This change fixes the bug described in https://bugs.ruby-lang.org/issues/17880.
Checking `ractor_shareable_p` will cause the method to call back into
Ruby. Anything calling this method can't be a leaf instruction,
otherwise it could crash. By adding `attr bool leaf = false` we no
longer crash because it marks the function as not a leaf.
Here's a simplified reproduction script:
```ruby
require "set"
class Id
attr_reader :db_id
def initialize(db_id)
@db_id = db_id
end
def ==(other)
other.class == self.class && other.db_id == db_id
end
alias_method :eql?, :==
def hash
10
end
def <=>(other)
db_id <=> other.db_id if other.is_a?(self.class)
end
end
class Namespace
IDS = Set[
Id.new(1).freeze,
Id.new(2).freeze,
Id.new(3).freeze,
Id.new(4).freeze,
].freeze
class << self
def test?(id)
IDS.include?(id)
end
end
end
p Namespace.test?(Id.new(1))
p Namespace.test?(Id.new(5))
```
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
