Split DWARFImporterDelegate into two parts. NFC

1. SwiftDWARFImporterForClangTypes is owned by a TypeSystemSwiftTypeRef.
   It imports Clang types from DWARF.

2. SwiftDWARFImporterDelegate is a swift::DWARFImporterDelegate that uses
   clang::ASTImporter to import a type from the TypeSystemClang used by
   the DWARFParser into the clang ASTContext used by one SwiftASTContext's
   ClangImporter.

This is in preparation for creating more flexible SwiftASTContexts in the future.

Author: adrian-prantl

lldb/source/Plugins/TypeSystem/Swift/CMakeLists.txt

@@ -1,5 +1,5 @@
 add_lldb_library(lldbPluginTypeSystemSwift PLUGIN
-  DWARFImporterDelegate.cpp
+  SwiftDWARFImporterForClangTypes.cpp
   TypeSystemSwift.cpp
   TypeSystemSwiftTypeRef.cpp
   SwiftASTContext.cpp

lldb/source/Plugins/TypeSystem/Swift/DWARFImporterDelegate.cpp

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "Plugins/TypeSystem/Swift/SwiftASTContext.h"
+#include "Plugins/TypeSystem/Swift/SwiftDWARFImporterForClangTypes.h"
 #include "Plugins/TypeSystem/Swift/StoringDiagnosticConsumer.h"
 #include "Plugins/ExpressionParser/Swift/SwiftPersistentExpressionState.h"
 
@@ -2939,12 +2940,13 @@ swift::ASTContext *SwiftASTContext::GetASTContext() {
     if (!clang_importer_options.OverrideResourceDir.empty()) {
       // Create the DWARFImporterDelegate.
       const auto &props = ModuleList::GetGlobalModuleListProperties();
-      swift::DWARFImporterDelegate *delegate = nullptr;
       if (props.GetUseSwiftDWARFImporter())
-        delegate = &m_typeref_typesystem->GetDWARFImporterDelegate();
+        m_dwarfimporter_delegate_up =
+            std::make_unique<SwiftDWARFImporterDelegate>(*this);
       auto importer_diags = getScopedDiagnosticConsumer();
       clang_importer_ap = swift::ClangImporter::create(
-          *m_ast_context_ap, "", m_dependency_tracker.get(), delegate);
+          *m_ast_context_ap, "", m_dependency_tracker.get(),
+          m_dwarfimporter_delegate_up.get());
 
       // Handle any errors.
       if (!clang_importer_ap || importer_diags->HasErrors()) {

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -84,7 +84,6 @@ namespace lldb_private {
 struct SourceModule;
 class SwiftASTContext;
 class ClangExternalASTSourceCallbacks;
-
 CompilerType ToCompilerType(swift::Type qual_type);
 
 namespace detail {
@@ -904,6 +903,7 @@ class SwiftASTContext : public TypeSystemSwift {
   swift::ClangImporter *m_clangimporter = nullptr;
   /// Wraps the clang::ASTContext owned by ClangImporter.
   std::shared_ptr<TypeSystemClang> m_clangimporter_typesystem;
+  std::unique_ptr<swift::DWARFImporterDelegate> m_dwarfimporter_delegate_up;
   SwiftModuleMap m_swift_module_cache;
   SwiftTypeFromMangledNameMap m_mangled_name_to_type_map;
   SwiftMangledNameFromTypeMap m_type_to_mangled_name_map;