[src/trunk]: src/usr.bin/xlint/lint1 lint: don't warn about constant conditio...

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

details:   https://anonhg.NetBSD.org/src/rev/554e3d4db042
branches:  trunk
changeset: 950797:554e3d4db042
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Jan 31 12:44:34 2021 +0000

description:
lint: don't warn about constant condition in 'do { } while (0)'

diffstat:

 tests/usr.bin/xlint/lint1/msg_161.c   |   6 +++---
 tests/usr.bin/xlint/lint1/msg_161.exp |   1 -
 usr.bin/xlint/lint1/cgram.y           |   8 ++++----
 usr.bin/xlint/lint1/externs1.h        |   4 ++--
 usr.bin/xlint/lint1/func.c            |  20 ++++++++++----------
 usr.bin/xlint/lint1/init.c            |   8 ++++----
 usr.bin/xlint/lint1/tree.c            |  10 ++++++----
 7 files changed, 29 insertions(+), 28 deletions(-)

diffs (250 lines):

diff -r 52350e29a3b6 -r 554e3d4db042 tests/usr.bin/xlint/lint1/msg_161.c
--- a/tests/usr.bin/xlint/lint1/msg_161.c       Sun Jan 31 12:30:53 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_161.c       Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msg_161.c,v 1.3 2021/01/31 12:30:53 rillig Exp $       */
+/*     $NetBSD: msg_161.c,v 1.4 2021/01/31 12:44:34 rillig Exp $       */
 # 3 "msg_161.c"
 
 // Test for message: constant in conditional context [161]
@@ -23,14 +23,14 @@
  * The pattern 'do { } while (0)' is a common technique to define a
  * preprocessor macro that behaves like a single statement.  There is
  * nothing unusual or surprising about the constant condition.
- * Still, lint warns about it. FIXME don't.
+ * Before tree.c 1.202 from 2021-01-31, lint warned about it.
  */
 void
 do_while_0(void)
 {
        do {
 
-       } while (0);            /* expect: 161 */
+       } while (0);
 }
 
 void
diff -r 52350e29a3b6 -r 554e3d4db042 tests/usr.bin/xlint/lint1/msg_161.exp
--- a/tests/usr.bin/xlint/lint1/msg_161.exp     Sun Jan 31 12:30:53 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_161.exp     Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,3 @@
 msg_161.c(11): warning: constant in conditional context [161]
 msg_161.c(18): warning: constant in conditional context [161]
-msg_161.c(33): warning: constant in conditional context [161]
 msg_161.c(41): warning: constant in conditional context [161]
diff -r 52350e29a3b6 -r 554e3d4db042 usr.bin/xlint/lint1/cgram.y
--- a/usr.bin/xlint/lint1/cgram.y       Sun Jan 31 12:30:53 2021 +0000
+++ b/usr.bin/xlint/lint1/cgram.y       Sun Jan 31 12:44:34 2021 +0000
@@ -1,5 +1,5 @@
 %{
-/* $NetBSD: cgram.y,v 1.159 2021/01/31 11:23:01 rillig Exp $ */
+/* $NetBSD: cgram.y,v 1.160 2021/01/31 12:44:34 rillig Exp $ */
 
 /*
  * Copyright (c) 1996 Christopher G. Demetriou.  All Rights Reserved.
@@ -35,7 +35,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: cgram.y,v 1.159 2021/01/31 11:23:01 rillig Exp $");
+__RCSID("$NetBSD: cgram.y,v 1.160 2021/01/31 12:44:34 rillig Exp $");
 #endif
 
 #include <limits.h>
@@ -1557,7 +1557,7 @@
 
 expr_statement:
          expr T_SEMI {
-               expr($1, 0, 0, 0);
+               expr($1, false, false, false, false);
                ftflg = false;
          }
        | T_SEMI {
@@ -1576,7 +1576,7 @@
                if ($1->tn_op == NAME)
                        $1->tn_sym->s_used = true;
                $$ = $1;
-               expr($1, 0, 0, 0);
+               expr($1, false, false, false, false);
                ftflg = false;
          }
        | non_expr_statement {
diff -r 52350e29a3b6 -r 554e3d4db042 usr.bin/xlint/lint1/externs1.h
--- a/usr.bin/xlint/lint1/externs1.h    Sun Jan 31 12:30:53 2021 +0000
+++ b/usr.bin/xlint/lint1/externs1.h    Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: externs1.h,v 1.64 2021/01/30 18:16:45 rillig Exp $     */
+/*     $NetBSD: externs1.h,v 1.65 2021/01/31 12:44:34 rillig Exp $     */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -216,7 +216,7 @@
 extern tnode_t *new_function_argument_node(tnode_t *, tnode_t *);
 extern tnode_t *new_function_call_node(tnode_t *, tnode_t *);
 extern val_t   *constant(tnode_t *, bool);
-extern void    expr(tnode_t *, bool, bool, bool);
+extern void    expr(tnode_t *, bool, bool, bool, bool);
 extern void    check_expr_misc(const tnode_t *, bool, bool, bool,
                    bool, bool, bool);
 extern bool    constant_addr(tnode_t *, sym_t **, ptrdiff_t *);
diff -r 52350e29a3b6 -r 554e3d4db042 usr.bin/xlint/lint1/func.c
--- a/usr.bin/xlint/lint1/func.c        Sun Jan 31 12:30:53 2021 +0000
+++ b/usr.bin/xlint/lint1/func.c        Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: func.c,v 1.66 2021/01/30 18:16:45 rillig Exp $ */
+/*     $NetBSD: func.c,v 1.67 2021/01/31 12:44:34 rillig Exp $ */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: func.c,v 1.66 2021/01/30 18:16:45 rillig Exp $");
+__RCSID("$NetBSD: func.c,v 1.67 2021/01/31 12:44:34 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -569,7 +569,7 @@
        if (tn != NULL)
                tn = check_controlling_expression(tn);
        if (tn != NULL)
-               expr(tn, false, true, false);
+               expr(tn, false, true, false, false);
        pushctrl(T_IF);
 }
 
@@ -642,7 +642,7 @@
                tp->t_tspec = INT;
        }
 
-       expr(tn, true, false, true);
+       expr(tn, true, false, true, false);
 
        pushctrl(T_SWITCH);
        cstmt->c_switch = true;
@@ -726,7 +726,7 @@
        if (tn != NULL && tn->tn_op == CON)
                cstmt->c_infinite = is_nonzero(tn);
 
-       expr(tn, false, true, true);
+       expr(tn, false, true, true, false);
 }
 
 /*
@@ -789,7 +789,7 @@
                        error(323);
        }
 
-       expr(tn, false, true, true);
+       expr(tn, false, true, true, true);
 
        /*
         * The end of the loop is only reached if it is no endless loop
@@ -832,12 +832,12 @@
        cstmt->c_cfpos = csrc_pos;
 
        if (tn1 != NULL)
-               expr(tn1, false, false, true);
+               expr(tn1, false, false, true, false);
 
        if (tn2 != NULL)
                tn2 = check_controlling_expression(tn2);
        if (tn2 != NULL)
-               expr(tn2, false, true, true);
+               expr(tn2, false, true, true, false);
 
        cstmt->c_infinite =
            tn2 == NULL || (tn2->tn_op == CON && is_nonzero(tn2));
@@ -877,7 +877,7 @@
        }
 
        if (tn3 != NULL) {
-               expr(tn3, false, false, true);
+               expr(tn3, false, false, true, false);
        } else {
                tfreeblk();
        }
@@ -1013,7 +1013,7 @@
                        }
                }
 
-               expr(tn, true, false, true);
+               expr(tn, true, false, true, false);
 
        } else {
 
diff -r 52350e29a3b6 -r 554e3d4db042 usr.bin/xlint/lint1/init.c
--- a/usr.bin/xlint/lint1/init.c        Sun Jan 31 12:30:53 2021 +0000
+++ b/usr.bin/xlint/lint1/init.c        Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: init.c,v 1.65 2021/01/30 18:16:45 rillig Exp $ */
+/*     $NetBSD: init.c,v 1.66 2021/01/31 12:44:34 rillig Exp $ */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: init.c,v 1.65 2021/01/30 18:16:45 rillig Exp $");
+__RCSID("$NetBSD: init.c,v 1.66 2021/01/31 12:44:34 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -584,7 +584,7 @@
                ln->tn_type = tduptyp(ln->tn_type);
                ln->tn_type->t_const = false;
                tn = build(ASSIGN, ln, tn);
-               expr(tn, false, false, false);
+               expr(tn, false, false, false, false);
                return;
        }
 
@@ -628,7 +628,7 @@
         * expr() would free it.
         */
        tmem = tsave();
-       expr(tn, true, false, true);
+       expr(tn, true, false, true, false);
        trestor(tmem);
 
        if (is_integer(lt) && ln->tn_type->t_bitfield && !is_integer(rt)) {
diff -r 52350e29a3b6 -r 554e3d4db042 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Sun Jan 31 12:30:53 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Sun Jan 31 12:44:34 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.201 2021/01/31 12:20:00 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.202 2021/01/31 12:44:34 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 1.201 2021/01/31 12:20:00 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.202 2021/01/31 12:44:34 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -3730,7 +3730,7 @@
  * for the expression.
  */
 void
-expr(tnode_t *tn, bool vctx, bool tctx, bool dofreeblk)
+expr(tnode_t *tn, bool vctx, bool tctx, bool dofreeblk, bool constcond_zero_ok)
 {
 
        lint_assert(tn != NULL || nerr != 0);
@@ -3750,7 +3750,9 @@
                        /* assignment in conditional context */
                        warning(159);
        } else if (tn->tn_op == CON) {
-               if (hflag && tctx && !constcond_flag)
+               if (hflag && tctx && !constcond_flag &&
+                   !(constcond_zero_ok &&
+                     is_int_constant_zero(tn, tn->tn_type->t_tspec)))
                        /* constant in conditional context */
                        warning(161);
        }