Recursive alias does not match non generic subclass of generic type

[jeromegn]

(Was: Adding a K => V to a Hash subclass is not possible with certain types)

In short: With a subclassed (and permissive of many types) Hash, it's not always possible to add certain types of values to it.

Demonstation: http://play.crystal-lang.org/#/r/fbe

I lack the words to explain it better so hopefully the linked demo is self-explanatory.

Is this a bug, a feature or a missing feature?

[pgkos]

A similar issue:

ary = [] of Array(String | Char) | Array(Int32 | Float64)
ary << ["abc", 'd']  # works
ary << ["abc", "def"]  # does not compile

but this works:

ary = [] of Array(String | Char)
ary << ["abc", 'd']  # works
ary << ["abc", "def"]  # also works

[jeromegn]

Something is odd. I just realized I'm able to assign a key to a Array(BSON::Document) fine when I generate the document from the bson source.

Essentially, this this value of the document will make an Array(BSON::Document | String | Int32 | Bool | BSON::ObjectId). Later on, it'll be inserted in the document.

I'm not sure that would suddenly work...

I created a new playground code example http://play.crystal-lang.org/#/r/fix which shows how it works if the array's type is specified beforehand.

[asterite]

Closed in favor of #2665