`__info__(:struct)` type missing `required` key

[lukaszsamson]

Existing issue

• I have searched existing issues and could not find a duplicate.

Elixir and Erlang/OTP versions

Erlang/OTP 28 [erts-16.4.0.1] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit]

Elixir 1.20.0 (compiled with Erlang/OTP 28)

Operating system

any

Current behavior

Repro:

defmodule A do
        def foo do
            [first | _] = URI.__info__(:struct)
            Map.get(first, :required)
        end
        end
warning: incompatible types given to Map.get/2:

    Map.get(first, :required)

the map:

    %{default: if_set(term()), field: atom()}

does not have all required keys:

    :required

therefore this function will always return nil

where "first" was given the type:

    # type: %{default: if_set(term()), field: atom()}
    # from: iex:6
    [first | _] = URI.__info__(:struct)

└─ iex:7: A.foo/0

Yet it's easy to show the key exists and the code works

[first | _] = URI.__info__(:struct)
[
  %{default: nil, field: :scheme, required: false},
  %{default: nil, field: :authority, required: false},
  %{default: nil, field: :userinfo, required: false},
  %{default: nil, field: :host, required: false},
  %{default: nil, field: :port, required: false},
  %{default: nil, field: :path, required: false},
  %{default: nil, field: :query, required: false},
  %{default: nil, field: :fragment, required: false}
]
iex(3)>     Map.get(first, :required)
false

Expected behavior

Correct type inferred

[josevalim]

The key is deprecated, so it was not added to the types so folks migrate away from it. I will make sure this is clear in the docs.

[lukaszsamson]

It was added quite recently in #14616. BTW even if deprecated I think it should be included in the type

[lukaszsamson]

Also per your comment #14500 (comment) it is the official way of getting enforced structures fields in runtime

[josevalim]

You are correct. I arrived to the same conclusion. :) Closing in favor of the PR!