[Self-Filed] Windows Support

[cpsauer]

This is a tracking issue for Windows builds, linked to from the README.

If you'd like support for Windows, we'd love your help. It should be a fair bit easier to add support than to do yourself from scratch, we'll help guide, and then your code will work across platforms for free. Plus, you'll be helping everyone out. Please comment here, helping ensure people don't duplicate efforts.

[cpsauer]

Sketch of how to implement:

CPR should just work out of the box, so the focus will be on getting configuration for libCURL. You'll just need to motify curl.BUILD, referencing the guiding comments therein.

In more detail:

• Building from source: My read is that curl pretty much just auto-configures on windows, adding config-win32.h automatically, so mostly you'll just want to add a select on "@platforms//os:windows" that omits everything except that first batch of local_defines.
• Please link to system SSL (USE_SCHANNEL)--and let's omit zlib, at least in the first PR, unless zlib is bundled with the OS and I didn't realize it.
  • XP seems very dead, so I'm not so worried about the "Legacy Windows and SSL" section of the curl docs.
  • Please run some quick SSL tests against https://badssl.com/, just to make sure everything's working correctly.
• Some alternatives: You could also link against a prebuilt windows curl if you want, pulling it down. Alternatively if you think we should be depending on, e.g., winget or some other means of getting dependencies that could be depended on when distributing and installing code compiled with this rule, then we can use that. Or, if libcurl is preinstalled far enough back on windows, we should use that.

[rynewang]

any updates on this one?

[cpsauer]

I'm afraid I don't have the bandwidth to knock this one out right now, but that needn't stop you! I'd be happy to take a good PR--outline above