Re: Bug Report: \y, \B, \<, \> do not work with _

[Akim Demaille]

>>>>> "Paul" == Paul Eggert <address@hidden> writes:

Paul> Is your development version using the same dfa.[ch] and
Paul> regex.[ch] that the latest test GNU grep is using?

Akim> What's the difference between the two?

Paul> As it turns out, there was not much difference.

Paul> The problem is that glibc regex.c is incompatible with GNU grep
Paul> (and with BSD) because glibc rejects extended regular
Paul> expressions like '{'.

Huh?  I never realized this.  I don't get it: what does Emacs use
etc.?  Bah, don't bother, I'll check myself.

Paul> This incompatibility was introduced into glibc on 2000-01-18.  I
Paul> sent in a patch for this on 2000-03-03, but it got rejected on
Paul> the grounds that POSIX does not require support for those EREs.
Paul> This unnecessary incompatibility between glibc and BSD is a
Paul> problem, but I haven't had time to pursue the matter.

Then, what I don't understand why there are two files: dfa and re.
AFAICT they are really different, i.e., they require to be maintained
separately, so my question is more ``why do you maintain dfa _and_
regexp in grep and gawk, instead of just maintaining a fork from
glibc's regexp''.


Paul> So, as long as gawk does not sync to the latest glibc regex.c,
Paul> it should be OK here.

OK, I understand.  Thanks Paul!