Add method to forget generated declarations

Author: hahnjo

clang/include/clang/CodeGen/ModuleBuilder.h

@@ -106,6 +106,7 @@ class CodeGenerator : public ASTConsumer {
                             const CodeGenOptions& CGO);
 
   void forgetGlobal(llvm::GlobalValue* GV);
+  void forgetDecl(llvm::StringRef MangledName);
 };
 
 /// CreateLLVMCodeGen - Create a CodeGenerator instance.

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -283,6 +283,11 @@ namespace clang {
       }
     }
 
+    void forgetDecl(llvm::StringRef MangledName) {
+      Builder->DeferredDecls.erase(MangledName);
+      Builder->Manglings.erase(MangledName);
+    }
+
     void Initialize(ASTContext &Context) override {
       Ctx = &Context;
 
@@ -509,6 +514,10 @@ void CodeGenerator::forgetGlobal(llvm::GlobalValue* GV) {
   static_cast<CodeGeneratorImpl*>(this)->forgetGlobal(GV);
 }
 
+void CodeGenerator::forgetDecl(llvm::StringRef MangledName) {
+  static_cast<CodeGeneratorImpl*>(this)->forgetDecl(MangledName);
+}
+
 CodeGenerator *
 clang::CreateLLVMCodeGen(DiagnosticsEngine &Diags, llvm::StringRef ModuleName,
                          IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,