Remove HISTSIZE env var altogether? (was: Re: [PATCH] Tweak the handling of $HISTSIZE edge cases [PR gdb/16999])

[Pedro Alves <palves@redhat.com>]

Changing title to call for attention.  Maybe we should ask
on gdb@.  Background here:

 https://sourceware.org/ml/gdb-patches/2015-05/msg00349.html
 https://sourceware.org/ml/gdb-patches/2015-05/msg00563.html

> What do you think about removing HISTSIZE/GDBHISTSIZE support
> altogether?  It is awfully redundant (we can already automatically set
> the history size via .gdbinit or via -ex "set history size foo") and
> thus not really useful.  Even if we go along with replacing HISTSIZE
> with GDBHISTSIZE I just can't see much use for it.

What about GDBHISTFILE?  I think that the rationale for the existence
of one should apply to both.  (with the HISTSIZE vs GDBHISTSIZE distinction
being a separate matter.)

I'm really not sure.  Trying to play devil's advocate:

#1 - An env var can be set once, for all users.  But that can be
   done with --with-system-gdbinit=FILE as well.

#2 - Along with GDBHISTFILE, it survives -nx.  Does it really matter?
   I don't know.

#3 - Seems friendly to allow at least GDBHISTFILE be an env var so it
   can easily be toggled per host.  Though that can be done through
   Python inside .gdbinit nowadays.  Though^2, Python isn't always
   available.

OTOH, I'm getting more convinced that we should at least
rename HISTSIZE -> GDBHISTSIZE.  The cost of keeping that
doesn't seem to be much.

Thanks,
Pedro Alves