You can let dialyzer know with changing @spec call(Conn.t(), atom()) :: Conn.t()
To @spec call(Conn.t(), atom()) :: no_return() | Conn.t()
Schultzer
NobbZ
no_return | … doesn’t make sense.
Either a function is no_return or it is not. But it can’t be both.
Schultzer
I’m not an expert on dialyzer at all, but in the past when I had dialyzer warnings with any function that could raise then ‘no_return()’ has always worked.
But there might be a specific type that encapsule a function that would raise on error or return a value?
I’m intrested in hearing how you have solved these dialyzer warnings on function no_return?
NobbZ
no_return means, this function will never return.
Never returning means, it will recurse infinitely.
Raising is always allowed, you do not need to annotate it, we are not doing Java here.
Dialyzer will never complain about a raise here or there, as long as it can proove you will return a value of the correct type at least sometimes.
It will complain though, if it does not find a way to properly return a value of the correct type, it will tell you something like “function foo does not have a local return”.
Just adding no_return as one of the possible return types, tells dialyzer “ignore everything else, this function does not return ever”.
So instead of just adding no_return you should think about if that is right, and why dialyzer might think it is that way and then fix the code.
danschultzer
Pow Core Team
What version of ElixirLS are you using? I just tested with the plug and it doesn’t print any dialyzer warning for me (I also ran mix dialyzer just to be sure.). Using ElixirLS 0.2.25.
Kurisu
I’m using the vscode extension and it’s marked ElixirLS v0.5.0.
I’m working in an umbrella project and running mix dyalizer at the root of the umbrealla or in its child app shows:
** (Mix) The task “dyalizer” could not be found
Should I add any dependency?
My initial warning message
Function call/2 has no local return.ElixirLS Dialyzer
is shown only in vscode editor. When compiling the project in terminal and running Phoenix server I don’t see any warning. I have to say also that I just installed the ElixirLs vscode plugin but didn’t add any configuration.
Kurisu
Thank you all for your replies and for your time.
I think the issue has nothing to do with Pow. I just replaced the LoadProfilePlug with another Plug code that does not show any warning in its original context, and the warning remains in the LoadPlugProfile. That is to say no matter the code I put in it, the warning remains. The issue comes probably from the outside of the Plug, maybe because of how I call it? I will be checking that.
I feel really sorry for wasting you some time on this.
Thanks
NobbZ
The LS uses a bundled/vendored version of dialyxir, just to translate errors that have been found by dialyzer into elixir syntax.
If you want to run dialyzer from the terminal on your own, you will need to add the dialyxir package as a :dev dependency to your project.
A “has no local return” is often hard to debug and can require knowledge of the full program context and its libraries. More than often, this errors origin was in a library that had some types of its own wrong, or a NIF-stub was not set up correctly.
Kurisu
Fortunately erasing the .elixir_ls folder and let it be rebuilt made the warning gone. Thanks.
Kurisu
Hello @danschultzer,
The guide on user roles and authorization through a Plug is great for keeping users from accessing restricted pages but sometimes we would want more radical methods. For example in an umbrella project, I don’t want front_app users to be authenticated when trying to login through the admin_app page.
So I added a custom authenticate method to the admin users context:
@doc """
Ensure that only admin can be authenticated
"""
def authenticate(params) do
user = pow_authenticate(params)
case user do
%{role: "admin"} -> user
%{role: "superadmin"} -> user
_ -> nil
end
end
Maybe there is a better/recommended way to achieve this?