[Patch, Fortran, OOP] PR 46313: OOP-ABI issue, ALLOCATE issue, CLASS renaming issue

[Tobias Schlüter]

On 2010-11-07 16:49, Janus Weil wrote:
> Btw, what is the reason for the macro adding *two* underscores in
> front, instead of just one?

I got curious and did some googling. Tthe C standard has this:
     7.1.3 Reserved identifiers

     Each header declares or defines all identifiers listed in its 
associated subclause, and optionally declares or defines identifiers 
listed in its associated future library directions subclause and 
identifiers which are always reserved either for any use or for use as 
file scope identifiers.

         * All identifiers that begin with an underscore and either an 
uppercase letter or another underscore are always reserved for any use.
...

So if the compiler can't use a character the user can't put into 
identifiers ('.' or '$'), it reverts to something that isn't allowed to 
put into identifiers: two underscores in the beginning.  I think the 
lesson for us is: '.' and '$' aren't portable.

Cheers,
- Tobi