Pretty Printing Spec With When

[jeremyjh]

This code fails on dialyxir master. It looks like we just need to keep a space after "when" in the spec we pass to the code formatter from pretty_print_contract, Code.format_string! is complaining about 'ok'whenone.

defmodule WhatTheSpec do
  @type key :: atom()
  @type transaction :: map()

  def put(_, _, _ \\ nil)

  @spec put(one, key(), any()) :: transaction() when one: transaction()
  def put(t, _, _) when is_map(t), do: t

  @spec put(one, any(), Keyword.t()) :: :ok when one: key()
  def put(_, _, _), do: :ok

  @spec put_foo(any()) :: :ok
  def put_foo(value) do
    put(:foo, value, nil) # note the explicit nil here
  end
end

'(one,key(),any()) -> transaction() when one :: transaction();(one,any(),\'Elixir.Keyword\':t()) -> \'ok\' when one :: key()'
%SyntaxError{
  description: "syntax error before: whenone",
  file: "nofile",
  line: 1
}
** (throw) {:error, :formatting, "@spec a(:one, any(), Keyword.t()) :: 'ok'whenone :: key()\ndef a() do\n  :ok\nend\n"}

[asummers]

Yep that looks like a bug!

[asummers]

It's a little more complicated than just a missing space.

https://github.com/asummers/erlex/blob/master/lib/erlex.ex#L133

That guy breaks apart the different heads and calls do_pretty_print_contract which is not when aware. That needs to call back into pretty_print_contract which would be able to differentiate properly. Good find, Won't have time to pick this up til later, but that's about what the fix is gonna look like.

[asummers]

Much deeper than I thought. When lexing we get the following:

[
  {:"(", 1},
  {:atom_part, 1, 'o'},
  {:atom_part, 1, 'n'},
  {:atom_part, 1, 'e'},
  {:",", 1},
  {:atom_part, 1, 'a'},
  {:atom_part, 1, 'n'},
  {:atom_part, 1, 'y'},
  {:"(", 1},
  {:")", 1},
  {:",", 1},
  {:atom_full, 1, '\'Elixir.Keyword\''},
  {:":", 1},
  {:atom_part, 1, 't'},
  {:"(", 1},
  {:")", 1},
  {:")", 1},
  {:->, 1},
  {:atom_full, 1, '\'ok\''},
  {:atom_part, 1, 'w'},
  {:atom_part, 1, 'h'},
  {:atom_part, 1, 'e'},
  {:atom_part, 1, 'n'},
  {:atom_part, 1, 'o'},
  {:atom_part, 1, 'n'},
  {:atom_part, 1, 'e'},
  {:::, 1},
  {:atom_part, 1, 'k'},
  {:atom_part, 1, 'e'},
  {:atom_part, 1, 'y'},
  {:"(", 1},
  {:")", 1}
]

Note that that when is just in the middle there. That's because of this line in the lexer: {WHITESPACE} : skip_token.. This is going to be tricky to solve.