen_llvm Rollup merge of #150436 - va-list-copy, r=workingjubilee,RalfJung 2026-01-20 19:46:29 -05:00
rustc_codegen_ssa Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_const_eval Rollup merge of #151119 - reflect-pointers, r=oli-obk 2026-01-19 20:53:22 +01:00
rustc_data_structures Auto merge of #151076 - cuviper:compiler-hashbrown-0.16.1, r=Amanieu 2026-01-20 05:44:13 +00:00
rustc_driver Unify the configuration of the compiler docs 2025-11-05 11:25:27 +00:00
rustc_driver_impl Rollup merge of #150895 - rustc_colored_explain, r=Kivooeo 2026-01-19 20:53:21 +01:00
rustc_error_codes Port #[instruction_set] to attribute parser 2025-12-31 03:01:05 +01:00
rustc_error_messages Remove DiagMessage::Translated in favour of DiagMessage::Str 2026-01-18 18:30:11 +01:00
rustc_errors Rollup merge of #151326 - translated, r=davidtwco 2026-01-19 20:53:24 +01:00
rustc_expand Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_feature Remove #[rustc_lint_diagnostics] 2026-01-19 17:40:42 +01:00
rustc_fluent_macro move and rename proc_macro::tracked_{env::var,path::path} 2025-11-26 22:44:25 +01:00
rustc_fs_util Avoid using env::temp when linking a binary 2025-12-24 06:41:42 +00:00
rustc_graphviz change non-canonical clone impl to {*self}, fix some doc comments 2025-12-20 13:46:22 +00:00
rustc_hashes some cleanups in compiler 2025-10-12 08:08:30 +00:00
rustc_hir Rollup merge of #149058 - amb-trait-lint, r=petrochenkov 2026-01-20 14:36:30 +01:00
rustc_hir_analysis Rollup merge of #150436 - va-list-copy, r=workingjubilee,RalfJung 2026-01-20 19:46:29 -05:00
rustc_hir_id rustc_hir_id: Add a comment explaining why the crate exists 2025-08-20 15:04:00 -07:00
rustc_hir_pretty Introduce hir::ConstArgKind::Array 2026-01-10 12:41:50 +09:00
rustc_hir_typeck Rollup merge of #149058 - amb-trait-lint, r=petrochenkov 2026-01-20 14:36:30 +01:00
rustc_incremental Implement incremental caching for derive macro expansions 2026-01-16 07:36:36 +01:00
rustc_index simplify words initialization using Rc::new_zeroed 2026-01-16 04:25:12 +05:30
rustc_index_macros Revert introduction of [workspace.dependencies]. 2025-09-02 19:12:54 +10:00
rustc_infer Temporarily re-export assert_matches! to reduce stabilization churn 2026-01-19 18:26:53 +11:00
rustc_interface Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_lexer lexer/parser: ensure deps use the same unicode version 2025-12-27 11:20:42 +01:00
rustc_lint Remove all usages of #[rustc_lint_diagnostics] 2026-01-19 17:39:54 +01:00
rustc_lint_defs Rollup merge of #149058 - amb-trait-lint, r=petrochenkov 2026-01-20 14:36:30 +01:00
rustc_llvm Avoid passing addrspacecast to lifetime intrinsics 2026-01-20 14:47:04 +01:00
rustc_log Restrict sysroot crate imports to those defined in this repo. 2025-10-15 13:17:25 +01:00
rustc_macros rustc_queries!: Don't push the (cache) modifier twice 2026-01-20 18:07:06 +11:00
rustc_metadata Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_middle Rollup merge of #150288 - offload-bench-fix, r=ZuseZ4 2026-01-20 18:00:08 +11:00
rustc_mir_build Rollup merge of #151295 - const-to-pat, r=BoxyUwU 2026-01-19 20:53:24 +01:00
rustc_mir_dataflow Temporarily re-export assert_matches! to reduce stabilization churn 2026-01-19 18:26:53 +11:00
rustc_mir_transform Auto merge of #151395 - Zalathar:rollup-8gANGZS, r=Zalathar 2026-01-20 09:01:18 +00:00
rustc_monomorphize Fix capitalization of error messages 2026-01-18 22:40:55 +01:00
rustc_next_trait_solver Fix an ICE on transmute goals with placeholders in param_env 2026-01-21 00:40:51 +09:00
rustc_parse Rollup merge of #151249 - fix/151238, r=petrochenkov 2026-01-19 20:53:24 +01:00
rustc_parse_format rustc_parse_format: improve diagnostics for unsupported python numeric grouping 2026-01-11 23:42:38 +05:30
rustc_passes Remove #[rustc_lint_diagnostics] 2026-01-19 17:40:42 +01:00
rustc_pattern_analysis Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_privacy Unify the configuration of the compiler docs 2025-11-05 11:25:27 +00:00
rustc_proc_macro Update literal-escaper version to 0.0.7 2026-01-08 14:10:33 +01:00
rustc_public Auto merge of #148766 - cjgillot:mir-const-runtime-checks, r=RalfJung,saethlin 2025-12-22 06:58:28 +00:00
rustc_public_bridge Overhaul filename handling for cross-compiler consistency 2025-12-12 07:33:09 +01:00
rustc_query_impl Use with_reduced_queries to avoid query cycles. 2026-01-16 19:21:35 +11:00
rustc_query_system Auto merge of #151076 - cuviper:compiler-hashbrown-0.16.1, r=Amanieu 2026-01-20 05:44:13 +00:00
rustc_resolve Rollup merge of #149058 - amb-trait-lint, r=petrochenkov 2026-01-20 14:36:30 +01:00
rustc_sanitizers Port #[cfi_encoding] to attribute parser 2025-12-21 22:11:33 +01:00
rustc_serialize Allow internal_features lint in doc tests 2025-11-05 11:25:29 +00:00
rustc_session Rollup merge of #147611 - stablize-remap-path-scope, r=davidtwco 2026-01-20 14:36:30 +01:00
rustc_span Remove #[rustc_lint_diagnostics] 2026-01-19 17:40:42 +01:00
rustc_symbol_mangling Remove all allows for diagnostic_outside_of_impl and untranslatable_diagnostic throughout the codebase 2026-01-19 17:39:49 +01:00
rustc_target Rollup merge of #151410 - llvm-22-fixes, r=cuviper 2026-01-20 19:50:10 +01:00
rustc_thread_pool change non-canonical clone impl to {*self}, fix some doc comments 2025-12-20 13:46:22 +00:00
rustc_trait_selection Rollup merge of #150879 - remove_diag_lints, r=Kivooeo 2026-01-19 20:53:20 +01:00
rustc_traits implied bounds comments 2026-01-19 16:08:54 +00:00
rustc_transmute Clean up src/dst transmute mess. 2026-01-12 09:22:58 +11:00
rustc_ty_utils Temporarily re-export assert_matches! to reduce stabilization churn 2026-01-19 18:26:53 +11:00
rustc_type_ir Rollup merge of #150861 - folding-cleanups, r=lcnr 2026-01-12 13:32:07 +01:00
rustc_type_ir_macros Provide an extended framework for type visit, for use in rust-analyzer 2025-12-16 01:47:28 +02:00
rustc_windows_rc [win] Use find-msvc-tools instead of cc to find the linker and rc on Windows 2025-09-19 12:00:30 -07:00