clang::Cursor::ret_type should return an Option<Cursor>

[fitzgen]

Right now it always returns a Cursor but it makes an FFI call to clang_Cursor_getCursorResultType which is only valid if the cursor's referent is a function or method declarations and calls:

http://clang.llvm.org/doxygen/group__CINDEX__TYPES.html#ga6995a2d6352e7136868574b299005a63

This only returns a valid type if the cursor refers to a function or method.

We should check whether the cursor referent is a valid function/method call/decl kind, and if it is not, we should return None. This will be one less foot gun.

I can mentor whoever would like to pick up this bug.

[highfive]

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

[Natim]

I am going to give it a try.

[Natim]

clang::Cursor::ret_type should return an Option

I think it should return an Option<Type> instead of a Type correct?

[wafflespeanut]

Precisely!

[Natim]

Well I am kind of puzzled that the tests still pass 😞