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

[Basil Contovounesios via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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

  Debugger entered--Lisp error: (wrong-type-argument stringp nil)
    string-match("\0" nil 0)
    split-string(nil "\0" t)
    project--vc-list-files("/tmp/my-VHbIUg/" Git nil)
    #f(compiled-function (dir) #<bytecode 0x12e526b1f733674a>)("/tmp/my-VHbIUg/")
    mapcan(#f(compiled-function (dir) #<bytecode 0x12e526b1f733674a>) ("/tmp/my-VHbIUg/"))
    #f(compiled-function (project &optional dirs) #<bytecode 0xea2b226a1860ab9>)((vc Git "/tmp/my-VHbIUg/"))
    apply(#f(compiled-function (project &optional dirs) #<bytecode 0xea2b226a1860ab9>)
          (vc Git "/tmp/my-VHbIUg/") nil)
    project-files((vc Git "/tmp/my-VHbIUg/"))

> I'll leave it up to you, Basil, to decide whether to close or leave this
> bug open.

Closing, since the difference between master and emacs-29 materialised
in the context of Eglot.

If Dmitry thinks project-files is doing something unexpected, we can
open a new ticket if necessary.

Thanks,

-- 
Basil