Author: Volodymyr Sapsai Date: 2025-10-14T16:14:28-07:00 New Revision: 3e5fc80dfe7536f8fcbd50fc58f7cc66e0bf8f16
URL: https://github.com/llvm/llvm-project/commit/3e5fc80dfe7536f8fcbd50fc58f7cc66e0bf8f16 DIFF: https://github.com/llvm/llvm-project/commit/3e5fc80dfe7536f8fcbd50fc58f7cc66e0bf8f16.diff LOG: [C23] Fix treating unnamed records nested in different types as compatible. (#162933) Don't compare and accept unnamed records from different types only because they are defined in `RecordDecl` `DeclContext`. During recursive comparison don't reject unnamed records defined inside other ordered containers like Objective-C classes. rdar://161592007 Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/AST/ASTContext.cpp clang/lib/AST/ASTStructuralEquivalence.cpp clang/test/C/C23/n3037.c Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index edb872c1f388d..79ff8219c9915 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -191,6 +191,8 @@ C23 Feature Support - Added ``FLT_SNAN``, ``DBL_SNAN``, and ``LDBL_SNAN`` to Clang's ``<float.h>`` header in C23 and later modes. This implements `WG14 N2710 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2710.htm>`_. +- Fixed accepting as compatible unnamed tag types with the same fields within + the same translation unit but from diff erent types. Non-comprehensive list of changes in this release ------------------------------------------------- diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp index a8b41ba18fa01..3603e9cd87978 100644 --- a/clang/lib/AST/ASTContext.cpp +++ b/clang/lib/AST/ASTContext.cpp @@ -11581,6 +11581,12 @@ QualType ASTContext::mergeTagDefinitions(QualType LHS, QualType RHS) { if (LangOpts.CPlusPlus || !LangOpts.C23) return {}; + // Nameless tags are comparable only within outer definitions. At the top + // level they are not comparable. + const TagDecl *LTagD = LHS->castAsTagDecl(), *RTagD = RHS->castAsTagDecl(); + if (!LTagD->getIdentifier() || !RTagD->getIdentifier()) + return {}; + // C23, on the other hand, requires the members to be "the same enough", so // we use a structural equivalence check. StructuralEquivalenceContext::NonEquivalentDeclSet NonEquivalentDecls; diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp index 155734679b2da..b17cd6f9cf68e 100644 --- a/clang/lib/AST/ASTStructuralEquivalence.cpp +++ b/clang/lib/AST/ASTStructuralEquivalence.cpp @@ -1763,19 +1763,6 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context, // another anonymous structure or union, respectively, if their members // fulfill the preceding requirements. ... Otherwise, the structure, union, // or enumerated types are incompatible. - - // Note: "the same tag" refers to the identifier for the structure; two - // structures without names are not compatible within a TU. In C23, if either - // declaration has no name, they're not equivalent. However, the paragraph - // after the bulleted list goes on to talk about compatibility of anonymous - // structure and union members, so this prohibition only applies to top-level - // declarations; if either declaration is not a member, they cannot be - // compatible. - if (Context.LangOpts.C23 && (!D1->getIdentifier() || !D2->getIdentifier()) && - (!D1->getDeclContext()->isRecord() || !D2->getDeclContext()->isRecord())) - return false; - - // Otherwise, check the names for equivalence. if (!NameIsStructurallyEquivalent(*D1, *D2)) return false; diff --git a/clang/test/C/C23/n3037.c b/clang/test/C/C23/n3037.c index 3748375692430..113ecf74d8bef 100644 --- a/clang/test/C/C23/n3037.c +++ b/clang/test/C/C23/n3037.c @@ -30,11 +30,24 @@ void func2(PRODUCT(int, SUM(float, double)) y) { // c17-warning {{declaration of struct foop { struct { int x; }; }; // c17-note {{previous definition is here}} struct foop { struct { int x; }; }; // c17-error {{redefinition of 'foop'}} +// Test the field lookup compatibility isn't sufficient, the structure of types should be compatible. +struct AnonymousStructNotMatchingFields { // c17-note {{previous definition is here}} + struct { // c23-note {{field has name '' here}} + int x; + }; +}; +struct AnonymousStructNotMatchingFields { // c23-error {{type 'struct AnonymousStructNotMatchingFields' has incompatible definitions}} \ + c17-error {{redefinition of 'AnonymousStructNotMatchingFields'}} + int x; // c23-note {{field has name 'x' here}} +}; + union barp { int x; float y; }; // c17-note {{previous definition is here}} union barp { int x; float y; }; // c17-error {{redefinition of 'barp'}} typedef struct q { int x; } q_t; // c17-note 2 {{previous definition is here}} typedef struct q { int x; } q_t; // c17-error {{redefinition of 'q'}} \ c17-error-re {{typedef redefinition with diff erent types ('struct (unnamed struct at {{.*}})' vs 'struct q')}} +typedef struct { int x; } untagged_q_t; // both-note {{previous definition is here}} +typedef struct { int x; } untagged_q_t; // both-error {{typedef redefinition with diff erent types}} void func3(void) { struct S { int x; }; // c17-note {{previous definition is here}} struct T { struct S s; }; // c17-note {{previous definition is here}} @@ -389,13 +402,40 @@ void nontag_both_in_params(struct { int i; } Arg1, struct { int i; } Arg2) { _Static_assert(0 == _Generic(__typeof__(Arg1), __typeof__(Arg2) : 1, default : 0)); // both-warning {{passing a type argument as the first operand to '_Generic' is a C2y extension}} } -struct InnerAnonStruct { +struct InnerUnnamedStruct { struct { int i; } untagged; -} inner_anon_tagged; +} inner_unnamed_tagged; +_Static_assert(0 == _Generic(inner_unnamed_tagged.untagged, struct { int i; } : 1, default : 0)); -_Static_assert(0 == _Generic(inner_anon_tagged.untagged, struct { int i; } : 1, default : 0)); +struct InnerUnnamedStruct_same { + struct { + int i; + } untagged; +}; +struct InnerUnnamedStruct_ diff erentNaming { + struct { + int i; + } untaggedDifferent; +}; +struct InnerUnnamedStruct_ diff erentShape { + float x; + struct { + int i; + } untagged; + int y; +}; +void compare_unnamed_struct_from_ diff erent_outer_type( + struct InnerUnnamedStruct sameOuterType, + struct InnerUnnamedStruct_same matchingType, + struct InnerUnnamedStruct_ diff erentNaming diff erentFieldName, + struct InnerUnnamedStruct_ diff erentShape diff erentType) { + inner_unnamed_tagged.untagged = sameOuterType.untagged; + inner_unnamed_tagged.untagged = matchingType.untagged; // both-error-re {{assigning to 'struct (unnamed struct at {{.*}})' from incompatible type 'struct (unnamed struct at {{.*}})'}} + inner_unnamed_tagged.untagged = diff erentFieldName.untaggedDifferent; // both-error-re {{assigning to 'struct (unnamed struct at {{.*}})' from incompatible type 'struct (unnamed struct at {{.*}})'}} + inner_unnamed_tagged.untagged = diff erentType.untagged; // both-error-re {{assigning to 'struct (unnamed struct at {{.*}})' from incompatible type 'struct (unnamed struct at {{.*}})'}} +} // Test the same thing with enumerations (test for unions is omitted because // unions and structures are both RecordDecl objects, whereas EnumDecl is not). _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
