2 files changed, 17 insertions, 0 deletions
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index f903035d22..dc614018ec 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -355,6 +355,10 @@ bool LValueExprEvaluator::VisitDeclRefExpr(DeclRefExpr *E) {
   } else if (VarDecl* VD = dyn_cast<VarDecl>(E->getDecl())) {
     if (!VD->getType()->isReferenceType())
       return Success(E);
+    // Reference parameters can refer to anything even if they have an
+    // "initializer" in the form of a default argument.
+    if (isa<ParmVarDecl>(VD))
+      return false;
     // FIXME: Check whether VD might be overridden!
     if (const Expr *Init = VD->getAnyInitializer())
       return Visit(const_cast<Expr *>(Init));
diff --git a/test/CodeGenCXX/references.cpp b/test/CodeGenCXX/references.cpp
index 5a5947dd81..3ae1e474f8 100644
--- a/test/CodeGenCXX/references.cpp
+++ b/test/CodeGenCXX/references.cpp
@@ -155,3 +155,16 @@ void f0(s1 a) { s1 b = a; }
 // CHECK: load
 // CHECK: ret
 const int &f2() { return 0; }
+
+// Don't constant fold const reference parameters with default arguments to
+// their default arguments.
+namespace N1 {
+  const int foo = 1;
+  // CHECK: @_ZN2N14test
+  int test(const int& arg = foo) {
+    // Ensure this array is on the stack where we can set values instead of
+    // being a global constant.
+    // CHECK: %args_array = alloca
+    const int* const args_array[] = { &arg };
+  }
+}