bug#24580: 25.2.50; query-replace history doesn't work

[Mark Oteiza <mvoteiza@udel.edu>]

On 02/10/16 at 10:02am, Eli Zaretskii wrote:
> > Date: Sun, 2 Oct 2016 00:17:15 -0400
> > From: Mark Oteiza <mvoteiza@udel.edu>
> > Cc: Marcin Borkowski <mbork@mbork.pl>, 24580@debbugs.gnu.org
> > 
> > > > - start emacs -Q
> > > > - press `a' `C-b', `M-%', `a', `RET', `b', `RET', `!'
> > > > - press `M-%', `M-p'
> > > > 
> > > > Emacs says "Beginning of history; no preceding item".
> > > 
> > > Mark, this regression was caused by the lexical-binding change in
> > > replace.el.  Could you please take a look?
> > 
> > The problem lies (at least) in query-replace-read-from, where
> > query-replace-from-to is let bound, and later read-from-minibuffer
> > refers to the symbol 'query-replace-from-to.  At first sight, it looks
> > like it could be fixed by putting some of the setup done by these
> > bindings into the minibuffer setup hook.
> 
> Isn't there a less intrusive change to fix this?  A significant change
> like the one you propose is more risky, but if there's no safer one, I
> guess we should take it.

Perhaps just adding a (defvar query-replace-from-to-history …) will be
sufficient.  That read-from-minibuffer and friends' HIST argument can
only be a symbol is a bit frustrating.

> > As for the other problem Marcin mentioned, that seems to be due to the
> > custom-reevaluate-setting call in the same function.
> 
> I'm not sure I understand: what's wrong with
> custom-reevaluate-setting in this case?

From -Q:

1. (setq-default query-replace-from-to-separator " => ")
2. Do an M-% (Like Marcin's in original recipe) once to get some default in the prompt
3. M-%

I would expect to see (default a => b) in the prompt, but
custom-reevaluate-setting apparently ignores settings done outside of
customize.  The first step instead needs to be

  (custom-set-variables '(query-replace-from-to-separator " => "))

or something with the default for query-replace-from-to-separator should
be changed.