Errors on Parametrized Types

[hickscorp]

From Ecto.Changeset, there is a t() defined such as:

  @type t(data_type) :: %Changeset{valid?: boolean(),
                        ...
                        data: data_type,
                        ...
                        types: nil | %{atom => Ecto.Type.t}}

In our behaviour, we have something like:

  @type user_changeset :: Ecto.Changeset.t(User.t())

  @callback password_operation(user_changeset) :: user_changeset
  @callback password_operation(user_changeset, attrs :: map) :: user_changeset

In our implementation:

  @type user_changeset :: Ecto.Changeset.t(User.t())
  @impl CredentialsHelper
  @spec password_operation(user_changeset) :: user_changeset
  @spec password_operation(user_changeset, map) :: user_changeset
  def password_operation(cs, attrs \\ %{}),
    do: ...

When trying to stub or expect, Hammox raises:

     ** (FunctionClauseError) no function clause matching in Hammox.TypeEngine.match_type/2

     The following arguments were given to Hammox.TypeEngine.match_type/2:
     
         # 1
         nil
     
         # 2
         {:var, 282, :data_type}

Note: we tried every possible combination of typing here - directly Ecto.Changeset.t, Ecto.Changeset.t(any) etc. Only replacing the changeset type by any on the behaviour seems to fix the problem.

[msz]

Hi, thank you for reporting this!

Are you using the latest version? We had #16 which looks like the same problem, and the fix for it was shipped in v0.2.1.

[hickscorp]

No, unfortunately it still doesn't work. We're on v0.2.3.

In our behaviour, all of these fail:

@type changeset :: Ecto.Changeset.t()
@type changeset :: Ecto.Changeset.t(any)
@type changeset :: Ecto.Changeset.t(User.t())

But what is very interesting is that this works:

@type changeset :: %Ecto.Changeset{data: User.t()}

[msz]

Reproduced this on my side. Will fix.