Generics inheritance problem

[firejox]

I think this code should work or not work with meaningful error message

class Foo(T)
end

class Bar(T) < Foo(T)
end

Deque(Foo(Int32)).new.push(Bar(Int32).new)

however, compiler gave this

Error in line 7: instantiating 'Deque(Foo(Int32))#push(Bar(Int32))'

in /usr/lib/crystal/deque.cr:401: instantiating 'increase_capacity()'

    increase_capacity if @size >= @capacity
    ^~~~~~~~~~~~~~~~~

in /usr/lib/crystal/deque.cr:527: instance variable '@buffer' of Deque(Foo(Int32)) must be Pointer(Foo(Int32)), not Pointer(Foo(Int32))

      @buffer = Pointer(T).malloc(@capacity)
      ^~~~~~~

be Pointer(Foo(Int32)), not Pointer(Foo(Int32)) is not really meaningful.

Crystal version

https://carc.in#/r/1ic3
Crystal 0.20.3+2 [929a551]