gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
Compiling libguestfs using gcc-4.6.0-0.11.fc15.x86_64 gives lots of:
error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to
X cmp C1 +- C2 [-Werror=strict-overflow]
These seem to be associated with code that does 'if (strcmp (s1, s2) == 0)'
For example:
dir.c: In function ‘do_rm_rf’:
dir.c:59:7: error: assuming signed overflow does not occur when changing X +-
C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
--
int
do_rm_rf (const char *path)
{
int r;
char *buf, *err;
if (STREQ (path, /)) { -- here
reply_with_error (cannot remove root directory);
return -1;
}
--
where STREQ is a simple macro:
#define STREQ(a,b) (strcmp((a),(b)) == 0)
AFAIK this code should be correct? I can't find anything at all about
this specific error from Google.
Rich.
--
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Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
On 3/7/11 9:49 AM, Richard W.M. Jones wrote: Compiling libguestfs using gcc-4.6.0-0.11.fc15.x86_64 gives lots of: error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow] These seem to be associated with code that does 'if (strcmp (s1, s2) == 0)' For example: dir.c: In function ‘do_rm_rf’: dir.c:59:7: error: assuming signed overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow] I'm not able to repro this with -0.12.fc15. If I had to guess, you've got a macro for strcmp somewhere that's making type assumptions. What does the .i file look like if you compile with -save-temps ? - ajax -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
gcc-4.6.0-0.12.fc15.x86_64 breaks strcmp? (was: Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?)
On Mon, Mar 07, 2011 at 10:14:57AM -0500, Adam Jackson wrote:
On 3/7/11 9:49 AM, Richard W.M. Jones wrote:
Compiling libguestfs using gcc-4.6.0-0.11.fc15.x86_64 gives lots of:
error: assuming signed overflow does not occur when changing X +- C1
cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
These seem to be associated with code that does 'if (strcmp (s1, s2)
== 0)'
For example:
dir.c: In function ‘do_rm_rf’: dir.c:59:7: error: assuming signed
overflow does not occur when changing X +- C1 cmp C2 to X cmp C1 +-
C2 [-Werror=strict-overflow]
I'm not able to repro this with -0.12.fc15.
Firstly, I have just installed -0.12 and I can reproduce it.
If I had to guess,
you've got a macro for strcmp somewhere that's making type
assumptions. What does the .i file look like if you compile with
-save-temps ?
OK ... When you said that, I initially suspected gnulib (which I am
using in this code), but I cannot see gnulib doing any macros or
replacement of strcmp.
Below is how the failure line expands(!)
--
if ((__extension__ ({ size_t __s1_len, __s2_len; (__builtin_constant_p
((path)) __builtin_constant_p ((/)) (__s1_len = strlen ((path)),
__s2_len = strlen ((/)), (!((size_t)(const void *)(((path)) + 1) -
(size_t)(const void *)((path)) == 1) || __s1_len = 4) (!((size_t)(const
void *)(((/)) + 1) - (size_t)(const void *)((/)) == 1) || __s2_len = 4)) ?
__builtin_strcmp ((path), (/)) : (__builtin_constant_p ((path))
((size_t)(const void *)(((path)) + 1) - (size_t)(const void *)((path)) == 1)
(__s1_len = strlen ((path)), __s1_len 4) ? (__builtin_constant_p ((/))
((size_t)(const void *)(((/)) + 1) - (size_t)(const void *)((/)) == 1) ?
__builtin_strcmp ((path), (/)) : (__extension__ ({ __const unsigned char
*__s2 = (__const unsigned char *) (__const char *) ((/)); register int
__result = (((__const unsigned char *) (__const char *) ((path)))[0] -
__s2[0]); if (__s1_len 0 __result == 0) { __result = (((__const unsigned
char *) (__const char *) ((path)))[1] - __s2[1]); if (__s1_len 1 __result
== 0) { __result = (((__const unsigned char *) (__const char *) ((path)))[2] -
__s2[2]); if (__s1_len 2 __result == 0) __result = (((__const unsigned
char *) (__const char *) ((path)))[3] - __s2[3]); } } __result; }))) :
(__builtin_constant_p ((/)) ((size_t)(const void *)(((/)) + 1) -
(size_t)(const void *)((/)) == 1) (__s2_len = strlen ((/)), __s2_len
4) ? (__builtin_constant_p ((path)) ((size_t)(const void *)(((path)) + 1) -
(size_t)(const void *)((path)) == 1) ? __builtin_strcmp ((path), (/)) :
(__extension__ ({ __const unsigned char *__s1 = (__const unsigned char *)
(__const char *) ((path)); register int __result = __s1[0] - ((__const unsigned
char *) (__const char *) ((/)))[0]; if (__s2_len 0 __result == 0) {
__result = (__s1[1] - ((__const unsigned char *) (__const char *) ((/)))[1]);
if (__s2_len 1 __result == 0) { __result = (__s1[2] - ((__const unsigned
char *) (__const char *) ((/)))[2]); if (__s2_len 2 __result == 0)
__result = (__s1[3] - ((__const unsigned char *) (__const char *) ((/)))[3]);
} } __result; }))) : __builtin_strcmp ((path), (/); }) == 0)) {
--
Rich.
--
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virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
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Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
On Mon, Mar 7, 2011 at 3:49 PM, Richard W.M. Jones rjo...@redhat.com wrote:
Compiling libguestfs using gcc-4.6.0-0.11.fc15.x86_64 gives lots of:
error: assuming signed overflow does not occur when changing X +- C1 cmp C2
to X cmp C1 +- C2 [-Werror=strict-overflow]
These seem to be associated with code that does 'if (strcmp (s1, s2) == 0)'
For example:
dir.c: In function ‘do_rm_rf’:
dir.c:59:7: error: assuming signed overflow does not occur when changing X +-
C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
--
int
do_rm_rf (const char *path)
{
int r;
char *buf, *err;
if (STREQ (path, /)) { -- here
reply_with_error (cannot remove root directory);
return -1;
}
--
where STREQ is a simple macro:
#define STREQ(a,b) (strcmp((a),(b)) == 0)
I remeber that gnu lib have a similar macro, and last year there was a
fix
http://old.nabble.com/-PATCH--define-STREQ%28a,-b%29-consistently,-removing-useless-parentheses-td27293621.html
But also in libvirt apparently
http://www.redhat.com/archives/libvir-list/2010-February/msg00010.html
Dunno if this if OT or no
Regards
Regards
Regards
AFAIK this code should be correct? I can't find anything at all about
this specific error from Google.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
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Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
On Mon, Mar 07, 2011 at 04:37:20PM +0100, yersinia wrote: I remeber that gnu lib have a similar macro, and last year there was a fix http://old.nabble.com/-PATCH--define-STREQ%28a,-b%29-consistently,-removing-useless-parentheses-td27293621.html I understand Jim's argument, although I think I'd rather leave those parentheses in for safety. In any case, I tried it without them and as expected it didn't make any difference to this problem. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
Richard W.M. Jones wrote:
Compiling libguestfs using gcc-4.6.0-0.11.fc15.x86_64 gives lots of:
error: assuming signed overflow does not occur when changing X +- C1 cmp C2
to X cmp C1 +- C2 [-Werror=strict-overflow]
These seem to be associated with code that does 'if (strcmp (s1, s2) == 0)'
For example:
dir.c: In function ‘do_rm_rf’:
dir.c:59:7: error: assuming signed overflow does not occur when changing X +-
C1 cmp C2 to X cmp C1 +- C2 [-Werror=strict-overflow]
--
int
do_rm_rf (const char *path)
{
int r;
char *buf, *err;
if (STREQ (path, /)) { -- here
reply_with_error (cannot remove root directory);
return -1;
}
--
where STREQ is a simple macro:
#define STREQ(a,b) (strcmp((a),(b)) == 0)
AFAIK this code should be correct? I can't find anything at all about
this specific error from Google.
Hi Rich,
I suspect that there was a problem with .11, perhaps one of these:
* Fri Mar 04 2011 Jakub Jelinek ja...@redhat.com 4.6.0-0.12
- update from trunk
- PRs c++/46159, c++/46282, c++/47200, c++/47774, c++/47851, c++/47950,
c++/47974, c/47963, libstdc++/47913, middle-end/47283,
rtl-optimization/47925, target/47935, tree-optimization/47890
- rebuilt against ppl 0.11.2, reenable cloog-ppl Requires
because I can't reproduce that with the latest in rawhide,
gcc-4.6.0-0.12.fc15.x86_64:
$ cat k.c :
#define STREQ(a,b) (strcmp((a),(b)) == 0)
int
do_rm_rf (const char *path)
{
int r;
char *buf, *err;
if (STREQ (path, /))
{
reply_with_error (cannot remove root directory);
return -1;
}
}
$ gcc -O3 -c k.c -Werror=strict-overflow :
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Re: gcc-4.6.0-0.11.fc15.x86_64 breaks strcmp?
On Mon, Mar 07, 2011 at 05:09:17PM +0100, Jim Meyering wrote:
I suspect that there was a problem with .11, perhaps one of these:
* Fri Mar 04 2011 Jakub Jelinek ja...@redhat.com 4.6.0-0.12
- update from trunk
- PRs c++/46159, c++/46282, c++/47200, c++/47774, c++/47851, c++/47950,
c++/47974, c/47963, libstdc++/47913, middle-end/47283,
rtl-optimization/47925, target/47935, tree-optimization/47890
- rebuilt against ppl 0.11.2, reenable cloog-ppl Requires
because I can't reproduce that with the latest in rawhide,
gcc-4.6.0-0.12.fc15.x86_64:
You forgot to #include string.h
$ cat k.c
:
#define STREQ(a,b) (strcmp((a),(b)) == 0)
int
do_rm_rf (const char *path)
{
int r;
char *buf, *err;
if (STREQ (path, /))
{
reply_with_error (cannot remove root directory);
return -1;
}
}
$ gcc -O3 -c k.c -Werror=strict-overflow
:
I can reproduce it and have filed http://gcc.gnu.org/PR48022 for it.
Jakub
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