Hello!
The current sparse has problems with the -Wtypesign flag. If causes
bogus warnings. Take for example following test.c:
static unsigned char foobar(void);
static unsigned char foobar(void)
{
return 0;
}
$ sparse -Wtypesign test.c
test.c:2:22: error: symbol 'foobar' redeclared with different type
(originally declared at test.c:1) - different signedness
Debugging shows that the function definition doesn't have the
signed/unsigned modifiers, unlike the function declaration:
2412 typediff = type_difference(sym, next, 0, 0);
(gdb) p/ sym->ctype.modifiers
$1 = 0x800004
(gdb) p/ next->ctype.modifiers
$2 = 0x800084
0x80 is MOD_UNSIGNED.
The signedness modifiers are set in evaluate_symbol(), which hasn't been
called for sym yet. I have devised following patch, that appears to fix
the problem:
---
Fix -Wtypesign
Run evaluate_symbol() before check_duplicates() so that the signedness
of the token is known by the time the token is compared with other
tokens.
Signed-off-by: Pavel Roskin <proski@xxxxxxx>
---
evaluate.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/evaluate.c b/evaluate.c
index 42005eb..2561f38 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2473,8 +2473,8 @@ void evaluate_symbol_list(struct symbol_
struct symbol *sym;
FOR_EACH_PTR(list, sym) {
- check_duplicates(sym);
evaluate_symbol(sym);
+ check_duplicates(sym);
} END_FOR_EACH_PTR(sym);
}
I tested -Wtypesign on some Linux drivers. It found some real sign
mismatches and no bogus warnings.
Still, I haven't seen sparse code until today, so the patch should be
evaluated carefully.
--
Regards,
Pavel Roskin
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