Remove reference type when checking const structs

[rtrieu]

Summary

ConstStructBuilder::Finalize in CGExprConstant.ccp assumes that the passed in QualType is a RecordType. In some instances, the type is a reference to a RecordType and the reference needs to be removed first.

[alexfh]

Looks good. Thanks for the fix!

clang/lib/CodeGen/CGExprConstant.cpp

if (!Field->isBitField()) {
         return false;
     }
   }
 
   return true;
 }
 
 llvm::Constant *ConstStructBuilder::Finalize(QualType Type) {
+  Type = Type.getNonReferenceType();
   RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
   llvm::Type *ValTy = CGM.getTypes().ConvertType(Type);
   return Builder.build(ValTy, RD->hasFlexibleArrayMember());
 }
 
 llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter,
                                                 InitListExpr *ILE,
                                                 QualType ValTy) {

clang/test/CodeGenCXX/merge-all-constants-references.cpp

+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fmerge-all-constants %s -o /dev/null
+
+struct A {
+};
+
+struct B {
+  const struct A& a = {};
+};
+
+void Test(const struct B&);
+
+void Run() {
+  Test({});
+}