re PR c++/68754 (Explicitly defaulted constexpr assignment operator fails to compile)

/cp
2017-09-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/68754
	* method.c (defaulted_late_check): Early return if the defaulted
	declaration does not match the expected signature.

/testsuite
2017-09-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/68754
	* g++.dg/cpp1y/constexpr-68754.C: Move...
	* g++.dg/cpp0x/constexpr-68754.C: ... here, adjust.

From-SVN: r253321

gcc/cp/ChangeLog

+2017-09-30  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/68754
+	* method.c (defaulted_late_check): Early return if the defaulted
+	declaration does not match the expected signature.
+
 2017-09-29  Jakub Jelinek  <jakub@redhat.com>
 
 	P0683R1 - default member initializers for bit-fields

gcc/cp/method.c

@@ -2191,9 +2191,11 @@ defaulted_late_check (tree fn)
       || !compparms (TYPE_ARG_TYPES (TREE_TYPE (fn)),
 		     TYPE_ARG_TYPES (TREE_TYPE (implicit_fn))))
     {
-      error ("defaulted declaration %q+D", fn);
-      error_at (DECL_SOURCE_LOCATION (fn),
-		"does not match expected signature %qD", implicit_fn);
+      error ("defaulted declaration %q+D does not match the "
+	     "expected signature", fn);
+      inform (DECL_SOURCE_LOCATION (fn),
+	      "expected signature: %qD", implicit_fn);
+      return;
     }
 
   if (DECL_DELETED_FN (implicit_fn))

gcc/testsuite/ChangeLog

+2017-09-30  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/68754
+	* g++.dg/cpp1y/constexpr-68754.C: Move...
+	* g++.dg/cpp0x/constexpr-68754.C: ... here, adjust.
+
 2017-09-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/82361

gcc/testsuite/g++.dg/cpp1y/constexpr-68754.C → gcc/testsuite/g++.dg/cpp0x/constexpr-68754.C

 // PR c++/68754
-// { dg-do compile { target c++14 } }
+// { dg-do compile { target c++11 } }
 
 struct base { };
 struct derived : base {
-  constexpr derived& operator=(derived const&) = default;
+  constexpr derived& operator=(derived const&) = default; // { dg-error "defaulted declaration" "" { target { ! c++14 } } }
 };