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lint: add enum flags to the test about strict boolean mode

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This commit is contained in:
rillig 2021-01-10 21:45:50 +00:00
parent 465f117622
commit e9d1e169d3
1 changed files with 33 additions and 2 deletions
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35
tests/usr.bin/xlint/lint1/d_c99_bool_strict.c
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@ -1,4 +1,4 @@
/* $NetBSD: d_c99_bool_strict.c,v 1.1 2021/01/10 17:43:46 rillig Exp $ */
/* $NetBSD: d_c99_bool_strict.c,v 1.2 2021/01/10 21:45:50 rillig Exp $ */
# 3 "d_c99_bool_strict.c"
/*
@ -23,7 +23,7 @@
* its main operator is _Bool.
*/
// Not yet implemented: /* lint1-extra-flags: -B */
// Not yet implemented: /* lint1-extra-flags: -T */
/*
* The header <stdbool.h> defines the macros bool = _Bool, false = 0 and
@ -250,3 +250,34 @@ enum SB006_bool_constant_expression {
LOGAND = 0 && 1, /* ok */
};
enum BitSet {
ONE = 1 << 0,
TWO = 1 << 1,
FOUR = 1 << 2
};
/*
* It is debatable whether it is a good idea to allow expressions like these
* for _Bool. The strict rules above ensure that the code works in the same
* way whether or not the special rule C99 6.3.1.2 is active or not.
*
* If the code were to switch away from the C99 bool type to an ordinary
* unsigned integer type, the behavior might silently change. Because the
* rule C99 6.3.1.2 is no longer active in that case, high bits of the enum
* constant may get lost, thus evaluating to false even though a bit is set.
*
* It's probably better to not allow this kind of expressions, even though
* it may be popular, especially in usr.bin/make.
*/
int
S007_allow_flag_test_on_bit_set_enums(enum BitSet bs)
{
if (bs & ONE)
return 1;
if (!(bs & TWO))
return 2;
if (bs & FOUR)
return 2;
return 4;
}