[cfe-dev] sizeof(sizeof(...))

[Mike Stump]

On Dec 14, 2007, at 12:30 PM, Ted Kremenek wrote:
> Does anyone have any insights on the semantics of expressions of the  
> form sizeof(sizeof(...))?

As you suspected the argument isn't evaluated because the type of the  
argument isn't a variable length array.  Put on your recursion hat and  
just think about the first bit of the operand....

sizeof (...)  has type size_t.

size_t isn't a VLA.

no need to consider anything instead of the (...).


For fun, try the follow on the old gray matter:

struct { char o[n][m]; } foo(int n, int m) { }

int main() {
   return sizeof(foo(3,4));
}

:-)