[src/trunk]: src/usr.bin/xlint/lint1 lint: don't warn about negative '>>' whe...

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

details:   https://anonhg.NetBSD.org/src/rev/59e9403263e9
branches:  trunk
changeset: 373284:59e9403263e9
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Jan 29 17:13:10 2023 +0000

description:
lint: don't warn about negative '>>' when the actual value is positive

diffstat:

 tests/usr.bin/xlint/lint1/msg_117.c |  9 +++++----
 usr.bin/xlint/lint1/tree.c          |  8 ++++++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diffs (52 lines):

diff -r c93b5f3146ec -r 59e9403263e9 tests/usr.bin/xlint/lint1/msg_117.c
--- a/tests/usr.bin/xlint/lint1/msg_117.c       Sun Jan 29 17:02:09 2023 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_117.c       Sun Jan 29 17:13:10 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msg_117.c,v 1.12 2023/01/29 17:02:09 rillig Exp $      */
+/*     $NetBSD: msg_117.c,v 1.13 2023/01/29 17:13:10 rillig Exp $      */
 # 3 "msg_117.c"
 
 // Test for message: bitwise '%s' on signed value possibly nonportable [117]
@@ -139,9 +139,10 @@
        if (((x >> 31) & 2) != 0)
                return;
 
-       /* The result of '&' is guaranteed to be positive. */
-       /* XXX: Don't warn here. */
-       /* expect+1: warning: bitwise '>>' on signed value possibly nonportable [117] */
+       /*
+        * The result of '&' is guaranteed to be positive, so don't warn.
+        * Code like this typically occurs in hexdump functions.
+        */
        if ((x & 0xf0) >> 4 != 0)
                return;
 }
diff -r c93b5f3146ec -r 59e9403263e9 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Sun Jan 29 17:02:09 2023 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Sun Jan 29 17:13:10 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.501 2023/01/29 13:57:35 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.502 2023/01/29 17:13:10 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID)
-__RCSID("$NetBSD: tree.c,v 1.501 2023/01/29 13:57:35 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.502 2023/01/29 17:13:10 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -1161,6 +1161,10 @@
 
        /* operands have integer types (checked in typeok) */
        if (pflag && !is_uinteger(olt)) {
+               integer_constraints lc = ic_expr(ln);
+               if (!ic_maybe_signed(ln->tn_type, &lc))
+                       return;
+
                /*
                 * The left operand is signed. This means that
                 * the operation is (possibly) nonportable.