Backslash newline at end of file warning

Question

With this code:

#include 


int main(int argc, char *argv[])
{

  return 0;
}


/** run2: A macro to call a function. */
#define run2( functi         


        

Answer 1

The following code generates the same warning under g++ 4.3.4 and g++ 4.5.1:

int main() {}
#define X \
Y

I must say I don't understand why. But you can get rid of the warning by adding an empty line at the end of the file.

Incidentally, this compiles without a warning, even without an empty last line:

int main() {}
#define X Y

So it looks like a pre-processor bug to me.

Edited to add: OK, not a bug as such. See my other answer for a more considered view.