Re: regex.c: emacs & glibc (and xemacs, and grep and ...)

[Richard Stallman]

    Emacs comes with it's own version of regex.c, even though most UNIX
    systems have a regex implementation.  IIUC, this is for portability.

Also because we had to have one for GNU.

    Suppose glibc's regex and Emacs' regex are unified - will Emacs still
    build it's own regex version even on gnu systems (linux, hurd)?

Yes, because it has special conditionalized features specifically for
Emacs which were not compiled in when using it for Glibc.
Unless we were to provide interfaces for those things in Glibc,
the system-supplied regex will never be usable.

    Finally, GNU CLISP (http://clisp.cons.org) comes with a GNU regex.c of
    1994(!) - which version should we upgrade to?  Emacs?  GLIBC? GNU grep?

I wish I knew.  The versions diverged due to inattention,
and recently a completely new regex was put into Glibc.
I am told it has major problems.  Supposing they are fixed,
you will probably want to use that one in CLISP.