Merged to 6.0 in r324213.
On Fri, Feb 2, 2018 at 9:30 PM, Eric Fiselier via cfe-commits <cfe-commits@lists.llvm.org> wrote: > Author: ericwf > Date: Fri Feb 2 12:30:39 2018 > New Revision: 324134 > > URL: http://llvm.org/viewvc/llvm-project?rev=324134&view=rev > Log: > Make __has_unique_object_representations reject empty union types. > > Summary: > Clang incorrectly reports empty unions as having a unique object > representation. However, this is not correct since `sizeof(EmptyUnion) == 1` > AKA it has 8 bits of padding. Therefore it should be treated the same as an > empty struct and report `false`. > > @erichkeane also suggested this fix should be merged into the 6.0 release > branch, so the initial release of `__has_unique_object_representations` is as > bug-free as possible. > > Reviewers: erichkeane, rsmith, aaron.ballman, majnemer > > Reviewed By: erichkeane > > Subscribers: cfe-commits, erichkeane > > Differential Revision: https://reviews.llvm.org/D42863 > > Modified: > cfe/trunk/lib/AST/ASTContext.cpp > cfe/trunk/test/SemaCXX/type-traits.cpp > > Modified: cfe/trunk/lib/AST/ASTContext.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ASTContext.cpp?rev=324134&r1=324133&r2=324134&view=diff > ============================================================================== > --- cfe/trunk/lib/AST/ASTContext.cpp (original) > +++ cfe/trunk/lib/AST/ASTContext.cpp Fri Feb 2 12:30:39 2018 > @@ -2145,7 +2145,7 @@ static bool unionHasUniqueObjectRepresen > if (FieldSize != UnionSize) > return false; > } > - return true; > + return !RD->field_empty(); > } > > static bool isStructEmpty(QualType Ty) { > > Modified: cfe/trunk/test/SemaCXX/type-traits.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/type-traits.cpp?rev=324134&r1=324133&r2=324134&view=diff > ============================================================================== > --- cfe/trunk/test/SemaCXX/type-traits.cpp (original) > +++ cfe/trunk/test/SemaCXX/type-traits.cpp Fri Feb 2 12:30:39 2018 > @@ -2566,6 +2566,7 @@ static_assert(!has_unique_object_represe > static_assert(!has_unique_object_representations<volatile int &>::value, "No > references!"); > static_assert(!has_unique_object_representations<const volatile int > &>::value, "No references!"); > static_assert(!has_unique_object_representations<Empty>::value, "No empty > types!"); > +static_assert(!has_unique_object_representations<EmptyUnion>::value, "No > empty types!"); > > class Compressed : Empty { > int x; > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
