[perl #77586] [BUG] Assigning to a hash with the same hash in the rhs of the assignment causes the hash to become empty in Rakudo

[Carl Mäsak]

# New Ticket Created by  "Carl Mäsak" 
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<masak> rakudo: my %h = 1 => "foo", 2 => "bar", 3 => "foo"; %h = grep
{ .value ne "bar" }, %h.pairs; say %h.perl
<p6eval> rakudo f8e959: OUTPUT«{}␤»
<masak> anyone but me thinks that the result should contain two pairs?
<patrickas> rakudo: my %h = 1 => "foo", 2 => "bar", 3 => "foo"; my %n
= grep { .value ne "bar" }, %h.pairs; say %n.perl
<p6eval> rakudo f8e959: OUTPUT«{"1" => "foo", "3" => "foo"}␤»
* masak submits rakudobug
<masak> patrickas++ # workaround
<masak> rakudo: my %h = 1 => "foo"; %h = %h; say %h.perl
<p6eval> rakudo f8e959: OUTPUT«{}␤»
<masak> rakudo: my %h = 1 => "foo"; my %n = %h; say %n.perl
<p6eval> rakudo f8e959: OUTPUT«{"1" => "foo"}␤»
<patrickas> duh!
<masak> doubleplusungood.
<patrickas> rakudo: my %h = 1 => "foo"; %h = %h.clone; say %h.perl;
<p6eval> rakudo f8e959: OUTPUT«{"1" => "foo"}␤»
<patrickas> might be slightly nicer than creating a named temporary
variable as a workaround
<masak> indeed.