bug#24616: 26.0.50; No backtrace when emacsclient --eval fails

[npostavs]

Eli Zaretskii <eliz@gnu.org> writes:
>> >> Just a note: you can get a backtrace by setting debug-on-signal
>> >> instead of debug-on-error.
>> >
>> > Really?
>> >
>> > $ emacsclient --eval '(progn (defun f () (error "foo")) (setq 
>> > debug-on-signal t debug-on-error t) (f))'
>> > *ERROR*: foo
>> >
>> > Am I missing something obvious?
>> 
>> The backtrace shows up in Emacs, where the server is running.
>
> How about adding this to debugging.texi?

Something like this?

diff --git i/doc/lispref/debugging.texi w/doc/lispref/debugging.texi
index c88a2fa..bb3ced4 100644
--- i/doc/lispref/debugging.texi
+++ w/doc/lispref/debugging.texi
@@ -152,6 +152,11 @@ Error Debugging
 must still fulfill the criteria specified by @code{debug-on-error} and
 @code{debug-ignored-errors}.)
 
+For example, setting this variable is useful to get a backtrace from
+code evaluated by emacsclient.  If elisp code evaluated by emacsclient
+signals an error while this variable is non-@code{nil}, the backtrace
+will popup in the running Emacs.
+
 @strong{Warning:} Setting this variable to non-@code{nil} may have
 annoying effects.  Various parts of Emacs catch errors in the normal
 course of affairs, and you may not even realize that errors happen