[perl #58030] Named parameter passing errors on subs with optional parameters

[mhelix]

# New Ticket Created by  "mhelix" 
# Please include the string:  [perl #58030]
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# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=58030 >


Passing PMCs as named arguments fails when the called sub accepts optional 
positional
arguments unless all optional arguments are passed. On my tests this bug only
affected PMC arguments. Passing an int, float or string works flawlessly.

Code that shows the problem:

.sub main :main
    load_bytecode 'dumper.pbc'

    'foo'('works flawlessly' :named('key'))
    $P0 = new 'String'
    $P0 = "it won't work now"
    'foo'($P0 :named('key')) # Fails. Key is 'null'
.end

.sub 'foo'
    .param pmc unused :optional
    .param int has_unused :opt_flag
    .param pmc key :named('key')

    '_dumper' (key, 'key')
.end

The output is

"key" => "works flawlessly"
"key" => null