findInstancesDirViaCLSID

    fn findInstancesDirViaCLSID(gpa: Allocator, io: Io, registry: *Registry) error{ OutOfMemory, PathNotFound }!Dir {
        const setup_configuration_clsid = "{177f0c4a-1cd3-4de7-a32c-71dbbb9fa36d}";

        // HKEY_CLASSES_ROOT is not a single key but instead a combination of
        // HKCU\Software\Classes and HKLM\Software\Classes with HKCU taking precedent
        // https://learn.microsoft.com/en-us/windows/win32/sysinfo/hkey-classes-root-key
        //
        // Instead of a CLASSES_ROOT abstraction, we emulate the behavior with a more
        // general abstraction, which also means we need to include `Classes` in the path since
        // we're starting from the `Software` keys instead of the "classes root".
        //
        // The advapi32 APIs with `HKEY_CLASSES_ROOT` go through `\REGISTRY\USER\<SID>_Classes`
        // instead of `\REGISTRY\USER\<SID>\Software\Classes`, but we go through the latter
        // because it allows us to take advantage of `RtlOpenCurrentUser` to avoid needing to implement
        // the logic for getting the current user registry path, and it appears that the two keys are
        // effectively equivalent. Further investigation of the relationship of these keys would probably
        // be beneficial, though.
        const setup_config_key = registry.tryOpenSoftwareKeyWithPrecedence(&.{
            .{ .root = .current_user },
            .{ .root = .local_machine },
        }, L("Classes\\CLSID\\" ++ setup_configuration_clsid)) catch |err| switch (err) {
            error.KeyNotFound => return error.PathNotFound,
        };
        defer setup_config_key.close();

        const inproc_server = setup_config_key.open(L("InprocServer32")) catch return error.PathNotFound;
        const dll_path = inproc_server.getString(gpa, .default, .wtf8) catch |err| switch (err) {
            error.NotAString,
            error.ValueNameNotFound,
            error.StringNotFound,
            => return error.PathNotFound,

            error.OutOfMemory => |e| return e,
        };
        defer gpa.free(dll_path);

        if (!std.fs.path.isAbsolute(dll_path)) return error.PathNotFound;

        var path_it = std.fs.path.componentIterator(dll_path);
        // the .dll filename
        _ = path_it.last();
        const root_path = while (path_it.previous()) |dir_component| {
            if (std.ascii.eqlIgnoreCase(dir_component.name, "VisualStudio")) {
                break dir_component.path;
            }
        } else {
            return error.PathNotFound;
        };

        const instances_path = try std.fs.path.join(gpa, &.{ root_path, "Packages", "_Instances" });
        defer gpa.free(instances_path);

        return Dir.openDirAbsolute(io, instances_path, .{ .iterate = true }) catch return error.PathNotFound;
    }