bug#62741: 30.0.50; Eglot jdtls project test: pass on emacs-29, fail on master

[João Távora]

On Mon, Apr 10, 2023 at 10:11 AM Basil Contovounesios <contovob@tcd.ie> wrote:
>
> close 62741 30.1
> severity 62741 minor
> quit
>
> João Távora [2023-04-10 09:17 +0100] wrote:
>
> > Pasting the backtrace here for Dmitry to have a look.
> >
> > Test eglot-test-eclipse-connect backtrace:
> >   string-match("\0" nil 0)
> >   split-string(nil "\0" t)
> >   project--vc-list-files("/tmp/eglot--fixturernYTOR/project/" Git nil)
> >   #f(compiled-function (dir) #<bytecode 
> > -0xa5be45661654310>)("/tmp/eglot--fixturernYTOR/project/")
> >   mapcan(#f(compiled-function (dir) #<bytecode -0xa5be45661654310>) 
> > ("/tmp/eglot--fixturernYTOR/project/"))
> >   #f(compiled-function (project &optional dirs) #<bytecode 
> > 0x114f4cd06dfc2088>)((vc Git "/tmp/eglot--fixturernYTOR/project/"))
> >   apply(#f(compiled-function (project &optional dirs) #<bytecode 
> > 0x114f4cd06dfc2088>) (vc Git "/tmp/eglot--fixturernYTOR/project/") nil)
> >   project-files((vc Git "/tmp/eglot--fixturernYTOR/project/"))
> >
> > It would seem that the problem here is there are no files versioned yet,
> > so this expression in project--vc-list-files
> >
> >    (apply #'vc-git--run-command-string nil "ls-files" args)
> >
> > Returns nil.
> >
> > But I cannot reproduce this locally.
>
> It's easy to reproduce the backtrace without Eglot, and it happens both
> on master and emacs-29.  From emacs -Q:
>
>   (let ((dir (make-nearby-temp-file "my-" t)))
>     (unwind-protect
>         (let ((default-directory (file-name-as-directory dir)))
>           (make-directory ".git")
>           (make-empty-file "file") ; Optional.
>           (require 'project)
>           (project-files (project-current)))
>       (delete-directory dir t)))
>
>   C-x C-e

This indeed breaks, but it doesn't break if you replace the
'make-directory' with '(shell-command "git init")'.

And yet, when you tried that in Eglot's CI, it seem it _did_
break with the same error.  So I don't know what's going on.

João