[src/trunk]: src/usr.bin/xlint/lint1 tests/lint: demonstrate bugs in anonymou...

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

details:   https://anonhg.NetBSD.org/src/rev/e2c0efba9f5b
branches:  trunk
changeset: 377179:e2c0efba9f5b
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Jun 30 07:18:02 2023 +0000

description:
tests/lint: demonstrate bugs in anonymous struct/union handling

diffstat:

 tests/usr.bin/xlint/lint1/expr_sizeof.c |  42 ++++++++++++++++++++++++++++++++-
 usr.bin/xlint/lint1/decl.c              |   6 +++-
 2 files changed, 45 insertions(+), 3 deletions(-)

diffs (85 lines):

diff -r 8ad59c199b21 -r e2c0efba9f5b tests/usr.bin/xlint/lint1/expr_sizeof.c
--- a/tests/usr.bin/xlint/lint1/expr_sizeof.c   Fri Jun 30 02:03:58 2023 +0000
+++ b/tests/usr.bin/xlint/lint1/expr_sizeof.c   Fri Jun 30 07:18:02 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: expr_sizeof.c,v 1.6 2023/06/28 21:41:27 rillig Exp $   */
+/*     $NetBSD: expr_sizeof.c,v 1.7 2023/06/30 07:18:02 rillig Exp $   */
 # 3 "expr_sizeof.c"
 
 /*
@@ -74,6 +74,46 @@ variable_length_array(int n)
        typedef int sizeof_local_arr[-(int)sizeof(local_arr)];
 }
 
+void
+bit_fields(void)
+{
+       struct {
+               _Bool flag0:1;
+               _Bool flag1:1;
+               _Bool flag2:1;
+       } flags;
+       /* expect+1: error: negative array dimension (-1) [20] */
+       typedef int sizeof_flags[-(int)sizeof(flags)];
+
+       struct {
+               struct {
+                       _Bool flag0:1;
+                       _Bool flag1:1;
+                       _Bool flag2:1;
+               };
+       } anonymous_flags;
+       /* FIXME: sizeof must be 1, not 0. */
+       typedef int sizeof_anonymous_flags[-(int)sizeof(anonymous_flags)];
+
+       struct {
+               unsigned int bits0:16;
+               unsigned int bits1:16;
+       } same_storage_unit;
+       /* expect+1: error: negative array dimension (-4) [20] */
+       typedef int sizeof_same_storage_unit[-(int)sizeof(same_storage_unit)];
+
+       // Detect whether a bit-field can span multiple storage units.
+       // If so, the size is 12, if not, the size is 16.
+       struct {
+               unsigned int bits0:24;
+               unsigned int bits1:24;
+               unsigned int bits2:24;
+               unsigned int bits3:24;
+       } cross_storage_unit;
+       /* expect+1: error: negative array dimension (-16) [20] */
+       typedef int sizeof_cross_storage_unit[-(int)sizeof(cross_storage_unit)];
+}
+
 /*
  * Ensure that anonymous structs and unions are handled correctly.  They were
  * added in C11, and lint did not properly support them until 2023.
diff -r 8ad59c199b21 -r e2c0efba9f5b usr.bin/xlint/lint1/decl.c
--- a/usr.bin/xlint/lint1/decl.c        Fri Jun 30 02:03:58 2023 +0000
+++ b/usr.bin/xlint/lint1/decl.c        Fri Jun 30 07:18:02 2023 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: decl.c,v 1.323 2023/06/29 22:52:44 rillig Exp $ */
+/* $NetBSD: decl.c,v 1.324 2023/06/30 07:18:02 rillig Exp $ */
 
 /*
  * Copyright (c) 1996 Christopher G. Demetriou.  All Rights Reserved.
@@ -38,7 +38,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID)
-__RCSID("$NetBSD: decl.c,v 1.323 2023/06/29 22:52:44 rillig Exp $");
+__RCSID("$NetBSD: decl.c,v 1.324 2023/06/30 07:18:02 rillig Exp $");
 #endif
 
 #include <sys/param.h>
@@ -463,8 +463,10 @@ bit_field_width(sym_t **mem)
                width += (*mem)->s_type->t_bit_field_width;
                *mem = (*mem)->s_next;
        }
+
        // XXX: Why INT_SIZE? C99 6.7.2.1p4 allows bit-fields to have type
        // XXX: _Bool or another implementation-defined type.
+       // XXX: Why round down instead of up? See expr_sizeof.c, anonymous_flags.
        return width - width % INT_SIZE;
 }