re PR c++/87148 (backward compatibility issue to take char [] as incomplete type)

	PR c++/87148
	* init.c (build_value_init_noctor): Ignore flexible array members.

	* g++.dg/ext/flexary34.C: New test.

From-SVN: r269434

gcc/cp/ChangeLog

+2019-03-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/87148
+	* init.c (build_value_init_noctor): Ignore flexible array members.
+
 2019-03-06  Jason Merrill  <jason@redhat.com>
 
 	PR c++/89576 - if constexpr of lambda capture.

gcc/cp/init.c

@@ -419,6 +419,15 @@ build_value_init_noctor (tree type, tsubst_flags_t complain)
 	      if (ftype == error_mark_node)
 		continue;
 
+	      /* Ignore flexible array members for value initialization.  */
+	      if (TREE_CODE (ftype) == ARRAY_TYPE
+		  && !COMPLETE_TYPE_P (ftype)
+		  && !TYPE_DOMAIN (ftype)
+		  && COMPLETE_TYPE_P (TREE_TYPE (ftype))
+		  && (next_initializable_field (DECL_CHAIN (field))
+		      == NULL_TREE))
+		continue;
+
 	      /* We could skip vfields and fields of types with
 		 user-defined constructors, but I think that won't improve
 		 performance at all; it should be simpler in general just

gcc/testsuite/ChangeLog

+2019-03-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/87148
+	* g++.dg/ext/flexary34.C: New test.
+
 2019-03-06  Peter Bergner  <bergner@linux.ibm.com>
 
 	PR rtl-optimization/88845

gcc/testsuite/g++.dg/ext/flexary34.C

+// PR c++/87148
+// { dg-do compile }
+// { dg-options "-pedantic" }
+
+struct Tst { int i; char t[]; };	// { dg-warning "forbids flexible array member" }
+
+Tst t {};				// { dg-warning "extended initializer lists only available with" "" { target c++98_only } }
+Tst u = Tst();
+void foo () { Tst u = {}; }
+Tst *bar () { return new Tst (); }