On Fri, Dec 16, 2016 at 07:00:06PM +0000, Joseph Myers wrote:
> On Fri, 16 Dec 2016, Martin Sebor wrote:
>
> > I don't claim it can't be improved but it seems pretty good as
> > it is already. Among the 6 instances it's found in GCC three
> > look like real bugs.
>
> FWIW it's found at least one real bug in glibc
> <https://sourceware.org/bugzilla/show_bug.cgi?id=20978> - that's a case
> where strlen is called on a pointer that can never be non-null if the
> strlen call is reached. (I don't know if there are other cases in glibc,
> whether genuine bugs or false positives, that would appear later in the
> build once that bug is fixed.)
Thanks. Reduced to something like:
int
foo (const char *name)
{
if (name)
return 6;
return __builtin_strlen (name);
}
This is warned about both with Martin's late warning and my after ccp2
warning version. We should include it in gcc testsuite.
Jakub
