Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -13533,8 +13533,7 @@
       return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
     }
 
-    if (Info.Ctx.getLangOpts().CPlusPlus &&
-        Info.EvalMode == EvalInfo::EM_ConstantExpression &&
+    if (Info.Ctx.getLangOpts().CPlusPlus && Info.InConstantContext &&
         DestType->isEnumeralType()) {
       const EnumType *ET = dyn_cast<EnumType>(DestType.getCanonicalType());
       const EnumDecl *ED = ET->getDecl();
Index: clang/test/SemaCXX/constant-expression-cxx11.cpp
===================================================================
--- clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -2455,4 +2455,18 @@
   constexpr EMaxInt x20 = static_cast<EMaxInt>((long)__INT_MAX__+1);
   // expected-error@-1 {{integer value 2147483648 is outside the valid range of values [-2147483648, 2147483647] for this enumeration type}}
 }
+
+enum SortOrder {
+  AscendingOrder,
+  DescendingOrder
+};
+
+class A {
+  static void f(SortOrder order);
+};
+
+void A::f(SortOrder order) {
+  if (order == SortOrder(-1)) // ok, not a constant expression context
+    return;
+}
 }