Analysis server doesn't start up correctly on Windows

[DanTup]

On my Windows PC using a bleeding edge SDK (or running server from source), the server fails to start up correctly from VS Code and no language functionality is available.

I'm still investigating, but it seems to be getting stuck waiting for watchers to become ready while building context roots:

There's a suspicious path format in the resource being watched which makes me suspicious about some recent changes I made to use path contexts. I also see this in some of the JSON:

{"scopeUri"::"file::///C::/C::/Dev/Test%20Projects/dart_application_3

This must be a recent break - although I don't know why no bots are failing (it's possible this is isolated to my machine, but that would be odd too).

(@bwilkerson FYI - I'm looking into this and will post back shortly)

[DanTup]

Seems like pathContext.fromUri doesn't like encoded colons for the drive letter:

Future<void> test_danny() async {
  final fileUris = [
    'file:///C%3A/Dev/Test%20Projects/dart_application_3',
    'file:///C:/Dev/Test%20Projects/dart_application_3'
  ];
  for (final fileUri in fileUris) {
    final path1 = Uri.parse(fileUri).toFilePath();
    final path2 = pathContext.fromUri(fileUri);
    print('Uri.parse($fileUri).toFilePath():\n    $path1');
    print('pathContext.fromUri($fileUri):\n    $path2');
  }
}

Uri.parse(file:///C%3A/Dev/Test%20Projects/dart_application_3).toFilePath():
    C:\Dev\Test Projects\dart_application_3

pathContext.fromUri(file:///C%3A/Dev/Test%20Projects/dart_application_3):
    \C:\Dev\Test Projects\dart_application_3

Uri.parse(file:///C:/Dev/Test%20Projects/dart_application_3).toFilePath():
    C:\Dev\Test Projects\dart_application_3

pathContext.fromUri(file:///C:/Dev/Test%20Projects/dart_application_3):
    C:\Dev\Test Projects\dart_application_3

Probably the reason no tests failed is that we're not encoding the colon, but VS Code is. I'm struggling to find info on whether it's valid or not. If it is, package:path should handle it. If it's not, the LSP client

[DanTup]

I'm going to partially revert 77799f6. The whole change doesn't revert cleanly, and we only need to not use pathContext.fromUri() in the LSP server for now. A smaller revert will be easier to re-land later if we can address the issue in package:path or similar later.

[DanTup]

https://dart-review.googlesource.com/c/sdk/+/315260 reverts use of pathContext.fromUri() in LSP, and https://dart-review.googlesource.com/c/sdk/+/315280 adds some tests that use VS Code's path formatting.

I'll try and find some concrete info on whether the escaped colon is valid or not (if it is, we need to fix package:path, and if it's not, we need the VS Code LSP client fixing).