Don't parse elements of extended vectors as template names

[ahatanak]

Summary

This patch attempts to fix the bug introduced in r360308, which is causing clang to reject the following piece of code:

typedef __attribute__((__ext_vector_type__(2))) float vector_float2;

bool foo123(vector_float2 &A, vector_float2 &B)
{
  return A.x < B.x && B.y > A.y;
}

The patch sets ObjectType to the type of the extended vector in Sema::ActOnStartCXXMemberReference so that Sema::isTemplateName, which is called later ,returns false.

rdar://problem/52619956

lib/Sema/SemaExprCXX.cpp

ExprResult Sema::ActOnStartCXXMemberReference(Scope *S, Expr *Base,
   // expressions or normal member (ivar or property) access expressions, and
   // it's legal for the type to be incomplete if this is a pseudo-destructor
   // call.  We'll do more incomplete-type checks later in the lookup process,
   // so just skip this check for ObjC types.
   if (BaseType->isObjCObjectOrInterfaceType()) {
     ObjectType = ParsedType::make(BaseType);
     MayBePseudoDestructor = true;
     return Base;
-  } else if (!BaseType->isRecordType()) {
+  }
+
+  if (BaseType->isExtVectorType()) {
+    ObjectType = ParsedType::make(BaseType);
+    MayBePseudoDestructor = true;
+    return Base;
+  }
+
+  if (!BaseType->isRecordType()) {
     ObjectType = nullptr;
     MayBePseudoDestructor = true;
     return Base;
   }
 
   // The object type must be complete (or dependent), or
   // C++11 [expr.prim.general]p3:
   //   Unlike the object expression in other contexts, *this is not required to

test/SemaCXX/vector.cpp

void Init() {
   // expected-error@305 {{vector size not an integral multiple of component size}}
   // expected-note@+1 {{in instantiation of template class 'Templates::PR15730<8, int>' requested here}}
   const PR15730<8, int>::type PR15730_1 = {};
   // expected-error@304 {{vector size too large}}
   // expected-note@+1 {{in instantiation of template class 'Templates::PR15730<8, char>' requested here}}
   const PR15730<8, char>::type2 PR15730_2 = {};
 }
 
+// This used to be rejected because the name lookup determined 'x' in 'a.x' was
+// a template name.
+bool templateName(char16_e a, char16_e b) {
+  return a.x < b.x && b.y > a.y;
+}
+
 } // namespace Templates