Confusing type warning when checking `with true <- x in []`

[novaugust]

Existing issue

• I have searched existing issues and could not find a duplicate.

Elixir and Erlang/OTP versions

Erlang/OTP 28 [erts-16.3] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit]

Elixir 1.20.0-rc.5 (862ff78) (compiled with Erlang/OTP 28)

Operating system

macos

Current behavior

the following code emits a type warning in 1.20 when @attr is an empty list.

defmodule A do 
  @attr Application.compile_env(:my_app, :my_key)

        def foo do
          with true <- :a in @attr, do: :ok
        end
end

presumably due to compiler optimization, the type warning code doesn't look like the written code (simplified repro below)

iex(1)> defmodule C do
        def foo do
        with true <- :a in [], do: :ok
        end
        end
warning: the following pattern will never match:

    true <-
      (
        _ = :a
        false
      )

because the right-hand side has type:

    false

└─ iex:3: C.foo/0

Expected behavior

the pattern referenced should match the code to some degree to help developers know they're fixing the right bit

[sabiwara]

(removed the issue to "Confusing" because "opaque type" was misleading)