How can I print the result of sizeof() at compile time in C?

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I was mucking around looking for similar functionality when I stumbled on this:

Is it possible to print out the size of a C++ class at compile-time?

Which gave me the idea for this:

char (*__kaboom)[sizeof( YourTypeHere )] = 1;

Which results in the following warning in VS2015:

warning C4047: 'initializing': 'DWORD (*)[88]' differs in levels of indirection from 'int'

where 88 in this case would be the size you’re looking for.

Super hacky, but it does the trick. Probably a couple years too late, but hopefully this will be useful to someone.

I haven’t had a chance to try with gcc or clang yet, but I’ll try to confirm whether or not it works if someone doesn’t get to it before me.

Edit: Works out of the box for clang 3.6

The only trick I could get to work for GCC was abusing -Wformat and having the macro define a function like the following:

void kaboom_print( void )
{
    printf( "%d", __kaboom );
}

Which will give you a warning like:

...blah blah blah... argument 2 has type 'char (*)[88]'

Slightly more gross than the original suggestion, but maybe someone who knows gcc a bit better can think of a better warning to abuse.

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