" 5: *ast.Ident":      " the name is p\n",
	" 8: *ast.GenDecl":    "imports\n",
	" 9: *ast.ImportSpec": "bytes\n",
	"10: *ast.ImportSpec": "fmt\n",
	"16: *ast.GenDecl":    "T\nalso associated with T\n",
	"17: *ast.Field":      "associated with a, b, c\n",
	"19: *ast.Field":      "associated with x, y\nfloat values\n",
	"20: *ast.Field":      "complex value\n",
	"25: *ast.GenDecl":    "x\nx = 0\nalso associated with x\n",

	var groups [][]*ast.ImportSpec

	for _, decl := range f.Decls {
		genDecl, ok := decl.(*ast.GenDecl)
		if !ok || genDecl.Tok != token.IMPORT {
			break
		}

		group := []*ast.ImportSpec{}

		var lastLine int
		for _, spec := range genDecl.Specs {
			importSpec := spec.(*ast.ImportSpec)
			pos := importSpec.Path.ValuePos
			line := fset.Position(pos).Line

		pos := decl.Pos()
		relPosition := fset.Position(pos)
		absPosition := fset.PositionFor(pos, false)

		// Either a FuncDecl or GenDecl, since we exit on error.
		kind := "func"
		if gen, ok := decl.(*ast.GenDecl); ok {
			kind = gen.Tok.String()
		}

		// If the relative and absolute positions differ, show both.
		fmtPosition := relPosition.String()
		if relPosition != absPosition {

			Value: strconv.Quote(ipath),
		},
	}

	// Find an import decl to add to.
	var (
		bestMatch  = -1
		lastImport = -1
		impDecl    *ast.GenDecl
		impIndex   = -1
	)
	for i, decl := range f.Decls {
		gen, ok := decl.(*ast.GenDecl)
		if ok && gen.Tok == token.IMPORT {
			lastImport = i
			// Do not add to import "C", to avoid disrupting the
			// association with its doc comment, breaking cgo.

	for _, d := range depDecls {
		switch d := d.(type) {
		case *ast.GenDecl:
			if d.Doc != nil {
				comments = append(comments, d.Doc)
			}
		case *ast.FuncDecl:
			if d.Doc != nil {
				comments = append(comments, d.Doc)
			}
		}
	}

	// Synthesize import declaration.
	importDecl := &ast.GenDecl{
		Tok:    token.IMPORT,
		Lparen: 1, // Need non-zero Lparen and Rparen so that printer

	ast.Walk(s, f)
}

func removeEmptyDeclGroups(f *ast.File) {
	i := 0
	for _, d := range f.Decls {
		if g, ok := d.(*ast.GenDecl); !ok || !isEmpty(f, g) {
			f.Decls[i] = d
			i++
		}
	}
	f.Decls = f.Decls[:i]
}

func isEmpty(f *ast.File, g *ast.GenDecl) bool {
	if g.Doc != nil || g.Specs != nil {
		return false
	}

	for _, c := range f.Comments {

	wantLit := file.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Values[0].(*ast.BasicLit)
	wantVal := wantLit.Value

	var buf bytes.Buffer
	if err = Node(&buf, fset, file); err != nil {
		t.Fatal("Node failed:", err)
	}
	diff(t, buf.Bytes(), []byte(golden))

	// Check if anything changed after Node returned.
	gotLit := file.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Values[0].(*ast.BasicLit)

	case nil:
		return ""

	case *ast.GenDecl:
		// Formats const and var declarations.
		trailer := ""
		if len(n.Specs) > 1 {
			trailer = " " + dotDotDot
		}

		// Find the first relevant spec.
		typ := ""
		for i, spec := range n.Specs {
			valueSpec := spec.(*ast.ValueSpec) // Must succeed; we can't mix types in one GenDecl.

	fileNode = file
	fileSize = int64(len(src))

	for _, decl := range file.Decls {
		// The first global variable, which is pretty short:
		//
		//	var unresolved = new(ast.Object)
		if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.VAR {
			declNode = decl
			declSize = int64(fset.Position(decl.End()).Offset - fset.Position(decl.Pos()).Offset)
			break
		}

	}
}

func BenchmarkPrintFile(b *testing.B) {

	nodeFilter := []ast.Node{
		(*ast.AssignStmt)(nil),
		(*ast.CallExpr)(nil),
		(*ast.CompositeLit)(nil),
		(*ast.FuncDecl)(nil),
		(*ast.FuncLit)(nil),
		(*ast.GenDecl)(nil),
		(*ast.RangeStmt)(nil),
		(*ast.ReturnStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		switch node := node.(type) {
		case *ast.RangeStmt:
			checkCopyLocksRange(pass, node)