re PR c++/70528 (bogus error: constructor required before non-static data member)

	PR c++/70528

	* class.c (type_has_constexpr_default_constructor): Return true
	for an implicitly declared constructor.

From-SVN: r235002

gcc/cp/ChangeLog

 2016-04-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/70528
+	* class.c (type_has_constexpr_default_constructor): Return true
+	for an implicitly declared constructor.
+
 	PR c++/70622
 	* parser.c (cp_parser_init_declarator): Add auto_result parm.
 	(cp_parser_simple_declaration): Pass it.

gcc/cp/class.c

@@ -3346,7 +3346,6 @@ add_implicitly_declared_members (tree t, tree* access_decls,
       CLASSTYPE_LAZY_DEFAULT_CTOR (t) = 1;
       if (cxx_dialect >= cxx11)
 	TYPE_HAS_CONSTEXPR_CTOR (t)
-	  /* This might force the declaration.  */
 	  = type_has_constexpr_default_constructor (t);
     }
 
@@ -5349,8 +5348,11 @@ type_has_constexpr_default_constructor (tree t)
     {
       if (!TYPE_HAS_COMPLEX_DFLT (t))
 	return trivial_default_constructor_is_constexpr (t);
-      /* Non-trivial, we need to check subobject constructors.  */
-      lazily_declare_fn (sfk_constructor, t);
+      /* Assume it's constexpr to avoid unnecessary instantiation; if the
+	 definition would have made the class non-literal, it will still be
+	 non-literal because of the base or member in question, and that
+	 gives a better diagnostic.  */
+      return true;
     }
   fns = locate_ctor (t);
   return (fns && DECL_DECLARED_CONSTEXPR_P (fns));

gcc/testsuite/g++.dg/cpp0x/constexpr-ctor12.C

@@ -3,6 +3,7 @@
 
 template <typename Tp>
 struct C {
+  C() = default;
   constexpr C(const Tp& r) { }
 };
 

gcc/testsuite/g++.dg/cpp0x/constexpr-default-ctor.C

@@ -7,6 +7,6 @@ struct A {
 struct B: A { };
 constexpr int f(B b) { return b.i; }
 
-struct C { C(); };	       // { dg-message "calls non-constexpr" }
-struct D: C { };	       // { dg-message "no constexpr constructor" }
+struct C { C(); };	       // { dg-message "" }
+struct D: C { };	       // { dg-message "" }
 constexpr int g(D d) { return 42; } // { dg-error "invalid type" }

gcc/testsuite/g++.dg/cpp0x/constexpr-ice6.C

@@ -6,6 +6,6 @@ struct A
   A(int);
 };
 
-struct B : A {};                   // { dg-error "no matching" }
+struct B : A {};                   // { dg-message "" }
 
 constexpr int foo(B) { return 0; } // { dg-error "invalid type" }

gcc/testsuite/g++.dg/cpp0x/inh-ctor19.C

@@ -8,7 +8,7 @@ struct A
 
 struct B : A
 {
-  using A::A;   // { dg-error "inherited" }
+  using A::A;
 };
 
 constexpr B b;  // { dg-error "literal" }

gcc/testsuite/g++.dg/cpp0x/pr70528.C

+// PR c++/70258
+// { dg-do compile { target c++11 } }
+
+template <class T>
+struct H
+{
+  template <typename A = T, typename = decltype (A())>
+  H ();
+};
+
+struct J {
+  struct K {
+    int First = 0;
+  };
+  H<K> FunctionMDInfo;
+};