Author: Thomas Preud'homme Date: 2020-12-04T14:34:51Z New Revision: 507bbc45bba90fab3f1a2b42e94ae4fbebdd6498
URL: https://github.com/llvm/llvm-project/commit/507bbc45bba90fab3f1a2b42e94ae4fbebdd6498 DIFF: https://github.com/llvm/llvm-project/commit/507bbc45bba90fab3f1a2b42e94ae4fbebdd6498.diff LOG: [AST][NFC] Silence GCC warning about broken strict aliasing rules The deserialize() method would trigger the following warning on GCC <7: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] ParamIdx P(*reinterpret_cast<ParamIdx *>(&S)); ^ &S was previously reinterpret_casted from a ParamIdx into a SerialType, it is therefore safe to cast back into a ParamIdx. Similar to what was done in D50608, we replace it with two static_cast via void * which silences the warning and presumably makes GCC understand that no strict-aliasing violation is happening. No functional change intended. Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D92384 Added: Modified: clang/include/clang/AST/Attr.h Removed: ################################################################################ diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h index 545dc992c5ed..8d9fb8f2bf27 100644 --- a/clang/include/clang/AST/Attr.h +++ b/clang/include/clang/AST/Attr.h @@ -259,7 +259,10 @@ class ParamIdx { /// Construct from a result from \c serialize. static ParamIdx deserialize(SerialType S) { - ParamIdx P(*reinterpret_cast<ParamIdx *>(&S)); + // Using this two-step static_cast via void * instead of reinterpret_cast + // silences a -Wstrict-aliasing false positive from GCC7 and earlier. + void *ParamIdxPtr = static_cast<void *>(&S); + ParamIdx P(*static_cast<ParamIdx *>(ParamIdxPtr)); assert((!P.IsValid || P.Idx >= 1) && "valid Idx must be one-origin"); return P; } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
