Re: [Bug-gnulib] Re: include-once-only macros

[Paul Eggert]

Simon Josefsson <address@hidden> writes:

> Paul Eggert <address@hidden> writes:
>> C99 reserves all identifiers that begin with an underscore and either
>> an uppercase letter or another underscore, for any use.  (Some other
>> identifiers are also reserved, in some contexts.)
>
> And POSIX doesn't further refine this?

Yes: it reserves even more identifiers, and it specifies the meaning
of some identifiers in space reserved by the C standard.  For example,
it specifes several identifiers that begin with _POSIX_, including
feature-test macros like _POSIX_C_SOURCE that the user is allowed to
define.  The _[A-Z]* identifiers that POSIX doesn't specify are still
reserved.