[perl #39249] Can't use literal unicode string as a hash key.

[via RT]

# New Ticket Created by  Will Coleda 
# Please include the string:  [perl #39249]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/rt3/Ticket/Display.html?id=39249 >


The following code:

.sub test
   $P1 = new .Hash
   $P1[unicode:"\u7777"] = 'ok'
   $S1 = $P1[unicode:"\u7777"]
   say $S1
.end

fails to compile. (should print "ok")

$ ./parrot foo.pir
build_key: unknown type 0x10001 on unicode:"\u7777"

Note that the same code works fine if the unicode string is put into  
a string register instead of used as a literal.