tim2CF / dialyzer_bug

DialyzerBug

Software versions

MacOS 10.15.4
Erlang/OTP 22 [erts-10.6.4]
Elixir (1.10.1)
Dialyxir 1.0.0

To reproduce bug on your machine

git clone [e-mail]:tim2CF/dialyzer_bug.git
cd ./dialyzer_bug
mix deps.get
mix test
mix dialyzer

and you will see output which is caused by this simple function (which works fine in tests)

def hello do
  x =
    quote do
      Map.new()
      |> Map.put(:hello, :world)
    end

  {%{hello: world}, _} = Code.eval_quoted(x)
  world
end

error is not expected and type which Dialyzer suggests is weird

lib/dialyzer_bug.ex:15:no_return
Function hello/0 has no local return.
________________________________________________________________________________
lib/dialyzer_bug.ex:22:pattern_match
The pattern can never match the type.

Pattern:
{%{:hello => _world}, _}

Type:
{atom() | [any()] | number() | {_, _, _, _}, [{atom() | tuple(), _}]}

________________________________________________________________________________
done (warnings were emitted)
Halting VM with exit status 2

spec of eval_quoted is pretty straightforward and don't contain this type

@type binding :: [{atom() | tuple(), any}]
@spec eval_quoted(Macro.t(), binding, Macro.Env.t() | keyword) :: {term, binding}