Question

In xcode, while compiling apps with gcc, I want to throw compilation time errors if things like NSZombieEnabled is on for a distribution release, thus ensuring that compilation will fail and I won’t accidentally do something stupid.

I did some googling, but could not figure out how to cause the compiler to bail if a certain condition is met. Surely it must be easy, am I just not finding it?

Answer 1

Use the #error directive:

#if SHOULD_FAIL
#error "bad compiler!"
#endif

int main()
{
    return 0;
}

$ gcc a.c -DSHOULD_FAIL=0 # passes fine
$ gcc a.c -DSHOULD_FAIL=1
a.c:2:2: error: #error "bad compiler!"

Since NSZombieEnabled is an environment variable, you’ll need to do something clever in your build script to define your macro as zero or one.

Strictly speaking, the #error directive occurs in the C Preprocessor, not gcc. But that shouldn’t matter in the case you’ve described.