Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -10739,7 +10739,8 @@
       while (isa<RecordDecl>(SearchDC) || isa<EnumDecl>(SearchDC))
         SearchDC = SearchDC->getParent();
     }
-  } else if (S->isFunctionPrototypeScope()) {
+  }
+  if (S->isFunctionPrototypeScope() && TUK == TUK_Definition) {
     // If this is an enum declaration in function prototype scope, set its
     // initial context to the translation unit.
     // FIXME: [citation needed]
Index: test/SemaCXX/type-definition-in-specifier.cpp
===================================================================
--- test/SemaCXX/type-definition-in-specifier.cpp
+++ test/SemaCXX/type-definition-in-specifier.cpp
@@ -23,3 +23,15 @@
 struct S5 { int x; } f1() { return S5(); } // expected-error{{result type}}
 
 void f2(struct S6 { int x; } p); // expected-error{{parameter type}}
+
+struct pr19018 {
+  short foo6 (enum bar0 {qq} bar3); // expected-error{{cannot be defined in a parameter type}}
+};
+
+struct pr19018a {
+  void func1(enum t19018 {qq} x); // expected-error{{cannot be defined in a parameter type}}
+  void func2(enum t19018 {qq} x); // expected-error{{cannot be defined in a parameter type}}
+  void func3(enum {qq} x);        // expected-error{{cannot be defined in a parameter type}}
+  void func4(struct t19018 {int qq;} x);  // expected-error{{cannot be defined in a parameter type}}
+  void func5(struct {int qq;} x); // expected-error{{cannot be defined in a parameter type}}
+};
\ No newline at end of file