re PR c/71719 (invalid set-but-not-used warning with vectors)

	PR c/71719
	* c-typeck.c (mark_exp_read): Handle VIEW_CONVERT_EXPR.

	* c-c++-common/Wunused-var-15.c: New test.

From-SVN: r237937

gcc/c/ChangeLog

+2016-07-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/71719
+	* c-typeck.c (mark_exp_read): Handle VIEW_CONVERT_EXPR.
+
 2016-06-29  Thomas Schwinge  <thomas@codesourcery.com>
 
 	* c-parser.c (c_parser_pragma) <PRAGMA_OMP_CANCELLATION_POINT>:

gcc/c/c-typeck.c

@@ -1896,6 +1896,7 @@ mark_exp_read (tree exp)
     case IMAGPART_EXPR:
     CASE_CONVERT:
     case ADDR_EXPR:
+    case VIEW_CONVERT_EXPR:
       mark_exp_read (TREE_OPERAND (exp, 0));
       break;
     case COMPOUND_EXPR:

gcc/testsuite/ChangeLog

+2016-07-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/71719
+	* c-c++-common/Wunused-var-15.c: New test.
+
 2016-07-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR fortran/71687

gcc/testsuite/c-c++-common/Wunused-var-15.c

+/* PR c/71719 */
+/* { dg-do compile } */
+/* { dg-options "-Wunused -W -Wno-psabi" } */
+
+typedef unsigned V __attribute__ ((vector_size (16)));
+
+void bar (unsigned);
+
+V x;
+
+void
+foo (V v)	/* { dg-bogus "set but not used" } */
+{
+  bar (v[0]);
+  V w = x;	/* { dg-bogus "set but not used" } */
+  bar (w[1]);
+}
+
+/* Ignore a warning that is irrelevant to the purpose of this test.  */
+/* { dg-prune-output ".*GCC vector passed by reference.*" } */