[ODR] Fix using uninitialized FunctionTypeBits.FastTypeQuals in FunctionNoProtoType.

[vsapsai]

Summary

FastTypeQuals are used only by FunctionProtoType and put in
FunctionTypeBitfields in FunctionType to pack with the other bitfields.
So in ODR-hashing they should be used only for FunctionProtoType but not
for FunctionNoProtoType or for common FunctionType.

rdar://65305646

[vsapsai]

Wasn't actually able to make the test fail because Memory Sanitizer isn't supported on macOS and on Linux I cannot even build clang with MSAN enabled. The test case is reduced from an actual error we've seen internally when clang complaints Handler has different definitions in different modules. That was happening because due to uninitialized FastTypeQuals ODR-hash for different modules sometimes was different. It is a spurious error and I don't see how to create a reliable test case.

Also I don't know if we should keep FastTypeQuals in FunctionTypeBitfields or move somewhere else. Looks like it is there for a reason, so I've decided not to touch that.

[vsapsai]

The issue is addressed in D133586.

clang/lib/AST/ODRHash.cpp

void VisitDependentSizedExtVectorType(const DependentSizedExtVectorType *T) {
     AddQualType(T->getElementType());
     AddStmt(T->getSizeExpr());
     VisitType(T);
   }
 
   void VisitFunctionType(const FunctionType *T) {
     AddQualType(T->getReturnType());
     T->getExtInfo().Profile(ID);
-    Hash.AddBoolean(T->isConst());
-    Hash.AddBoolean(T->isVolatile());
-    Hash.AddBoolean(T->isRestrict());
     VisitType(T);
   }
 
   void VisitFunctionNoProtoType(const FunctionNoProtoType *T) {
     VisitFunctionType(T);
   }
 
   void VisitFunctionProtoType(const FunctionProtoType *T) {
+    Hash.AddBoolean(T->isConst());
+    Hash.AddBoolean(T->isVolatile());
+    Hash.AddBoolean(T->isRestrict());
     ID.AddInteger(T->getNumParams());
     for (auto ParamType : T->getParamTypes())
       AddQualType(ParamType);
 
     VisitFunctionType(T);
   }
 
   void VisitInjectedClassNameType(const InjectedClassNameType *T) {

clang/test/Modules/odr_hash-record.c

struct TSS1 {
   int tss1;
 };
 #elif defined(SECOND)
 typedef struct TSS1 TSS1;
 #else
 struct TSS1 *tss1;
 #endif
 
+// Function pointer in a struct.
+#if defined(FIRST)
+typedef void (*HandlerProcPtr)();
+struct Handler {
+    HandlerProcPtr procPtr;
+};
+#elif defined(SECOND)
+typedef void (*HandlerProcPtr)();
+struct Handler {
+    HandlerProcPtr procPtr;
+};
+#else
+struct Handler h;
+#endif
+
 // Keep macros contained to one file.
 #ifdef FIRST
 #undef FIRST
 #endif
 
 #ifdef SECOND
 #undef SECOND
 #endif