On Fri, 15 Jan 2010 21:57:32 +0200, Dirk-Jan C. Binnema <djcb.bulk@gmail.com> wrote:
>     Olly> Underscore prefixed identifiers are reserved by ISO C at file-scope;
>     Olly> using them yourself is undefined behaviour...
> 
> Ah, thanks for reminding, I thought it was __ and _C (capital), but you are
> right:
> 
> ,---- (7.1.3 Reserved identifiers)
> |  All identifiers that begin with an underscore and either an uppercase letter
> |  or another underscore are always reserved for any use.
> | 
> | — All identifiers that begin with an underscore are always reserved for use as
> | identifiers with file scope in both the ordinary and tag name spaces.
> `----

But please don't be too strict about this.

Please feel very free to use any identifier with a _notmuch prefix.

And really, feel free to use just about any underscore-prefixed
identifier that you want that doesn't clash with anything on your
system.

Then if we do identify an actual clash somewhere then we can fix it.

I think it was stupid of Posix to steal _ and a reserved prefix, and I
really don't have a problem ignoring that. This is like I described in a
recent mail---trying to prevent all portability problems just isn't
worth the effort. It's much easier to fix problems that actually occur
in practice.

-Carl