// resolution. tok is used to format position in error messages.
func resolveFile(file *ast.File, handle *token.File, declErr func(token.Pos, string)) {
	pkgScope := ast.NewScope(nil)
	r := &resolver{
		handle:   handle,
		declErr:  declErr,
		topScope: pkgScope,
		pkgScope: pkgScope,
		depth:    1,
	}

	for _, decl := range file.Decls {
		ast.Walk(r, decl)
	}

	r.closeScope()

func (r *reader) ident(marker pkgbits.SyncMarker) (*types.Package, string) {
	r.Sync(marker)
	return r.pkg(), r.String()
}

// pkgScope returns pkg.Scope().
// If pkg is nil, it returns types.Universe instead.
//
// TODO(mdempsky): Remove after x/tools can depend on Go 1.19.
func pkgScope(pkg *types.Package) *types.Scope {
	if pkg != nil {
		return pkg.Scope()
	}
	return types.Universe
}