Since you are already using cc extensions like ({ ... }), you may prefer
to use __COUNTER__ rather than __LINE__.
Consider preprocessor input like
#define X __LINE__
#define Y X,X,X,X
Y;
#undef X
#define X __COUNTER__
Y;
The first definition of X gives
4,4,4,4; // depending on the line that first Y; is on
and the second one gives
0,1,2,3;
This can be particularly important if mrs() is used multiple times in another
macro, since when the macro is expanded it is all expanded with the same
value for __LINE__.
Jeff
