bug#40731: [PATCH] Make emacsclient fail if --eval is used and no Emacs server connection established

bug#40731: [PATCH] Make emacsclient fail if --eval is used and no Emacs server connection established

[Ilya Ostapyshyn]

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Hello,

This patch makes emacsclient quit with an error message if both --eval
and --alternate-editor were specified.

According to the current implementation, the emacsclient runs
alternate-editor, treating the eval expression as the filename, which
is IMO not very intuitive.

Kind regards,
Illia.


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From dcc18914c7109c06d570790d24b44f99ceb2a5d7 Mon Sep 17 00:00:00 2001
From: Ilya Ostapyshyn <ilya.ostapyshyn@gmail.com>
Date: Mon, 20 Apr 2020 15:06:07 +0300
Subject: [PATCH] exit if no connection and --eval used

---
 lib-src/emacsclient.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib-src/emacsclient.c b/lib-src/emacsclient.c
index 380be95222..d74750ea5d 100644
--- a/lib-src/emacsclient.c
+++ b/lib-src/emacsclient.c
@@ -691,14 +691,21 @@ print_help_and_exit (void)
   exit (EXIT_SUCCESS);
 }
 
-/* Try to run a different command, or --if no alternate editor is
+/* If args were to be evaluated exit immediately with an error code.
+   Try to run a different command, or --if no alternate editor is
    defined-- exit with an error code.
    Uses argv, but gets it from the global variable main_argv.  */
 
 static _Noreturn void
 fail (void)
 {
-  if (alternate_editor)
+  if (eval)
+    {
+      /* No way to evaluate Lisp expressions if there is
+         no connection to an Emacs server.  */
+      message (true, "%s: unable evaluate ELisp expressions.\n", progname);
+    }
+  else if (alternate_editor)
     {
       size_t extra_args_size = (main_argc - optind + 1) * sizeof (char *);
       size_t new_argv_size = extra_args_size;
-- 
2.26.1

bug#40731: Followup

[Ilya Ostapyshyn]

I have found a commit ~6fe661342a24edcaea255c3ba9a37613031554da~ which
addressed the same issue but in a different way.

However, the commit was reverted
(hash ~f198a5c5144fdded1400df6e8454e4b1b912c7de~) with the following message:

> The alternate editor may be Emacs, which is useful when you want to
> eval something in an existing Emacs (if it exists), or in a new Emacs
> if there's no server running.

I beg to differ. In fact, the --eval is not an optarg parameter, instead
it tells emacsclient to treat the whole FILE argument as lisp
expressions for evaluation.

Therefore, invoking
  emacsclient -a emacs -e '(emacs-version)'
just opens a file named "(emacs-version)" in a new instance of Emacs if
server is not running.

bug#40731: Followup

[Lars Ingebrigtsen]

Ilya Ostapyshyn <ilya.ostapyshyn@gmail.com> writes:

> I have found a commit ~6fe661342a24edcaea255c3ba9a37613031554da~ which
> addressed the same issue but in a different way.
>
> However, the commit was reverted
> (hash ~f198a5c5144fdded1400df6e8454e4b1b912c7de~) with the following message:
>
>> The alternate editor may be Emacs, which is useful when you want to
>> eval something in an existing Emacs (if it exists), or in a new Emacs
>> if there's no server running.
>
> I beg to differ. In fact, the --eval is not an optarg parameter, instead
> it tells emacsclient to treat the whole FILE argument as lisp
> expressions for evaluation.
>
> Therefore, invoking
>   emacsclient -a emacs -e '(emacs-version)'
> just opens a file named "(emacs-version)" in a new instance of Emacs if
> server is not running.

Hm.  Unfortunately the reverting commit doesn't refer to the test case
that somebody had for this, but there was a complaint after the change
that the change ruined their work flow.

There was a test case for this, but it wasn't included in the reversion
commit, and I don't recall what it was now...

emacsclient -a "emacs -e" -e '(emacs-version)'

or something?

In any case, we can't regress this work flow, so we can't fix this
somewhat illogical way emacsclient works, so I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no