Sema: adjust assertion to account for deduced types

[compnerd]

Summary

Previous changes for the BTF attributes introduced a new sub-tree
visitation. That uncovered that when accessing the typespec location we
would assert that the type specification is either a type declaration or
typename. However, typename was explicitly permitted. This change
predates the introduction of newer deduced type representations such as
__underlying_type from C++ and the addition of the GNU __typeof__
expression.

Thanks to aaron.ballman for the valuable discussion and pointer to
isTypeRep.

[compnerd]

git-clang-format

[yonghong-song]

Sorry. I missed this patch somehow and did another patch https://reviews.llvm.org/D126223. My patch skipped TL.setNameLoc(DS.getTypeSpecTypeNameLoc()); which probably not correct. Accept this patch and abandon my patch D126223.

[aaron.ballman]

LGTM aside from a testing request and a nit. Thanks for the fix!

clang/include/clang/Sema/DeclSpec.h

520

I think you've got a test case covering isExprRep() because your __typeof__ names an expression, but can you also add coverage for isTypeRep() where __typeof__ names a type instead, as in: https://godbolt.org/z/hfK8ds9EM

clang/test/Sema/typerep-typespec.c

1

clang/include/clang/Sema/DeclSpec.h

public:
   SourceRange getTypeSpecWidthRange() const { return TSWRange; }
   SourceLocation getTypeSpecComplexLoc() const { return TSCLoc; }
   SourceLocation getTypeSpecSignLoc() const { return TSSLoc; }
   SourceLocation getTypeSpecTypeLoc() const { return TSTLoc; }
   SourceLocation getAltiVecLoc() const { return AltiVecLoc; }
   SourceLocation getTypeSpecSatLoc() const { return TSSatLoc; }
 
   SourceLocation getTypeSpecTypeNameLoc() const {
-    assert(isDeclRep((TST) TypeSpecType) || TypeSpecType == TST_typename);
+    assert(isDeclRep((TST)TypeSpecType) || isTypeRep((TST)TypeSpecType) ||
+           isExprRep((TST)TypeSpecType));
     return TSTNameLoc;
   }
 
   SourceRange getTypeofParensRange() const { return TypeofParensRange; }
   void setTypeofParensRange(SourceRange range) { TypeofParensRange = range; }
 
   bool hasAutoTypeSpec() const {
     return (TypeSpecType == TST_auto || TypeSpecType == TST_auto_type ||

clang/test/Sema/typerep-typespec.c

+// RUN: %clang_cc1 -std=c11 -x c %s -fsyntax-only -verify
+// REQUIRES: asserts
+
+struct dispatch_object_s;
+void _dispatch_queue_get_head(struct dispatch_object_s *volatile dq_items_head) {
+  (_Atomic __typeof__(dq_items_head) *)0; // expected-warning{{expression result unused}}
+}