re PR c/84953 (misleading warning from strpbrk(x,""))

	PR c/84953
	* builtins.c (fold_builtin_strpbrk): For strpbrk(x, "") use type
	instead of TREE_TYPE (s1) for the return value.

	* gcc.dg/pr84953.c: New test.

From-SVN: r258671

gcc/ChangeLog

+2018-03-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/84953
+	* builtins.c (fold_builtin_strpbrk): For strpbrk(x, "") use type
+	instead of TREE_TYPE (s1) for the return value.
+
 2018-03-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/84946

gcc/builtins.c

@@ -9573,7 +9573,7 @@ fold_builtin_strpbrk (location_t loc, tree s1, tree s2, tree type)
       if (p2[0] == '\0')
 	/* strpbrk(x, "") == NULL.
 	   Evaluate and ignore s1 in case it had side-effects.  */
-	return omit_one_operand_loc (loc, TREE_TYPE (s1), integer_zero_node, s1);
+	return omit_one_operand_loc (loc, type, integer_zero_node, s1);
 
       if (p2[1] != '\0')
 	return NULL_TREE;  /* Really call strpbrk.  */

gcc/testsuite/ChangeLog

+2018-03-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/84953
+	* gcc.dg/pr84953.c: New test.
+
 2018-03-19  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/84925

gcc/testsuite/gcc.dg/pr84953.c

+/* PR c/84953 */
+/* { dg-do compile } */
+
+char *strpbrk (const char *, const char *);
+
+char *
+test (char *p)
+{
+  p = strpbrk (p, "");	/* { dg-bogus "assignment discards 'const' qualifier from pointer target type" } */
+  return p;
+}