Fix spurious warning for strstr (s, "").

* builtins.c (fold_builtin_strstr): Pass s1 through fold_convert before
returning it.
* gcc.dg/builtin-strstr.c: New.

From-SVN: r107206

gcc/ChangeLog

+2005-11-18  James E Wilson  <wilson@specifix.com>
+
+	* builtins.c (fold_builtin_strstr): Pass s1 through fold_convert before
+	returning it.
+
 2005-11-18  Mike Stump  <mrs@apple.com>
 
 	* c-common.c (handle_cleanup_attribute): Use a lang hook for lookup_name.

gcc/builtins.c

@@ -9199,8 +9199,10 @@ fold_builtin_strstr (tree arglist, tree type)
 	  return fold_convert (type, tem);
 	}
 
+      /* The argument is const char *, and the result is char *, so we need
+	 a type conversion here to avoid a warning.  */
       if (p2[0] == '\0')
-	return s1;
+	return fold_convert (type, s1);
 
       if (p2[1] != '\0')
 	return 0;

gcc/testsuite/ChangeLog

+2005-11-18  James E Wilson  <wilson@specifix.com>
+
+	* gcc.dg/builtin-strstr.c: New.
+
 2005-11-18  Richard Henderson  <rth@redhat.com>
 
 	* gcc.target/ia64/20010423-1.c, gcc.target/ia64/20020313-1.c,

gcc/testsuite/gcc.dg/builtin-strstr.c

+/* The strstr call is expanded to just "s", which should not result in a
+   warning about discarding qualifiers in an assignment.  */
+/* { dg-do compile } */
+extern char * strstr (const char *s1, const char * s2);
+void foo(const char *s){
+  char * cp;
+  cp = strstr(s, "");
+}