[HLSL][NFC] Refactor HLSLExternalSemaSource (#131032)

Moving builder classes into separate files
`HLSLBuiltinTypeDeclBuilder.cpp`/`.h`, changing a some
`HLSLExternalSemaSource` methods to private and removing unused methods.

This is a prep work before we start adding more builtin types and
methods, like textures, resource constructors or matrices. For example
constructors could make use of the `BuiltinTypeMethodBuilder`, but this
helper class was defined in `HLSLExternalSemaSource.cpp` after the
method that creates a constructor. Rather than reshuffling the code one
big source file I am moving the builders into a separate cpp & header
file and placing the helper classes declarations up top.

Currently the new header only exposes `BuiltinTypeDeclBuilder` to
`HLSLExternalSemaSource`. In the future but we might decide to expose
more helper classes as needed.

Author: hekota

clang/include/clang/Sema/HLSLExternalSemaSource.h

@@ -12,9 +12,8 @@
 #ifndef CLANG_SEMA_HLSLEXTERNALSEMASOURCE_H
 #define CLANG_SEMA_HLSLEXTERNALSEMASOURCE_H
 
-#include "llvm/ADT/DenseMap.h"
-
 #include "clang/Sema/ExternalSemaSource.h"
+#include "llvm/ADT/DenseMap.h"
 
 namespace clang {
 class NamespaceDecl;
@@ -27,14 +26,8 @@ class HLSLExternalSemaSource : public ExternalSemaSource {
   using CompletionFunction = std::function<void(CXXRecordDecl *)>;
   llvm::DenseMap<CXXRecordDecl *, CompletionFunction> Completions;
 
-  void defineHLSLVectorAlias();
-  void defineTrivialHLSLTypes();
-  void defineHLSLTypesWithForwardDeclarations();
-
-  void onCompletion(CXXRecordDecl *Record, CompletionFunction Fn);
-
 public:
-  ~HLSLExternalSemaSource() override;
+  ~HLSLExternalSemaSource() override {}
 
   /// Initialize the semantic source with the Sema instance
   /// being used to perform semantic analysis on the abstract syntax
@@ -47,6 +40,12 @@ class HLSLExternalSemaSource : public ExternalSemaSource {
   using ExternalASTSource::CompleteType;
   /// Complete an incomplete HLSL builtin type
   void CompleteType(TagDecl *Tag) override;
+
+private:
+  void defineTrivialHLSLTypes();
+  void defineHLSLVectorAlias();
+  void defineHLSLTypesWithForwardDeclarations();
+  void onCompletion(CXXRecordDecl *Record, CompletionFunction Fn);
 };
 
 } // namespace clang

clang/lib/Sema/CMakeLists.txt

@@ -20,6 +20,7 @@ add_clang_library(clangSema
   DeclSpec.cpp
   DelayedDiagnostic.cpp
   HeuristicResolver.cpp
+  HLSLBuiltinTypeDeclBuilder.cpp
   HLSLExternalSemaSource.cpp
   IdentifierResolver.cpp
   JumpDiagnostics.cpp