07:49 <Shinmera> Doing something like (let ((string (make-string 1000))) (map-into string (lambda () (code-char (random #xFFFF)))))

07:49 <Shinmera> will very often result in an error

07:49 <Shinmera> Invalid protocol message: Error during string-to-utf8: Unable to encode character 28320 as :UTF-8.

07:50 <Shinmera> This is very annoying if the string occurs in a backtrace, as SLDB fails to launch at all

08:11 <luis> Shinmera: that is actually a valid character isn't it? Did you make up that number?

08:11 <Shinmera> I pasted the error.

08:12 <Shinmera> You can try the snippet yourself, it'll very likely produce a similar error with different code points.

08:13 <Shinmera> But yeah, all #xFFFF code-points are valid unicode.

08:14 <Shinmera> I stumbled on this because I'm implementing unicode algorithms and want to test my stuff against random garbage attacks. Debugging that without SLDB is... troublesome.

08:19 <luis> My memory is fuzzy but there are some non-characters but it's probably only CCL that's pedant about it.

08:21 <Shinmera> Hmm, ok, let me double-check then

08:22 <luis> (I ran into that when implementing UTF-8B support for Babel)

08:23 <Shinmera> Looks like D800 to DFFF are considered invalid code points indeed

08:23 <luis> But 28320 is not one of those is it?

08:24 <luis> (I'm on my phone. :-/)

08:24 <Shinmera> That's 6EA0

08:24 <Shinmera> Another one is 9FB0

08:27 <luis> Can you come up with a direct string-to-utf8 call that fails? Perhaps outside SLIME.

08:29 <Shinmera> Yeah, I'll try

08:30 <Shinmera> Hmm. I think the error message is misleading and points to a character close to an invalid one.

08:30 <Shinmera> Because if I explicitly ignore the D800-DFFF range in my random generator there's no more faults

08:32 <luis> That's... Evil error reporting.

08:33 <Shinmera> I can't seem to create an example myself though.

08:37 <Shinmera> Yeah, all the barfing strings do contain characters in that range

08:37 <Shinmera> But the char reported as invalid seems... random?

08:49 <luis> It might be the previous character, maybe?

08:49 <Shinmera> If I try to construct the test it reports the correct character as faulty

08:53 <Shinmera> I don't have time to debug this further. The behaviour is too confusing for me to know what to do at this point

08:54 <Shinmera> Ignoring the invalid range in my constructed examples is good enough for now, but it would be better if Slime either replaced or removed invalid characters when sending stuff over, since the current semi-crashing behaviour is far less than ideal.

08:54 <luis> Definitely. Can you open issue with the test case that does fail?

08:55 <luis> *an issue

08:55 <Shinmera> https://github.com/slime/slime/issues/527

08:58 <luis> What Lisp are you using?

08:58 <Shinmera> SBCL

08:58 <Shinmera> I pasted the exact steps to get my error

08:58 <Shinmera> https://github.com/slime/slime/issues/527#issuecomment-530733179

08:59 <luis> OK. Thanks.

08:59 <Shinmera> Hope that helps!