m := module.Version{Path: path, Version: vers}
		return moduleInfo(ctx, nil, m, 0, nil)
	}

	rs := LoadModFile(ctx)

	var (
		v  string
		ok bool
	)
	if rs.pruning == pruned {
		v, ok = rs.rootSelected(path)
	}
	if !ok {
		mg, err := rs.Graph(ctx)
		if err != nil {
			base.Fatal(err)
		}
		v = mg.Selected(path)
	}

	if v == "none" {
		return &modinfo.ModulePublic{
			Path: path,

		for _, m := range mustSelect {
			if m.Version != "none" && !MainModules.Contains(m.Path) {
				rootPaths = append(rootPaths, m.Path)
			}
		}

		for _, m := range roots {
			if v, ok := rs.rootSelected(m.Path); ok && (v == m.Version || rs.direct[m.Path]) {
				// m.Path was formerly a root, and either its version hasn't changed or
				// we believe that it provides a package directly imported by a package

			if gover.IsToolchain(prefix) {
				// Do not use the synthetic "go" module for "go/ast".
				continue
			}
			var (
				v  string
				ok bool
			)
			if mg == nil {
				v, ok = rs.rootSelected(prefix)
			} else {
				v, ok = mg.Selected(prefix), true
			}
			if !ok || v == "none" {
				continue
			}
			m := module.Version{Path: prefix, Version: v}

			root, isLocal, err := fetch(ctx, m)