Fix compilation error

[ptzz]

Fixes #48.

[maxnordlund]

I also encountered this today, and unfortunately the Travis build fails on python 2. It seems like they may have changed the type with 3.7

[ptzz]

Ah, didn’t check CI results 😕. I’m without computer access for a couple of weeks, anyone feel free to push fixes to this PR meanwhile.

[ptzz]

Turns out I forgot to remove the initial hacky cast solution in the PR. But keeping that (line 48) and removing the rest probably makes CI happy. The cast is probably required anyway to stay compatible with Python < 3.7. The return type of PyUnicode_AsUTF8 did indeed change from char* to const char*.

[maxnordlund]

Can I push to your branch? Or could you give me access to your fork; I could take a stab at it.

[ptzz]

@maxnordlund Sure, did you try? Not sure how it works with permissions, some guy pushed to a PR of mine the other day without me giving explicit permissions. Pushed to my fork that is.

[maxnordlund]

I think that only works for members of the original repo, i.e. nixprime.

[ptzz]

@maxnordlund I’ve sent you a collaborator invite.

[maxnordlund]

Thank you, I've accepted and will try some stuff.

If just the cast won't work, I'm going for the full blown PY_MAJOR_VERSION/PY_MINOR_VERSION conditional compilation changing the signature of PyVimString_AsStringAndSize for ≥ 3.7

[maxnordlund]

Well, that went smoothly. Now it's ready I think, if @nixprime agrees. (Also you can just squash away my commit)

[ptzz]

@maxnordlund 🎉💪👍

[Shougo]

@nixprime Ping. I have encountered the problem today..

[danarnold]

This PR fixes the issue for me with nvim and python 3.7.0-3. Thanks @ptzz and @maxnordlund !