bug#25561: 25.1; "Making isearch-search-fun-function local to *Minibuf-1* while let-bound!" warning with Evil

[Vasilij Schneidermann <v.schneidermann@gmail.com>]

Bumping this thread to CC Stefan Monnier as well.

On 01/29/17 at 02:39am, Juri Linkov wrote:
> > Hello,
> >
> > a user of the Evil package reported [1] that using a search command
> > results in a "Making isearch-search-fun-function local to *Minibuf-1*
> > while let-bound!" warning.  This appears to be an interaction between
> > isearch and Evil, more specifically, Evil let-binds
> > `isearch-search-fun-function' to something of its own, invokes isearch
> > and something in isearch ends up running
> > `minibuffer-history-isearch-setup' which `make-local-variable' to have
> > `isearch-search-fun-function' have a separate value, resulting in the
> > aforementioned warning.
> >
> > What's the recommended way to avoid or silence it?  Stefan suggested
> > elsewhere [2] that this might indicate a bug, hence why I'm bringing
> > this up here.
> >
> > [1]: https://github.com/emacs-evil/evil/issues/748
> > [2]: https://lists.gnu.org/archive/html/emacs-devel/2010-06/msg00903.html
> 
> Thanks for the report.  I'm not familiar with the Evil package,
> so please correct me if I make wrong guesses about it.  I suppose
> that the basic mode of operation of the Evil package is not buffer-local.
> In this case I believe (make-local-variable 'isearch-search-fun-function)
> is the wrong fix because it will make this variable have this value
> in every random buffer where the user happens to invoke the search command.
> 
> OTOH, if evil-mode is the global mode then it makes sense to change the
> global value of isearch-search-fun-function (and perhaps keeping its
> old value).  If you need to keep standard search commands working,
> then you could create a new internal defvar e.g. evil-search-is-active,
> set it temporarily in evil-search commands, and check it in your new
> implementation of the search function in isearch-search-fun-function.
> If evil-search-is-active is nil, then call the old default value
> isearch-search-fun-default.
> 
> I can't guarantee this solution to work, it's just an idea for you
> to consider.