clang::Type::arg_types should return Option<Vec<Type>>

[fitzgen]

arg_types makes FFI calls that are only valid if this type is a function type. We should check whether or not this type is a function type, and if it is not, then return None. If it is, we should proceed with the FFI calls and return Some.

This will make it so that every caller doesn't have to remember to do the check, which removes a foot gun if they forget.

I can mentor whoever would like to work on this bug.

[highfive]

Please make a comment here if you intend to work on this issue. Thank you!

[Kiblyn11]

Hi, can I work on this ?

[fitzgen]

Yep! Let me know if you run into any roadblocks or have questions or anything :)

[Kiblyn11]

Sure :).
Actually I have 2 questions :

• To detect if the cursor is a function I think about using clang_isFunctionInlined, any advice on that one ?
• I would like to add a unit test for this but I don't really understand the test structure in this project. Where could I add a test for arg_types method ?

Cheers

[fitzgen]

It might actually be easier to always make the FFI call and then check the result for validity.

http://clang.llvm.org/doxygen/group__CINDEX__TYPES.html#ga705e1a4ed7c7595606fc30ed5d2a6b5a

If a non-function type is passed in, -1 is returned.

You can check if the returned value for the number of args is -1, and if it is, then return None, otherwise proceed getting each argument type.

As for unit tests, unfortunately this particular code isn't setup great for unit tests, and adding new ones won't be straight forward. I suggest just ensuring that the existing integration test suite is passing (see CONTRIBUTING.md for details).

Hope that helps!

[Kiblyn11]

Thanks for your help !

I updated the code to do so, everything seems alright at compilation, unit tests are passing.
But as I cant add unit test I dont know how to test that piece of code. :s

[fitzgen]

Great! \o/

But as I cant add unit test I dont know how to test that piece of code. :s

In this case, I think it is fine to go ahead and open a pull request without any unit tests specific to this issue.