[perl #125598] [BUG] $/ does not bind correctly in the right-hand side of s/// inside a for loop in Rakudo

[Carl Mäsak]

# New Ticket Created by  "Carl Mäsak" 
# Please include the string:  [perl #125598]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=125598 >


<lucasb> m: my $x = 'a1'; $x ~~ s/(\d+)/<$0>/; say $x
<camelia> rakudo-moar 58a5ed: OUTPUT«a<1>␤»
<lucasb> m: for 1 { my $x = 'a1'; $x ~~ s/(\d+)/<$0>/; say $x }
<camelia> rakudo-moar 58a5ed: OUTPUT«Use of Nil in string context  in
code  at /tmp/SOTPBUyxHF:1␤a<>␤»
* masak submits rakudobug
<masak> lucasb: clearly that should work. thanks for finding it.
<masak> m: my $s = "OH 819"; $s ~~ s:g/(\d)/{chr(64 + $0)}/; say $s
<camelia> rakudo-moar 58a5ed: OUTPUT«OH HAI␤»
<masak> m: my $s = "OH 819"; for $s { s:g/(\d)/{chr(64 + $0)}/; .say }
<camelia> rakudo-moar 58a5ed: OUTPUT«Use of Nil in numeric context  in
block  at /tmp/4I0l1xSFeV:1␤Use of Nil in numeric context  in block
at /tmp/4I0l1xSFeV:1␤Use of Nil in numeric context  in block  at
/tmp/4I0l1xSFeV:1␤OH @@@␤»

So, two cases of the same code, with and without a surrounding for
loop block. All these match, but in the presence of the for loop, $/
is Nil instead of the appropriate match object.