Hi,

current definition of  macro __CONCAT() is limited, it does not allow to pass
__CONCAT()
as direct argument of __CONCAT(). The behaviour can be  shown by "gcc -E in.c" on

#define __CONCAT1(x,y)   x ## y
#define __CONCATN(x,y)   __CONCAT1(x,y)

__CONCAT1(First,__CONCAT1(Second,Third))
__CONCATN(First,__CONCATN(Second,Third))

Result of first test is First__CONCAT1(Second,Third), which is correct
behaviour of preprocessor , because "if an argument is stringified or
concatenated, the prescan does not occur".

But intuitively expected behaviour of __CONCAT()  would be same as result of
second test - FirstSecondThird.

Please, could you allow chaining of __CONCAT() via atached patch ?

Thanks

Petr