On Fri, Aug 22, 2014 at 3:23 PM, Zack Weinberg <[email protected]> wrote: > glibc changes the signature of setrlimit() when _GNU_SOURCE is defined, "to > provide better error checking": > > extern int setrlimit (int, const struct rlimit *); // as specified by POSIX > extern int setrlimit (__rlimit_resource_t, const struct rlimit *); // > _GNU_SOURCE > > where __rlimit_resource_t is an enum with no negative values. This causes > some > compilers (e.g. clang-3.5) to give spurious warnings for programs that pass > non-constant values to setrlimit(), e.g. > > $ cat test.c > #define _GNU_SOURCE > #include <sys/resource.h> > int foo(int rsrc, struct rlimit *rl) > { > return setrlimit(rsrc, rl); > } > $ clang-3.5 -Wsign-conversion -c test.c > test.c:5:20: warning: implicit conversion changes signedness: 'int' to > '__rlimit_resource_t' (aka 'enum __rlimit_resource') > [-Wsign-conversion] > return setrlimit(rsrc, rl); > ~~~~~~~~~ ^~~~ > > 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. > I'm labeling this a libc bug rather than a clang bug because, if libc is going > to deviate from the standard "to provide better error checking", it needs to > ensure that standard-compliant code still works with no complaints, even at > quite aggressive warning levels. 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. At best this is an enhancement: "Be more POSIX-like if I define _GNU_SOURCE and happen to be using clang." Cheers, Carlos. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: https://lists.debian.org/CAE2sS1i=91o7k1rosvqvhchrtknkmrzbt5vt5+mpefb+yxo...@mail.gmail.com
