Fully revert windows support

[jtibshirani]

We added support for Windows in #535. We then partially reverted the change, specifically the parts related to mmap (#706). This was okay because we no longer build for Windows.

This PR fully removes support to avoid being in a partially-implemented state.

[janhartman]

🧹

[Alligator-1]

Oh, no! I need that feature
I use zoekt locally on Windows to search the sources. I discovered it a couple of years ago and am very happy with the experience and speed. But now it turns out I can't use newer versions? What does this mean that Windows is not supported - will it be impossible to compile and run?

Please consider, maybe there is some way to keep zoekt running on windows?

[jtibshirani]

@Alligator-1 could you share what version/ commit of Zoekt you are running? An also the mechanism you use to run locally? I'll see what I can do to make sure things still work for you!

[Alligator-1]

Apparently, this is the version
(I was just following the build instructions, I don't know Go to use the right tool to view the commit hash)
9697031

This version works fine, but periodically I watch for changes and either after enough time has passed, or if I notice any significant useful commits from my point of view - I upgrade, but now I'm afraid that I might stay on some old version if Windows support goes away.... (I'm not really a professional developer, but a hobbyist).

How I use Zoekt:

1. The first thing I do is index the sources (VirtualBox, WINE, open source parts of Windows, FPC, Lazarus) once, and update the index periodically
2. I start webserver (it's in my autoloader)
3. I use the default interface of webserver

that's it, nothing else...

(by the way, I'll ask a question right away, I usually recreate the index again when I update the sources (WINE, for example). And it's a full recreate, I read but didn't fully understand - does zoekt allow to do partial index update over git? if yes - it would make the experience with it more convenient, it would be possible to update indexes more often).

[jtibshirani]

Apparently, this is the version

I see, you were using a version that built for windows, but that used direct file reads instead of mmap (which is considered too slow for serious production usage). I am hesitant to restore support, because it is untested, and not a configuration we run regularly. However, I'm really open to reconsidering this decision if we hear from more Windows users that find Zoekt useful. I'll keep an eye on this PR for comments or reactions.

And it's a full recreate, I read but didn't fully understand - does zoekt allow to do partial index update over git?

You're correct, that's the default behavior. We do have an experimental feature called "delta" indexing" that computes what's changed in the repo, and only updates those files. If you use the zoekt-git-index command, you can test this out by supplying the -delta.

[Alligator-1]

which is considered too slow for serious production usage

So be it, if that's all it is?
As long as it works on Windows at all.
The way it works now for my amount of source code is very fast! Lightning fast! And I'm fine with that...
My only concern now is this Pull Request - does it mean that now that it's merged- I can't compile and use the new version of zoekt natively on a windows machine?