class Foo; end
module TestInterface
abstract def add(foo : Foo) : Foo
abstract def add(bar : T) : Nil forall T
end
class Test
include TestInterface
def add(foo : Foo) : Foo
foo
end
def add(bar : T) : Nil forall T
end
end
t = Test.new
pp t.add Foo.new
pp t.add 123
It fails to compile due to:
11 | def add(foo : Foo) : Foo
^--
Error: this method must return Nil, which is the return type of the overridden method TestInterface#add(bar : T) forall T, or a subtype of it, not Foo
I also tried with -Dpreview_overload_order which resulted in the same error.
It seems the abstract def checker thinks the overload with the explicit type is overriding the free var overload, instead of treating them separately.
I was able to work around this for now by defining the free var method in the interface as:
def add(bar : T) : Nil forall T
{% @type.raise "abstract `def TestInterface#add(bar : T) : Nil forall T` must be implemented by #{@type}" %}
end
Given the following code:
It fails to compile due to:
I also tried with
-Dpreview_overload_order
which resulted in the same error.It seems the abstract def checker thinks the overload with the explicit type is overriding the free var overload, instead of treating them separately.
I was able to work around this for now by defining the free var method in the interface as:
Which works for now :shrug:.