[perl #126756] Segfault on single utf8-c8 synthetic

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# New Ticket Created by  Elizabeth Mattijsen 
# Please include the string:  [perl #126756]
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# <URL: https://rt.perl.org/Ticket/Display.html?id=126756 >


[15:04:37]  <lizmat>    m: Buf.new(0xFE).decode("utf8-c8")   # jnthn might find 
this interesting
[15:04:38]  <+camelia>  rakudo-moar 6a45fe: OUTPUT«(signal SEGV)»
[15:08:24]  <jnthn>     lizmat: Uh, yes...wtf...
[15:08:30]  <jnthn>     lizmat: Please RT it

I think it’s related to the fact that it starts with a synthetic, because:

$ 6 'say Buf.new(0xFE,ord(“A”)).decode("utf8-c8")'
Segmentation fault: 11

whereas if it starts with a non-synthetic:

$ 6 'say Buf.new(ord("A"),0xFE).decode("utf8-c8")'
A􏿽xF



Liz