}

func importPath(s Spec) string {
	t, err := strconv.Unquote(s.(*ImportSpec).Path.Value)
	if err == nil {
		return t
	}
	return ""
}

func importName(s Spec) string {
	n := s.(*ImportSpec).Name
	if n == nil {
		return ""
	}
	return n.Name
}

func importComment(s Spec) string {
	c := s.(*ImportSpec).Comment
	if c == nil {
		return ""
	}
	return c.Text()
}

func findImportGroupStarts(imps []*ast.ImportSpec) []token.Pos {
	startImps := findImportGroupStarts1(imps)
	groupStarts := make([]token.Pos, len(startImps))
	for i, imp := range startImps {
		groupStarts[i] = imp.Pos()
	}
	return groupStarts
}

// Helper for findImportGroupStarts to ease testing.
func findImportGroupStarts1(origImps []*ast.ImportSpec) []*ast.ImportSpec {
	// Copy to avoid mutation.

// constant, type, or variable declaration.
type (
	// The Spec type stands for any of *ImportSpec, *ValueSpec, and *TypeSpec.
	Spec interface {
		Node
		specNode()
	}

	// An ImportSpec node represents a single package import.
	ImportSpec struct {
		Doc     *CommentGroup // associated documentation; or nil
		Name    *Ident        // local package name (including "."); or nil

pkg go/types, method (*Alias) String() string #63223
pkg go/types, method (*Alias) Underlying() Type #63223
pkg go/types, method (*Info) PkgNameOf(*ast.ImportSpec) *PkgName #62037
pkg go/types, method (Checker) PkgNameOf(*ast.ImportSpec) *PkgName #62037
pkg go/types, type Alias struct #63223
pkg go/types, type Info struct, FileVersions map[*ast.File]string #62605
pkg go/version, func Compare(string, string) int #62039

	case *ast.Ident:
		children = append(children,
			tok(n.NamePos, len(n.Name)))

	case *ast.IfStmt:
		children = append(children,
			tok(n.If, len("if")))

	case *ast.ImportSpec:
		// TODO(adonovan): ImportSpec.{Doc,EndPos}?

	case *ast.IncDecStmt:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.IndexExpr:
		children = append(children,

func renameImportPath(f *ast.File, renames ...string) {
	m := makeRenameMap(renames...)
	ast.Inspect(f, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.ImportSpec:
			if n.Path.Kind != token.STRING {
				panic("invalid import path")
			}
			m.rename(&n.Path.Value)
			return false
		}
		return true
	})
}

func (obj *Object) Pos() token.Pos {
	name := obj.Name
	switch d := obj.Decl.(type) {
	case *Field:
		for _, n := range d.Names {
			if n.Name == name {
				return n.Pos()
			}
		}
	case *ImportSpec:
		if d.Name != nil && d.Name.Name == name {
			return d.Name.Pos()
		}
		return d.Path.Pos()
	case *ValueSpec:
		for _, n := range d.Names {
			if n.Name == name {
				return n.Pos()
			}
		}

		return 1 << nFuncType
	case *ast.GenDecl:
		return 1 << nGenDecl
	case *ast.GoStmt:
		return 1 << nGoStmt
	case *ast.Ident:
		return 1 << nIdent
	case *ast.IfStmt:
		return 1 << nIfStmt
	case *ast.ImportSpec:
		return 1 << nImportSpec
	case *ast.IncDecStmt:
		return 1 << nIncDecStmt
	case *ast.IndexExpr:
		return 1 << nIndexExpr
	case *ast.IndexListExpr:
		return 1 << nIndexListExpr
	case *ast.InterfaceType:

		}

		// Add special dot-import declaration:
		//    import . "·this·"
		var decls []ast.Decl
		decls = append(decls, &ast.GenDecl{
			Tok: token.IMPORT,
			Specs: []ast.Spec{
				&ast.ImportSpec{
					Name: &ast.Ident{Name: "."},
					Path: &ast.BasicLit{
						Kind:  token.STRING,
						Value: strconv.Quote(thispkg),
					},
				},
			},
		})

	// Implicits maps nodes to their implicitly declared objects, if any.
	// The following node and object types may appear:
	//
	//     node               declared object
	//
	//     *ast.ImportSpec    *PkgName for imports without renames
	//     *ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
	//     *ast.Field         anonymous parameter *Var (incl. unnamed results)
	//