Elixir: :erlang.map_get unnecessary compile warning in guard

[vans163]

Erlang/OTP 23 [RELEASE CANDIDATE 3] [erts-10.7.1] [source-9a6e292336] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Interactive Elixir (1.11.0-dev) - press Ctrl+C to exit (type h() ENTER for help)

This warning happens when using two :erlang.map_get.

Only happens when using mix compile, pasting this code into shell will not trigger a warning.

defmodule Test do
  def test(map) when :erlang.map_get(map,:a) < :erlang.map_get(map,:b) do
    map
  end
  def test(map) do
    map
  end
end

warning: incompatible types:

    :a !~ %{}

in expression:

    :erlang.map_get(map, :a)

Conflict found at
  lib/test.ex:2: Test.test/1

[ericmj]

The warning is correct, you have the arguments flipped. It should be :erlang.map_get(:a, map).

[vans163]

Ah right, lol. Would it be then be an issue the warning is not triggered if copy+pasting the code into REPL?

[ericmj]

No, all warnings are not emitted in the REPL. Some checks are only be performed when code is compiled with the parallel compiler which is not the case for the shell.

[vans163]

Thanks I am closing this sorry for my silly mistake.