You have to know that -Wextra exists, which I for one didn't until just now when...

seliopou · on May 26, 2010

-Wextra is total insanity. I just compiled some C code I've been working on with that flag, and got the following: "warning: signed and unsigned type in conditional expression." I was testing if a variable I declared as an integer was less than 0. To my knowledge, every number literal in C is assumed to be of a signed type unless followed by a 'u'. But now I know better. 0 is the exception.

swolchok · on May 26, 2010

Are you sure?

    $ echo 'int main(int argc, char **argv) { if (argc < 0) { return 1; } else {return 0;}}' > test.c
    $ gcc -v
    Using built-in specs.
    Target: x86_64-linux-gnu
    Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
    Thread model: posix
    gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) 
    $ gcc -Wall -Wextra test.c
    test.c: In function ‘main’:
    test.c:1: warning: unused parameter ‘argv’
    $

gcc-4.3.4 behaved the same way in my test.

humbledrone · on May 26, 2010

Yeah, that's why every programmer on the project has to be scrupulous about finding and correcting such errors. That's professionalism 101 -- if your team is not keeping the build warning free, things like this slip through.

tptacek · on May 26, 2010

Things like what, a blatantly obvious bug that would crash virtually every C program running on the system were it not for the fact that it was dead code?

This is practically a documentation bug.

[edit]

I kind of take it back, after mahmud's bzero() joke... out of oniguruma, Python, hexfiend, Apache, nginx, openssl, redis, regexkit, saxon, memcached, subversion, and valgrind, this hypothetical bug would have broken Python, redis, subversion, several apache modules, and memcached. The contents of my codebase/3p directory, FWIW.