[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #19 from Marek Polacek mpolacek at gcc dot gnu.org --- Author: mpolacek Date: Fri Feb 27 14:11:53 2015 New Revision: 221061 URL: https://gcc.gnu.org/viewcvs?rev=221061root=gccview=rev Log: PR c/65040 * doc/invoke.texi: Update to reflect that -Wformat=2 doesn't enable -Wformat-signedness anymore. * c.opt (Wformat-signedness): Don't enable by -Wformat=2. * gcc.dg/pr65066.c: Use -Wformat -Wformat-signedness and not -Wformat=2. Modified: trunk/gcc/ChangeLog trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c.opt trunk/gcc/doc/invoke.texi trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/gcc.dg/pr65066.c
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Marek Polacek mpolacek at gcc dot gnu.org changed: What|Removed |Added Status|REOPENED|RESOLVED Resolution|--- |FIXED --- Comment #20 from Marek Polacek mpolacek at gcc dot gnu.org --- Closing.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #15 from Richard Biener rguenth at gcc dot gnu.org --- I'd also say that warnings for formats that do not have a signed form are useless, thus for %o, %x and %X. But I guess you beg to differ.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #18 from Richard Biener rguenth at gcc dot gnu.org --- And it was just mentioned that the diagnostic should print [-Wformat-signedness] not [-Wformat=] (or both)
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #16 from Marek Polacek mpolacek at gcc dot gnu.org --- Ok, I can fix the integer constant case as well. (In reply to Richard Biener from comment #15) I'd also say that warnings for formats that do not have a signed form are useless, thus for %o, %x and %X. But I guess you beg to differ. I don't know - it wasn't me who implemented this warning, I'm just doing it less verbose ;).
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040
Richard Biener rguenth at gcc dot gnu.org changed:
What|Removed |Added
Status|RESOLVED|REOPENED
Resolution|FIXED |---
--- Comment #14 from Richard Biener rguenth at gcc dot gnu.org ---
#include stdio.h
int main()
{
printf (%x%u\n, 4, 4);
}
gcc-5 -Wall t.c -Wformat=2
t.c: In function 'main':
t.c:4:11: warning: format '%x' expects argument of type 'unsigned int', but
argument 2 has type 'int' [-Wformat=]
printf (%x%u\n, 4, 4);
^
t.c:4:11: warning: format '%u' expects argument of type 'unsigned int', but
argument 3 has type 'int' [-Wformat=]
that's undesirable as well (the constant fits in an unsigned int).
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #17 from Jakub Jelinek jakub at gcc dot gnu.org --- IMHO the warning is completely useless, but perhaps some people disagree.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #13 from Marek Polacek mpolacek at gcc dot gnu.org --- Note that this patch had a followup: PR65066.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #10 from Marek Polacek mpolacek at gcc dot gnu.org --- That's because on your architecture char is signed by default. Try adding unsigned or using -funsigned-char and the warning should be gone.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040
--- Comment #9 from Jiri Slaby jirislaby at gmail dot com ---
What about this?
#include stdio.h
void x(char *ch)
{
printf(%x\n, ch[10]);
}
It still produces the warning. (I cannot reopen as I am not a reporter.)
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #12 from Jiri Slaby jirislaby at gmail dot com --- (In reply to Marek Polacek from comment #10) That's because on your architecture char is signed by default. Try adding unsigned or using -funsigned-char and the warning should be gone. Ok, I wanted to make sure, that the format string is really wrong here. It should be %hhx. Ouch, that will be pain to fix all those 400 bad format strings in grub2, given they use Werror WFormat :D.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #11 from Jakub Jelinek jakub at gcc dot gnu.org --- -funsigned-char is an option that shouldn't be used without serious consideration. That said, I think in that case the warning is intentional, you are indeed passing a signed value to unsigned format. If you don't care about that, don't use -Wformat=2 or use -Wno-format-signedness.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #4 from Jakub Jelinek jakub at gcc dot gnu.org --- (In reply to Marek Polacek from comment #2) Taking. I think check_format_types needs a small tweak to look thru NOP_EXPRs. Well, more like do some lame VR computation and not warn if the signedness doesn't really matter.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040
Mark Wielaard mark at gcc dot gnu.org changed:
What|Removed |Added
CC||mark at gcc dot gnu.org
--- Comment #5 from Mark Wielaard mark at gcc dot gnu.org ---
Note that this also triggers for code that looks just fine to the user:
#include stdio.h
#include inttypes.h
int
main (int argc, char **argv)
{
uint8_t u = 16;
printf (u = %02 PRIx8 \n, u);
return 0;
}
m.c: In function ‘main’:
m.c:8:11: warning: format ‘%x’ expects argument of type ‘unsigned int’, but
argument 2 has type ‘int’ [-Wformat=]
printf (u = %02 PRIx8 \n, u);
^
Which is somewhat surprising since the user explicitly matched the type and
format specifier.
This is caused by the definition of the PRIx format specifiers all mapping back
to x in inttypes.h
/* lowercase hexadecimal notation. */
# define PRIx8 x
# define PRIx16 x
# define PRIx32 x
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Marek Polacek mpolacek at gcc dot gnu.org changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org --- Comment #2 from Marek Polacek mpolacek at gcc dot gnu.org --- Taking. I think check_format_types needs a small tweak to look thru NOP_EXPRs.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Jakub Jelinek jakub at gcc dot gnu.org changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #3 from Jakub Jelinek jakub at gcc dot gnu.org --- Started with r209328.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Richard Biener rguenth at gcc dot gnu.org changed: What|Removed |Added Target Milestone|--- |5.0
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Marek Polacek mpolacek at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2015-02-12 CC||mpolacek at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Marek Polacek mpolacek at gcc dot gnu.org --- Confirmed.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Frank Ch. Eigler fche at redhat dot com changed: What|Removed |Added CC||fche at redhat dot com --- Comment #6 from Frank Ch. Eigler fche at redhat dot com --- Note that printf is a varargs function, and is defined to widen smaller-than-int parameters to at least int. unsigned short is subsumed in int.
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 --- Comment #7 from Marek Polacek mpolacek at gcc dot gnu.org --- Author: mpolacek Date: Fri Feb 13 07:56:14 2015 New Revision: 220677 URL: https://gcc.gnu.org/viewcvs?rev=220677root=gccview=rev Log: PR c/65040 * c-format.c (check_format_types): Don't warn about different signedness if the original value is in the range of WANTED_TYPE. * c-c++-common/pr65040.c: New test. Added: trunk/gcc/testsuite/c-c++-common/pr65040.c Modified: trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-format.c trunk/gcc/testsuite/ChangeLog
[Bug c/65040] [5 Regression] gcc-5 -Wformat broken
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65040 Marek Polacek mpolacek at gcc dot gnu.org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #8 from Marek Polacek mpolacek at gcc dot gnu.org --- Should be better now.
