Wrong return types in the @specs are ignored?

[matteo-gheri-pocketworks]

Environment

• Elixir & Erlang/OTP versions (elixir --version): Erlang/OTP 25 and Elixir 1.14.0

• Which version of Dialyxir are you using? (cat mix.lock | grep dialyxir): 1.4.3

  Current behavior

  Hello, just wanted to mention something I noticed. I've added a screenshot for simplicity. I got an error message in the case statement when test_3 calls test_2, it says The pattern can never match the type. Pattern: :error Type: :valid. But, the weird thing is, test_2's spec includes :error too, although been wrong. It's easy to spot the issue here, but in real-world scenario, it's trickier (or at least has been for me 😅) to figure out with the current error message.

Expected behavior

Highlight the error in function 2 suggesting the wrong spec?

[Sinc63]

I don't think I mind having a spec that has extra bits. I'd be more worried about the fact that test_2 can clearly return :invalid and there is no complaint about that in regards to its spec or test_3's behaviour.

[jeremyjh]

This is a question about dialyzer, which isn't part of this project. This project is just an Elixir integration with dialyzer. If I knew the answer here I'd tell you; I suspect there is a warning flag you can enable to get the desired behavior; the ones we enable by default are very basic. For help understanding the counter-intuitive behaviors of Dialyzer I recommend asking on the Elixir forums.