PR c++/71147 - [6 Regression] Flexible array member wrongly rejected in template

gcc/ChangeLog:
2016-05-24  Martin Sebor  <msebor@redhat.com>

	PR c++/71147
	* gcc/tree.h (complete_or_array_type_p): New inline function.

gcc/testsuite/ChangeLog:
2016-05-24  Martin Sebor  <msebor@redhat.com>

	PR c++/71147
	* g++.dg/ext/flexary16.C: New test.

gcc/cp/ChangeLog:
2016-05-24  Martin Sebor  <msebor@redhat.com>

	PR c++/71147
	* decl.c (layout_var_decl, grokdeclarator): Use complete_or_array_type_p.
	* pt.c (instantiate_class_template_1): Try to complete the element
	type of a flexible array member.
	(can_complete_type_without_circularity): Handle arrays of unknown bound.
	* typeck.c (complete_type): Also complete the type of the elements of
	arrays with an unspecified bound.

From-SVN: r236664

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2016-05-24  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/71147
+	* gcc/tree.h (complete_or_array_type_p): New inline function.
+
 2016-05-24  Jakub Jelinek  <jakub@redhat.com>
 
 	* config/i386/i386.h (TARGET_AVOID_4BYTE_PREFIXES): Define.

gcc/cp/ChangeLog

@@ -1,3 +1,13 @@
+2016-05-24  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/71147
+	* decl.c (layout_var_decl, grokdeclarator): Use complete_or_array_type_p.
+	* pt.c (instantiate_class_template_1): Try to complete the element
+	type of a flexible array member.
+	(can_complete_type_without_circularity): Handle arrays of unknown bound.
+	* typeck.c (complete_type): Also complete the type of the elements of
+	arrays with an unspecified bound.
+
 2016-05-24  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/69872

gcc/cp/decl.c

@@ -5305,10 +5305,7 @@ layout_var_decl (tree decl)
     complete_type (type);
   if (!DECL_SIZE (decl)
       && TREE_TYPE (decl) != error_mark_node
-      && (COMPLETE_TYPE_P (type)
+      && complete_or_array_type_p (type))
-	  || (TREE_CODE (type) == ARRAY_TYPE
-	      && !TYPE_DOMAIN (type)
-	      && COMPLETE_TYPE_P (TREE_TYPE (type)))))
     layout_decl (decl, 0);
 
   if (!DECL_EXTERNAL (decl) && DECL_SIZE (decl) == NULL_TREE)
@@ -11165,8 +11162,7 @@ grokdeclarator (const cp_declarator *declarator,
 	  }
 	else if (!staticp && !dependent_type_p (type)
 		 && !COMPLETE_TYPE_P (complete_type (type))
-		 && (TREE_CODE (type) != ARRAY_TYPE
+		 && (!complete_or_array_type_p (type)
-		     || !COMPLETE_TYPE_P (TREE_TYPE (type))
 		     || initialized == 0))
 	  {
 	    if (TREE_CODE (type) != ARRAY_TYPE

gcc/cp/pt.c

@@ -9555,7 +9555,7 @@ can_complete_type_without_circularity (tree type)
     return 0;
   else if (COMPLETE_TYPE_P (type))
     return 1;
-  else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
+  else if (TREE_CODE (type) == ARRAY_TYPE)
     return can_complete_type_without_circularity (TREE_TYPE (type));
   else if (CLASS_TYPE_P (type)
 	   && TYPE_BEING_DEFINED (TYPE_MAIN_VARIANT (type)))
@@ -10120,17 +10120,12 @@ instantiate_class_template_1 (tree type)
 			  if (can_complete_type_without_circularity (rtype))
 			    complete_type (rtype);
 
-                          if (TREE_CODE (r) == FIELD_DECL
+			  if (!complete_or_array_type_p (rtype))
-                              && TREE_CODE (rtype) == ARRAY_TYPE
-                              && COMPLETE_TYPE_P (TREE_TYPE (rtype))
-                              && !COMPLETE_TYPE_P (rtype))
-                            {
-                              /* Flexible array mmembers of elements
-                                 of complete type have an incomplete type
-                                 and that's okay.  */
-                            }
-                          else if (!COMPLETE_TYPE_P (rtype))
 			    {
+			      /* If R's type couldn't be completed and
+				 it isn't a flexible array member (whose
+				 type is incomplete by definition) give
+				 an error.  */
 			      cxx_incomplete_type_error (r, rtype);
 			      TREE_TYPE (r) = error_mark_node;
 			    }

gcc/cp/typeck.c

@@ -112,7 +112,7 @@ complete_type (tree type)
 
   if (type == error_mark_node || COMPLETE_TYPE_P (type))
     ;
-  else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
+  else if (TREE_CODE (type) == ARRAY_TYPE)
     {
       tree t = complete_type (TREE_TYPE (type));
       unsigned int needs_constructing, has_nontrivial_dtor;

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2016-05-24  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/71147
+	* g++.dg/ext/flexary16.C: New test.
+
 2016-05-24  Ilya Verbin  <ilya.verbin@intel.com>
 
 	* gcc.target/i386/avx-ceil-sfix-2-vec.c: Define __NO_MATH_INLINES before

gcc/testsuite/g++.dg/ext/flexary16.C

@@ -0,0 +1,37 @@
+// PR c++/71147 - [6 Regression] Flexible array member wrongly rejected
+//   in template
+// { dg-do compile }
+
+template <typename>
+struct container
+{
+  struct elem {
+    unsigned u;
+  };
+
+  struct incomplete {
+    int x;
+    elem array[];
+  };
+};
+
+unsigned f (container<void>::incomplete* i)
+{
+  return i->array [0].u;
+}
+
+
+template <typename T>
+struct D: container<T>
+{
+  struct S {
+    int x;
+    typename container<T>::elem array[];
+  };
+};
+
+
+unsigned g (D<void>::S *s)
+{
+  return s->array [0].u;
+}

gcc/tree.h

@@ -4753,6 +4753,17 @@ ptrofftype_p (tree type)
 	  && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (sizetype));
 }
 
+/* Return true if the argument is a complete type or an array
+   of unknown bound (whose type is incomplete but) whose elements
+   have complete type.  */
+static inline bool
+complete_or_array_type_p (const_tree type)
+{
+  return COMPLETE_TYPE_P (type)
+         || (TREE_CODE (type) == ARRAY_TYPE
+	     && COMPLETE_TYPE_P (TREE_TYPE (type)));
+}
+
 extern tree strip_float_extensions (tree);
 extern int really_constant_p (const_tree);
 extern bool decl_address_invariant_p (const_tree);