Nested flatten with a custom Enumerable class doesn't work #2767
Description
Input
# typed: true
class A
extend T::Sig
extend T::Generic
include Enumerable
Elem = type_member(fixed: String)
sig { override.params(blk: T.proc.params(e: Elem).void).void }
def each(&blk)
T.unsafe(nil)
end
sig { returns(T::Array[Elem])}
def flatten
T.unsafe(nil)
end
end
def main
a = A.new
b = [A.new, A.new]
T.reveal_type(a.flatten)
T.reveal_type(b.flatten)
endObserved output
Revealed type: T::Array[A]
Expected behavior
Revealed type: T::Array[String]
Flatten is called on subsequent objects of the collection. I'd expect that sorbet know flatten will call flatten in the custom enumerable.
See convo on slack:
https://sorbet-ruby.slack.com/archives/CJL5B3CEN/p1583892614100500