#define IF(cond,block) if ((cond)) block

int main() {
  IF(1,{ int a, b; })
  return 0;
}

Line 20: error: macro "IF" passed 3 arguments, but takes just 2
In function 'main':
Line 6: error: 'IF' undeclared (first use in this function)
Line 6: error: (Each undeclared identifier is reported only once
Line 6: error: for each function it appears in.)
Line 7: error: expected ';' before 'return'