[clang] [C23] Handle type compatibility of unnamed records (PR #141783)
Erich Keane via cfe-commits
cfe-commits at lists.llvm.org
Wed May 28 08:06:58 PDT 2025
================
@@ -1751,9 +1751,20 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
// fulfill the preceding requirements. ... Otherwise, the structure, union,
// or enumerated types are incompatible.
- if (!NameIsStructurallyEquivalent(*D1, *D2)) {
+ // 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, not members.
+ if (Context.LangOpts.C23 && (!D1->getIdentifier() || !D2->getIdentifier()) &&
+ (D1->getDeclContext()->isTranslationUnit() ||
----------------
erichkeane wrote:
Does lexical decl context come into play here at all?
Also, and this might be my C++-brain firing here, but is this sufficient? I know in C++ we typically check `isFileContextDecl` but IIRC that is just namespaces...
Also-also-- what about structs who are defined 'inline' (or whatever y'all call it)... are those never equal too? Something like defined in a param list, or in an enum-initializer, or function scope?
So I wonder if we want to invert this and check if decl-context is a RecordDecl?
https://github.com/llvm/llvm-project/pull/141783
More information about the cfe-commits
mailing list