[src/trunk]: src/usr.bin/xlint/lint1 lint: fix assertion failure when promoti...

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

details:   https://anonhg.NetBSD.org/src/rev/03af1b41a938
branches:  trunk
changeset: 379010:03af1b41a938
user:      rillig <rillig%NetBSD.org@localhost>
date:      Tue May 04 05:40:10 2021 +0000

description:
lint: fix assertion failure when promoting a bit-field larger than int

diffstat:

 tests/usr.bin/xlint/lint1/gcc_bit_field_types.c |   5 ++---
 usr.bin/xlint/lint1/tree.c                      |  23 ++++++++++-------------
 2 files changed, 12 insertions(+), 16 deletions(-)

diffs (65 lines):

diff -r 5908bf93ca20 -r 03af1b41a938 tests/usr.bin/xlint/lint1/gcc_bit_field_types.c
--- a/tests/usr.bin/xlint/lint1/gcc_bit_field_types.c   Tue May 04 05:32:52 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/gcc_bit_field_types.c   Tue May 04 05:40:10 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: gcc_bit_field_types.c,v 1.4 2021/05/04 05:32:52 rillig Exp $   */
+/*     $NetBSD: gcc_bit_field_types.c,v 1.5 2021/05/04 05:40:10 rillig Exp $   */
 # 3 "gcc_bit_field_types.c"
 
 /*
@@ -32,6 +32,5 @@ promote_large_bit_field(struct large_bit
         * lint: assertion "len == size_in_bits(INT)" failed
         *     in promote at tree.c:1698
         */
-       /* TODO: remove the cast since it hides an assertion failure */
-       return (unsigned long long)lbf.member & 0xf;
+       return lbf.member & 0xf;
 }
diff -r 5908bf93ca20 -r 03af1b41a938 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Tue May 04 05:32:52 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Tue May 04 05:40:10 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.280 2021/04/18 17:54:33 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.281 2021/05/04 05:40:10 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 1.280 2021/04/18 17:54:33 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.281 2021/05/04 05:40:10 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -1686,21 +1686,18 @@ promote(op_t op, bool farg, tnode_t *tn)
 
        if (!tflag) {
                /*
-                * ANSI C requires that the result is always of type INT
-                * if INT can represent all possible values of the previous
-                * type.
+                * C99 6.3.1.1p2 requires for types with lower rank than int
+                * that "If an int can represent all the values of the
+                * original type, the value is converted to an int; otherwise
+                * it is converted to an unsigned int", and that "All other
+                * types are unchanged by the integer promotions".
                 */
                if (tn->tn_type->t_bitfield) {
                        len = tn->tn_type->t_flen;
-                       if (size_in_bits(INT) > len) {
+                       if (len < size_in_bits(INT)) {
                                t = INT;
-                       } else {
-                               lint_assert(len == size_in_bits(INT));
-                               if (is_uinteger(t)) {
-                                       t = UINT;
-                               } else {
-                                       t = INT;
-                               }
+                       } else if (len == size_in_bits(INT)) {
+                               t = is_uinteger(t) ? UINT : INT;
                        }
                } else if (t == CHAR || t == UCHAR || t == SCHAR) {
                        t = (size_in_bits(CHAR) < size_in_bits(INT)