Re: regex.c simplification

[Paul Eggert]

On 07/19/2018 11:59 PM, Eli Zaretskii wrote:
> > I was thinking of just always using the libc regexp code (whether it's
> > GNU libc or something else).
> Yes, that'd be a possibility.  Do we have any supported platform that
> does NOT have its own regexp code, whether in libc or as a separate
> library?
Every POSIX-conforming platform has regexp code somewhere, using the 
POSIX API. However, I can see some trouble using that code:

* Some of libc regex implementations have been reasonably buggy. Most 
GNU apps don't use these implementations any more so I'm not sure what 
their status is.

* We may need to use an option like -lregex to get the system library 
implementation, and that would have to be configured.

* Perhaps 'etags' users are using GNU extensions in their regular 
expressions, and if we switch to the libc API their usage will break.

* You're the expert, but as far as I know MS-Windows does not support 
the POSIX API so presumably we'd have to provide a substitute anyway, 
for MS-Windows.

* etags uses the GNU API so it would have to be changed to use the POSIX 
API.