bug#73880: Master: emacs-lisp-mode: Tab completion for a function position fails in a `let' form.

[Dmitry Gutov <dmitry@gutov.dev>]

On 27/10/2024 01:09, Alan Mackenzie wrote:
>> BTW, I had to move the corresponding piece of code to a separate
>> function to debug it. Too bad edebug doesn't know how to jump into the
>> 'guard' clauses.
> I found the bug in pcase.el causing this.  The edebug spec element
> &interpose, which is used in pcase-PAT absolutely requires that the
> function it uses (in this case pcase--edebug-match-pat-args) must call
> PF.  (See edebug.el around L1810.)
> 
> What PF (internal function in edebug) does is join up edebug specs with
> what follows.
> 
> pcase--edebug-match-pat-args fails to do this for most cases it deals
> with, including guard.  As a result, there is no edebug instrumentation
> generated for the argument of guard.
> 
> I'm going to raise a bug report for this (answering my question in my
> last post).  In the meantime, here is a rough first draught of a fix.
> With it, I can debug the guard clauses in elisp-completion-at-point,
> though I seem to be triggering other problems (I get a message about a
> `_' argument being used after all).

Nice! It works, thank you.