bug#32169: 27.0.50; Wishlist: cleanup of thread-last-error

[Michael Albinus <michael.albinus@gmx.de>]

Eli Zaretskii <eliz@gnu.org> writes:

Hi Eli,

>> When a thread has died, `thread-last-error' reports the reason. But
>> there is no possibility to cleanup this last error, which makes it
>> inconvenient to check for errors in further threads. A function
>> `cleanup-thread-last-error' or alike would be helpful.
>
> How about having thread-last-error clear the error as a side effect,
> perhaps when called with an optional argument?

I'd be happy with either variant.

> (Btw, I'd rather we made error reporting in non-main threads much more
> solid than what we have now.)

While working on making Tramp threadsafe, I use the following instead of
`signal':

(defsubst tramp-compat-signal (error-symbol data)
  "Signal an error to the main thread."
  (when tramp-compat-main-thread
    (tramp-compat-funcall
     'thread-signal tramp-compat-main-thread error-symbol data))
  (signal error-symbol data))

Works sufficient so far. `tramp-compat-main-thread' is a defconst, which
has as value (car (all-threads)). And `tramp-compat-funcall' is a Tramp
internal macro, good for backward compatibility with Emacs 24 and 25.

Best regards, Michael.

PS: Maybe I shall push this to a git branch, giving people a chance for
early tests. `find-file-noselect' survives already in simple cases, w/o
an Emacs crash.