Detailed description in this elixir forum post
Demostrate that dialyxir gives false positive result for Elixir anonymouse fuction type spec, but report Erlang file issue correctly.
run
mix dialyzer
Environment:
dialixir: 1.0.0-rc4 Elixir: 1.8.0-otp-21 (same behavior observed from 1.7.4) Erlang: 21.2.4 (same behavoir observed from 21.1.1) macOS 10.14.2