Elixir: Formatter do not add parenthesis for the typespec

[yordis]

Environment

• Elixir & Erlang versions (elixir --version): Elixir 1.7.0-dev (77c9d48) (compiled with OTP 20)
• Operating system: MacOS

Current behavior

I ran mix format I am expecting this line https://github.com/straw-hat-team/straw_hat_mailer/blob/224410cf37ee685237bc058c4822361e6b705f4d/lib/straw_hat_mailer/schema/template.ex#L76 do not change

Expected behavior

I am expecting the typespec to be added the parenthesis as Elixir does with the primitive types (so far).

So it would change to

@spec changeset(t(), partial_attrs()) :: Ecto.Changeset.t()

[josevalim]

Elixir formatter cannot change the AST/semantics of the code, otherwise we risk breaking the code. For this reason, we only add parens to remote calls, we cannot add to variables.

I know from context you know it is a spec but the formatter does not have such context.

[yordis]

@josevalim if that is true why does the formatter add the parenthesis when I remove it from Ecto.Changeset.t what does we only add parens to remote calls means? For my personal knowledge, if you dont mind to answer.

[ericmj]

With Ecto.Changeset.t we know it has to be a function call so we can add the parenthesis. For t it can be either a function call or a variable so we could break code if parenthesis are added.

[devonestes]

Parens can't be added there because as it's written now, that t could be a reference to either a function _or_ a variable in that scope. Adding parens could break if it was supposed to be a reference to a variable.

If something is a function call outside of the current scope, you can be sure that it's not a reference to a variable, so you can safely add the parens.