[src/trunk]: src/usr.bin/xlint/lint1 lint: extend check for unconst functions

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/761a71733184
branches:  trunk
changeset: 1022951:761a71733184
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Aug 15 14:26:39 2021 +0000

description:
lint: extend check for unconst functions

The functions memchr, strpbrk, strrchr and strstr effectively remove the
const qualifier of their first argument, just like strchr.

diffstat:

 tests/usr.bin/xlint/lint1/msg_346.c   |  10 ++--
 tests/usr.bin/xlint/lint1/msg_346.exp |   4 ++
 usr.bin/xlint/lint1/tree.c            |  59 ++++++++++++++++++++++++----------
 3 files changed, 50 insertions(+), 23 deletions(-)

diffs (142 lines):

diff -r b70c98430fad -r 761a71733184 tests/usr.bin/xlint/lint1/msg_346.c
--- a/tests/usr.bin/xlint/lint1/msg_346.c       Sun Aug 15 14:00:27 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_346.c       Sun Aug 15 14:26:39 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msg_346.c,v 1.2 2021/08/15 14:00:27 rillig Exp $       */
+/*     $NetBSD: msg_346.c,v 1.3 2021/08/15 14:26:39 rillig Exp $       */
 # 3 "msg_346.c"
 
 // Test for message: call to '%s' effectively discards 'const' from argument [346]
@@ -40,14 +40,14 @@
 void
 all_functions(void)
 {
-       /* TODO: expect+1: warning: call to 'memchr' effectively discards 'const' from argument [346] */
+       /* expect+1: warning: call to 'memchr' effectively discards 'const' from argument [346] */
        take_char_ptr(memchr("string", 'c', 7));
        /* expect+1: warning: call to 'strchr' effectively discards 'const' from argument [346] */
        take_char_ptr(strchr("string", 'c'));
-       /* TODO: expect+1: warning: call to 'strpbrk' effectively discards 'const' from argument [346] */
+       /* expect+1: warning: call to 'strpbrk' effectively discards 'const' from argument [346] */
        take_char_ptr(strpbrk("string", "c"));
-       /* TODO: expect+1: warning: call to 'strrchr' effectively discards 'const' from argument [346] */
+       /* expect+1: warning: call to 'strrchr' effectively discards 'const' from argument [346] */
        take_char_ptr(strrchr("string", 'c'));
-       /* TODO: expect+1: warning: call to 'strstr' effectively discards 'const' from argument [346] */
+       /* expect+1: warning: call to 'strstr' effectively discards 'const' from argument [346] */
        take_char_ptr(strstr("string", "c"));
 }
diff -r b70c98430fad -r 761a71733184 tests/usr.bin/xlint/lint1/msg_346.exp
--- a/tests/usr.bin/xlint/lint1/msg_346.exp     Sun Aug 15 14:00:27 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_346.exp     Sun Aug 15 14:26:39 2021 +0000
@@ -1,4 +1,8 @@
 msg_346.c(26): warning: call to 'strchr' effectively discards 'const' from argument [346]
 msg_346.c(32): warning: call to 'strchr' effectively discards 'const' from argument [346]
 msg_346.c(37): warning: call to 'strchr' effectively discards 'const' from argument [346]
+msg_346.c(44): warning: call to 'memchr' effectively discards 'const' from argument [346]
 msg_346.c(46): warning: call to 'strchr' effectively discards 'const' from argument [346]
+msg_346.c(48): warning: call to 'strpbrk' effectively discards 'const' from argument [346]
+msg_346.c(50): warning: call to 'strrchr' effectively discards 'const' from argument [346]
+msg_346.c(52): warning: call to 'strstr' effectively discards 'const' from argument [346]
diff -r b70c98430fad -r 761a71733184 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Sun Aug 15 14:00:27 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Sun Aug 15 14:26:39 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.335 2021/08/15 13:08:19 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.336 2021/08/15 14:26:39 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.335 2021/08/15 13:08:19 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.336 2021/08/15 14:26:39 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -1349,12 +1349,27 @@
 }
 
 static bool
-is_direct_function_call(const tnode_t *tn, const char *name)
+is_direct_function_call(const tnode_t *tn, const char **out_name)
 {
-       return tn->tn_op == CALL &&
-              tn->tn_left->tn_op == ADDR &&
-              tn->tn_left->tn_left->tn_op == NAME &&
-              strcmp(tn->tn_left->tn_left->tn_sym->s_name, name) == 0;
+
+       if (!(tn->tn_op == CALL &&
+             tn->tn_left->tn_op == ADDR &&
+             tn->tn_left->tn_left->tn_op == NAME))
+               return false;
+
+       *out_name = tn->tn_left->tn_left->tn_sym->s_name;
+       return true;
+}
+
+static bool
+is_unconst_function(const char *name)
+{
+
+       return strcmp(name, "memchr") == 0 ||
+              strcmp(name, "strchr") == 0 ||
+              strcmp(name, "strpbrk") == 0 ||
+              strcmp(name, "strrchr") == 0 ||
+              strcmp(name, "strstr") == 0;
 }
 
 static bool
@@ -1385,23 +1400,31 @@
 }
 
 static bool
-is_strchr_arg_const(const tnode_t *tn)
+is_first_arg_const(const tnode_t *tn)
 {
-       return tn->tn_right->tn_op == PUSH &&
-              tn->tn_right->tn_right->tn_op == PUSH &&
-              tn->tn_right->tn_right->tn_right == NULL &&
-              is_const_char_pointer(tn->tn_right->tn_right->tn_left);
+       const tnode_t *an;
+
+       an = tn->tn_right;
+       if (an == NULL)
+               return false;
+
+       while (an->tn_right != NULL)
+               an = an->tn_right;
+       return is_const_char_pointer(an->tn_left);
 }
 
 static void
-check_unconst_strchr(const type_t *lstp,
-                    const tnode_t *rn, const type_t *rstp)
+check_unconst_function(const type_t *lstp,
+                      const tnode_t *rn, const type_t *rstp)
 {
+       const char *function_name;
+
        if (lstp->t_tspec == CHAR && !lstp->t_const &&
-           is_direct_function_call(rn, "strchr") &&
-           is_strchr_arg_const(rn)) {
+           is_direct_function_call(rn, &function_name) &&
+           is_unconst_function(function_name) &&
+           is_first_arg_const(rn)) {
                /* call to '%s' effectively discards 'const' from argument */
-               warning(346, "strchr");
+               warning(346, function_name);
        }
 }
 
@@ -1490,7 +1513,7 @@
                }
 
                if (!tflag)
-                       check_unconst_strchr(lstp, rn, rstp);
+                       check_unconst_function(lstp, rn, rstp);
 
                return true;
        }