[PATCH] D31778: [Modules] Implement ODR-like semantics for tag types in C/ObjC

[Bruno Cardoso Lopes via Phabricator via cfe-commits]

bruno updated this revision to Diff 104881.
bruno added a comment.



> Digging into this a bit more, I think the root of the problem is that the `ND->isExternallyVisible()` call in `LookupResult::isHiddenDeclarationVisible` is wrong. Redeclaration lookup should never find hidden enumerators in C, because they do not have linkage (C11 6.2.2/6). (The same is true in C++, but I don't know whether we can apply the same thing there too, due to the different

merging rules.) A function foo in some source file should not conflict with an enumerator foo in a non-imported module, for instance.

> The linkage of an enumerator should probably be VisibleNoLinkage, and isHiddenDeclarationVisible should probably be checking hasExternalFormalLinkage...

Implemented this suggestions from last round of review. Change didn't seem to have side effects (at least from clang tests). @rsmith, what do you think? (I should probably split this small change into a different commit when the patch is accepted)


https://reviews.llvm.org/D31778

Files:
  include/clang/AST/ASTStructuralEquivalence.h
  include/clang/Basic/DiagnosticASTKinds.td
  include/clang/Basic/Visibility.h
  include/clang/Sema/Lookup.h
  include/clang/Sema/Sema.h
  lib/AST/ASTStructuralEquivalence.cpp
  lib/AST/Decl.cpp
  lib/Parse/ParseDecl.cpp
  lib/Parse/ParseDeclCXX.cpp
  lib/Sema/SemaDecl.cpp
  lib/Sema/SemaType.cpp
  test/Index/linkage.c
  test/Modules/Inputs/F.framework/Headers/F.h
  test/Modules/Inputs/F.framework/Modules/module.modulemap
  test/Modules/Inputs/F.framework/Modules/module.private.modulemap
  test/Modules/Inputs/F.framework/PrivateHeaders/NS.h
  test/Modules/elaborated-type-specifier-from-hidden-module.m
  test/Modules/redefinition-c-tagtypes.m
  test/Modules/redefinition-same-header.m

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