Fix file+noindex URI usage on Windows

[jasagredo]

This PR fixes the parsing of URIs for file+noindex repositories when using Windows paths. As suggested by @phadej in #10703 we now use (and specify in the docs) //./C:/... paths on Windows.

QA

In Windows, one can now specify //./ paths in file+noindex repositories. To check, create a simple package, then cabal sdist, move the tar.gz to some directory and in a different project declare the following stanza:

repository my-local-repo
  url: file+noindex:////./C:/path/to/repo

It might still fail because of #9891

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[jasagredo]

Notice this was broken on Windows #10095 (comment), see how the paths in the output do not have a C: component, because of what I described in the first code block of #10703

[ulysses4ever]

Thanks! I wonder if we can pull in some of Andrea’s PRs after this fix…

[ulysses4ever]

Perhaps just inline it [asPosixPath]

I'd suggest not to inline it. I'd definitely prefer reading unrelated code that calls a function like that rather than seeing the list comprehension.

[mergify]

This pull request has been removed from the queue for the following reason: pull request dequeued.

Pull request #10728 has been dequeued. Branch protection setting 'linear history' conflicts with Mergify configuration. Branch protection setting 'linear history' works only if merge_method: squash or merge_method: rebase.

You should look at the reason for the failure and decide if the pull request needs to be fixed or if you want to requeue it.

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[jasagredo]

@hasufell pointed out that NT namespace doesn't work as I said in my comment above.

My goal here is to provide some "standard" way of declaring filepaths for a file+noindex repository on Windows. So far we have the following:

• file+noindex://C:/foo results in C: being parsed as the Auth of the URI
• file+noindex:///C:/foo results in the path /C:/foo which cannot be used even if normalized
• file+noindex:////?/C:/foo results in ?/C:/foo being considered the query of the URI
• file+noindex:////./C:/foo works as expected after normalization to \\.\C:\foo or (as Path prefixed by \\.\ is not normalised on Windows filepath#247 shows) \\.\C:/foo.

The NT mention above was just an experiment I tried to run, motivated by what I saw in the GHC User Guide, but it seems it was a misuse on my side from what Julian points out.

To be clear, I don't want to use the NT namespace in particular. I just want to use the simplest option available, which seems to be //./.

[ulysses4ever]

@mergify refresh

[mergify]

refresh

✅ Pull request refreshed

[mergify]

This pull request has been removed from the queue for the following reason: pull request dequeued.

Pull request #10728 has been dequeued. The pull request rule doesn't match anymore. The following conditions don't match anymore:

• label=squash+merge me

You should look at the reason for the failure and decide if the pull request needs to be fixed or if you want to requeue it.

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[ulysses4ever]

@Mergifyio requeue

[mergify]

requeue

☑️ This pull request is already queued

[ulysses4ever]

mergify is at it again: merging before the CI finishes. We really should revert the .skip workflows sorcery. Correction: CI was green, so the bot did the right thing. Apologies on putting on the labels prematurely. I was under impression that it's done.