Core DR 393 - parameter pointer to array of unknown bound

	* decl.c (grokparms): Downgrade error about array of unknown bound
	to pedwarn and disable it for C++17.

From-SVN: r250137

gcc/cp/ChangeLog

+2017-07-11  Jason Merrill  <jason@redhat.com>
+
+	Core DR 393
+	* decl.c (grokparms): Downgrade error about array of unknown bound
+	to pedwarn and disable it for C++17.
+
 2017-07-11  Nathan Sidwell  <nathan@acm.org>
 
 	* decl2.c (reset_type_linkage_2): Dont't change ctor name.

gcc/cp/decl.c

@@ -12591,9 +12591,11 @@ grokparms (tree parmlist, tree *parms)
 	    }
 	  else if (abstract_virtuals_error (decl, type))
 	    any_error = 1;  /* Seems like a good idea.  */
-	  else if (POINTER_TYPE_P (type))
+	  else if (cxx_dialect < cxx1z
+		   && POINTER_TYPE_P (type))
 	    {
-	      /* [dcl.fct]/6, parameter types cannot contain pointers
+	      /* Before C++17 DR 393:
+		 [dcl.fct]/6, parameter types cannot contain pointers
 		 (references) to arrays of unknown bound.  */
 	      tree t = TREE_TYPE (type);
 	      int ptr = TYPE_PTR_P (type);
@@ -12609,12 +12611,13 @@ grokparms (tree parmlist, tree *parms)
 		  t = TREE_TYPE (t);
 		}
 	      if (TREE_CODE (t) == ARRAY_TYPE)
-		error (ptr
-                       ? G_("parameter %qD includes pointer to array of "
-                            "unknown bound %qT")
-                       : G_("parameter %qD includes reference to array of "
-                            "unknown bound %qT"),
-                       decl, t);
+		pedwarn (DECL_SOURCE_LOCATION (decl), OPT_Wpedantic,
+			 ptr
+			 ? G_("parameter %qD includes pointer to array of "
+			      "unknown bound %qT")
+			 : G_("parameter %qD includes reference to array of "
+			      "unknown bound %qT"),
+			 decl, t);
 	    }
 
 	  if (any_error)

gcc/testsuite/g++.dg/cpp1z/dr393.C

+// DR 393
+// { dg-options -Wpedantic }
+
+void f(int (&)[]);  // { dg-warning "unknown bound" "" { target c++14_down } }