bug#53758: 28.0.91; Recursive edit during dired-do-find-regexp-and-replace breaks isearch

[Dmitry Gutov]

Hi Juri,

On 06.02.2022 19:44, Juri Linkov wrote:
> > isearch-forward (C-s) while in a recursive edit (C-r) triggered from
> > dired-do-find-regexp-and-replace (Q in a dired buffer) always fails to
> > find any matches for any string, even if there are matches in the
> > buffer.
> >
> > Steps to reproduce:
> > 1. Open a dired buffer in a directory containing at least one file which
> > contains some text (e.g. "Hello world")
> > 2. Run dired-do-find-regexp-and-replace to replace "Hello" with
> > "Goodbye" ("Q Hello RET Goodbye RET"); this will switch buffers
> > to the first matching file.
> > 3. Type C-r to enter a recursive edit (I'm guessing this runs
> > (recursive-edit)?)
> > 4. At the start of the buffer, run isearch-forward searching for "world"
> > ("C-s world RET")
> > 5. Note that the isearch fails despite "world" being in the buffer.
> >
> > For what it's worth, this interestingly doesn't happen with
> > project-query-regexp-replace (which also does multi-file query-replace).
> This is because of these lines in xref--query-replace-1:
>
>           ;; Counteract the "do the next match now" hack in
>           ;; `perform-replace'.  And still, it'll report that those
>           ;; matches were "filtered out" at the end.
>           (isearch-filter-predicate
>            (lambda (beg end)
>              (and current-beg
>                   (>= beg current-beg)
>                   (<= end current-end))))
>
> Dmitry, could you please explain the comment above.
> What I don't understand is where this
> "the next match now" hack is in `perform-replace'?

It's referring to the comment on lines starting with 2938 and the 
subsequent code which uses 'looking-at' instead of 
replace-re-search-function.

Here's that comment in full:

          ;; Otherwise, if matching a regular expression, do the next
          ;; match now, since the replacement for this match may
          ;; affect whether the next match is adjacent to this one.
          ;; If that match is empty, don't use it.

I'm not sure why the result would be different between 
dired-do-find-regexp-and-replace and project-query-regexp-replace, though.