Hi!
We use incorrect type for the NULL return value, the builtin is
char *strpbrk (const char *, const char *), so the first argument
is cast to const char * and we return (const char *) 0, while we
really should return (char *) 0. fold_builtin_n then adds:
ret = build1 (NOP_EXPR, TREE_TYPE (ret), ret);
SET_EXPR_LOCATION (ret, loc);
TREE_NO_WARNING (ret) = 1;
and thus we in the end have (char *) (_Literal (const char *) 0).
This bug then results in a -Wdiscarded-qualifiers warning.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2018-03-20 Jakub Jelinek <ja...@redhat.com>
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.
--- gcc/builtins.c.jj 2018-03-07 22:51:58.871478732 +0100
+++ gcc/builtins.c 2018-03-19 18:49:45.313898848 +0100
@@ -9573,7 +9573,7 @@ fold_builtin_strpbrk (location_t loc, tr
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/gcc.dg/pr84953.c.jj 2018-03-19 18:52:48.295893571 +0100
+++ gcc/testsuite/gcc.dg/pr84953.c 2018-03-19 18:52:31.935894043 +0100
@@ -0,0 +1,11 @@
+/* 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;
+}
Jakub
