[perl #123660] Confusion when using $_ as default

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# New Ticket Created by  Elizabeth Mattijsen 
# Please include the string:  [perl #123660]
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# <URL: https://rt.perl.org/Ticket/Display.html?id=123660 >


[11:17:08]  <jnthn>     And here's a nice bug:
[11:17:10]  <lizmat>    m: sub a($a = CALLER::CALLER::<$_>) { say $a }; $_ = 
"foo"; a   # indeed
[11:17:10]  <+camelia>  rakudo-moar cd87c4: OUTPUT«foo␤»
[11:17:14]  <jnthn>     m:  sub foo($a = CALLER::CALLER::<$_>) { say $a }; 
given 42 { foo(1); foo() }
[11:17:14]  <+camelia>  rakudo-moar cd87c4: OUTPUT«1␤No such method 'dynamic' 
for invocant of type 'Int'␤  in method at_key at src/gen/m-CORE.setting:11131␤  
in sub postcircumfix:<{ }> at src/gen/m-CORE.setting:3090␤  in sub foo at 
/tmp/MgALuGqWgZ:1␤  in block <unit> at /tmp/MgALuGqWgZ:1␤␤»
[11:18:09]  <lizmat>    hehe
[11:18:17]  <lizmat>    rakudobuggable ?
[11:18:20]  <jnthn>     Yeah