Allow tag-based API notes on anonymous tag decls with typedef names

It is common practice in C to declare anonymous tags that are
immediately given a typedef name, e.g.,

    typedef enum { ... } MyType;

At present, one can only express API notes on the typedef. However, that
excludes the possibility of tag-specific notes like EnumExtensibility.
For these anonymous declarations, process API notes using the typedef
name as the tag name, so that one can add API notes to `MyType` via the
`Tags` section.

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index e4c45cb..add28b3 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -4974,6 +4974,9 @@ void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
 
   // Otherwise, set this as the anon-decl typedef for the tag.
   TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
+
+  // Now that we have a name for the tag, process API notes again.
+  ProcessAPINotes(TagFromDeclSpec);
 }
 
 static unsigned GetDiagnosticTypeSpecifierID(const DeclSpec &DS) {