[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Bug#758911: libc6-dev: spurious sign-conversion warning for setrlimit, clang 3.5, _GNU_SOURCE

forwarded 758911 https://sourceware.org/bugzilla/show_bug.cgi?id=17307
affects 758911 +clang-3.5

On Sat, Aug 23, 2014 at 7:53 AM, Carlos O'Donell
<carlos@systemhalted.org> wrote:
> On Fri, Aug 22, 2014 at 3:23 PM, Zack Weinberg <zackw@panix.com> wrote:
>> I don't think it's reasonable for me to have to work around this in my code,
>> and indeed I don't see that there _is_ any workaround available to me in C.
>> (Maybe in C++ some template black magic to extract "the type of the first
>> argument to setrlimit"? Yech.)
> I agree.
> It isn't reasonable for users to have to work around this. Please file
> a bug with clang and ask them to come work with with upstream glibc to
> help provide better error checking and remove the spurious warning for
> this case.


clang bug: http://llvm.org/bugs/show_bug.cgi?id=20742
upstream libc bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17307

Both are annotated with the other.

> My opinion is that this is not a libc bug and I would suggest
> debian-glibc close this bug. You deviated from the standard the second
> you defined _GNU_SOURCE. If you want POSIX, but define _GNU_SOURCE,
> and then complain it's not *exactly* POSIX then I don't see what we
> did wrong.

When I define _GNU_SOURCE, I want POSIX conformance for everything
that POSIX specifies; I just *also* want some GNU extensions -- in the
case of the program that originally provoked this bug report,
`vasprintf`, `initgroups`, and `execvpe`.

Therefore, it is my considered opinion that defining _GNU_SOURCE
should not change the signature of any standard-specified function in
any way that is observable by correct code, even when arbitrarily
aggressive compiler warnings are activated.  "Correct" means "written
as if the functions had the signatures declared in the standard, and
provoking no undefined behavior."

(I'm willing to make an exception for when the standard itself has a
bug in it -- the obvious case that comes to mind is `struct timespec`,
whose `tv_nsec` field never should have been specified as bare `long`
in the first place.  But that sort of thing is going to wind up
affecting code that defines _POSIX_C_SOURCE or _XOPEN_SOURCE as well.)


Reply to: