[ClangModuleLoader] Provide a function to allow access to the clang::CompilerInstance, NFC.

Author: akyrtzi

include/swift/AST/ClangModuleLoader.h

@@ -17,6 +17,7 @@
 
 namespace clang {
 class ASTContext;
+class CompilerInstance;
 class Preprocessor;
 class Sema;
 } // namespace clang
@@ -32,6 +33,7 @@ class ClangModuleLoader : public ModuleLoader {
   virtual clang::ASTContext &getClangASTContext() const = 0;
   virtual clang::Preprocessor &getClangPreprocessor() const = 0;
   virtual clang::Sema &getClangSema() const = 0;
+  virtual const clang::CompilerInstance &getClangInstance() const = 0;
   virtual void printStatistics() const = 0;
 
   /// Returns the module that contains imports and declarations from all loaded

include/swift/ClangImporter/ClangImporter.h

@@ -241,6 +241,7 @@ class ClangImporter final : public ClangModuleLoader {
   clang::ASTContext &getClangASTContext() const override;
   clang::Preprocessor &getClangPreprocessor() const override;
   clang::Sema &getClangSema() const override;
+  const clang::CompilerInstance &getClangInstance() const override;
   clang::CodeGenOptions &getClangCodeGenOpts() const;
 
   std::string getClangModuleHash() const;

lib/ClangImporter/ClangImporter.cpp

@@ -2373,6 +2373,11 @@ clang::ASTContext &ClangImporter::getClangASTContext() const {
 clang::Preprocessor &ClangImporter::getClangPreprocessor() const {
   return Impl.getClangPreprocessor();
 }
+
+const clang::CompilerInstance &ClangImporter::getClangInstance() const {
+  return *Impl.Instance;
+}
+
 const clang::Module *ClangImporter::getClangOwningModule(ClangNode Node) const {
   return ::getClangOwningModule(Node, getClangASTContext());
 }