defmodule A do
  def x() do
    Meeseeks.parse("<div id=main><p>Hello, Meeseeks!</p></div>")
  end
end

This gives me this error:

The call:
Meeseeks.parse(<<_::336>>)

will never return since it differs in arguments with
positions 1 from the success typing arguments:

(
  [
    binary()
    | {:comment, binary()}
    | {:pi, binary()}
    | {:pi | binary(), binary() | [{_, _}], binary() | [any()]}
    | {:doctype, binary(), binary(), binary()}
  ]
  | {:comment, binary()}
  | {:pi, binary()}
  | {:pi | binary(), binary() | [{binary(), binary()}], binary() | [any()]}
  | {:doctype, binary(), binary(), binary()}
)

When the specs for Meeseeks.parse is @spec parse(Parser.source()) :: Document.t() | {:error, Error.t()} with Parser.source() being @type source :: String.t() | TupleTree.t() and then TupleTree.t() being

  @type comment :: {:comment, String.t()}
  @type doctype :: {:doctype, String.t(), String.t(), String.t()}
  @type element :: {String.t(), [{String.t(), String.t()}], [node_t]}
  @type processing_instruction ::
          {:pi, String.t()}
          | {:pi, String.t(), [{String.t(), String.t()}]}
          | {:pi, String.t(), String.t()}
  @type text :: String.t()
  @type node_t :: comment | doctype | element | processing_instruction | text
  @type t :: node_t | [node_t]

Dialyxir and Dialyzer helped ma lot, but I don’t understand what’s wrong with those specs, or is it bug with tools rather.

If source :: String.t() | TupleTree.t() or source :: binary() | TupleTree.t() then call Meeseeks.parse(<<_::336>>) where <<_::336>> is binary should satisfy those specs. Right?

Beside, even when dialyxir/dialyzer says [...] will never return since [...] actually when run always returns and simply works OK.