[perl #116230] [BUG] Role type objects don't trigger the rhs in infix: in Rakudo

[Carl Mäsak]

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<doy> r: role Foo { }; class Bar { has Foo $.foo; method baz { my $foo
= $!foo; my $replacement = Foo.new; say $replacement.defined; say
$foo.defined; $foo //= $replacement; say $foo.defined } }; Bar.new.baz
<p6eval> rakudo 930369: OUTPUT«True␤False␤False␤»
<doy> role type constraints seem to break things
* masak submits rakudobug
<masak> r: role Foo {}; my $x = Foo; $x //= Foo.new; say $x.defined
<p6eval> rakudo 930369: OUTPUT«False␤»
<masak> r: role Foo {}; say Foo.new.defined
<p6eval> rakudo 930369: OUTPUT«True␤»
<masak> yeah. definitely something wrong there.
<masak> r: role Foo {}; my $x = Foo; $x = $x // Foo.new; say $x.defined
<p6eval> rakudo 930369: OUTPUT«False␤»

It is my expectation that when something undefined occurs on the lhs
of the infix:<//> operator, the rhs should be the result.