bug#32502: 27.0.50; Tramp; C-g during asynchronous remote find-file kills Emacs

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: gazally@runbox.com,  32502@debbugs.gnu.org
> Date: Thu, 30 Aug 2018 09:09:42 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> So it looks like you are right: we cannot send signals to the main
> >> thread. Is this acceptable?
> >
> > Yes, I think so, but let's document that.
> 
> Sounds to me like a serious restriction. When something happens in a
> thread, I want to know it. There isn't even a message about the error.

If we want to announce the errors to the main thread, we can use
methods other than signaling an error.  For example, we could inject
a special event into the input queue, similarly to how we produce
help-echo and other special events.

Fsignal is a very blunt weapon, its main effect is to throw to top
level.  Why would we want to do that _in_the_main_thread_ when the
problem happened in another thread?  That's disruptive, and could even
mean that the user will lose their edits.  Not nice, IMO.