[lldb][NFC] Refactor some IsClangType checks in ClangASTContext

Summary:
All type in these functions need be valid and Clang types, so
we might as well replace these checks with IsClangType.

Also lets IsClangType explicitly check for validity instead of
assuming that the TypeSystem is a nullptr.

Subscribers: abidh, JDevlieghere, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D70001

Author: Teemperor

lldb/source/Symbol/ClangASTContext.cpp

@@ -3601,7 +3601,7 @@ bool ClangASTContext::IsDefined(lldb::opaque_compiler_type_t type) {
 }
 
 bool ClangASTContext::IsObjCClassType(const CompilerType &type) {
-  if (type) {
+  if (ClangUtil::IsClangType(type)) {
     clang::QualType qual_type(ClangUtil::GetCanonicalQualType(type));
 
     const clang::ObjCObjectPointerType *obj_pointer_type =
@@ -3886,7 +3886,7 @@ bool ClangASTContext::IsBeingDefined(lldb::opaque_compiler_type_t type) {
 
 bool ClangASTContext::IsObjCObjectPointerType(const CompilerType &type,
                                               CompilerType *class_type_ptr) {
-  if (!type)
+  if (!ClangUtil::IsClangType(type))
     return false;
 
   clang::QualType qual_type(ClangUtil::GetCanonicalQualType(type));

lldb/source/Symbol/ClangUtil.cpp

@@ -15,6 +15,10 @@ using namespace clang;
 using namespace lldb_private;
 
 bool ClangUtil::IsClangType(const CompilerType &ct) {
+  // Invalid types are never Clang types.
+  if (!ct)
+    return false;
+
   if (llvm::dyn_cast_or_null<ClangASTContext>(ct.GetTypeSystem()) == nullptr)
     return false;