return n
}

type (
	Expr interface {
		Node
		typeInfo
		aExpr()
	}

	// Placeholder for an expression that failed to parse
	// correctly and where we can't provide a better node.
	BadExpr struct {
		expr
	}

	// Value
	Name struct {
		Value string
		expr
	}

	// Value
	BasicLit struct {
		Value string
		Kind  LitKind

			f.walk(&n.Type, ctxEmbedType, visit)
		} else {
			f.walk(&n.Type, ctxType, visit)
		}
	case *ast.FieldList:
		for _, field := range n.List {
			f.walk(field, context, visit)
		}
	case *ast.BadExpr:
	case *ast.Ident:
	case *ast.Ellipsis:
		f.walk(&n.Elt, ctxType, visit)
	case *ast.BasicLit:
	case *ast.FuncLit:
		f.walk(n.Type, ctxType, visit)
		f.walk(n.Body, ctxStmt, visit)
	case *ast.CompositeLit:

		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Tag", nil, n.Tag)
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.FieldList:
		a.applyList(n, "List")

	// Expressions
	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
		// nothing to do

	case *ast.Ellipsis:
		a.apply(n, "Elt", nil, n.Elt)

	case *ast.FuncLit:
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Body", nil, n.Body)

		walkBeforeAfter(&n.Type, before, after)
		walkBeforeAfter(&n.Tag, before, after)
	case *ast.FieldList:
		for _, field := range n.List {
			walkBeforeAfter(field, before, after)
		}
	case *ast.BadExpr:
	case *ast.Ident:
	case *ast.Ellipsis:
		walkBeforeAfter(&n.Elt, before, after)
	case *ast.BasicLit:
	case *ast.FuncLit:
		walkBeforeAfter(&n.Type, before, after)
		walkBeforeAfter(&n.Body, before, after)

				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
			} else {
				check.trace(e0.Pos(), "=> %s (under = %s) // %s", T, under, goTypeName(T))
			}
		}()
	}

	switch e := e0.(type) {
	case *syntax.BadExpr:
		// ignore - error reported before

	case *syntax.Name:
		var x operand
		check.ident(&x, e, def, true)

		switch x.mode {
		case typexpr:
			typ := x.typ
			setDefType(def, typ)

				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
			} else {
				check.trace(e0.Pos(), "=> %s (under = %s) // %s", T, under, goTypeName(T))
			}
		}()
	}

	switch e := e0.(type) {
	case *ast.BadExpr:
		// ignore - error reported before

	case *ast.Ident:
		var x operand
		check.ident(&x, e, def, true)

		switch x.mode {
		case typexpr:
			typ := x.typ
			setDefType(def, typ)

	// 	//p.print(newline)
	// }
}

func (p *printer) printRawNode(n Node) {
	switch n := n.(type) {
	case nil:
		// we should not reach here but don't crash

	// expressions and types
	case *BadExpr:
		p.print(_Name, "<bad expr>")

	case *Name:
		p.print(_Name, n.Value) // _Name requires actual value following immediately

	case *BasicLit:

	old, found := check.untyped[x]
	if !found {
		return // nothing to do
	}

	// update operands of x if necessary
	switch x := x.(type) {
	case *ast.BadExpr,
		*ast.FuncLit,
		*ast.CompositeLit,
		*ast.IndexExpr,
		*ast.SliceExpr,
		*ast.TypeAssertExpr,
		*ast.StarExpr,
		*ast.KeyValueExpr,
		*ast.ArrayType,
		*ast.StructType,
		*ast.FuncType,

		t.Errorf("for File.FileEnd, got %s, want %s", got, want)
	}
}

// TestIncompleteSelection ensures that an incomplete selector
// expression is parsed as a (blank) *ast.SelectorExpr, not a
// *ast.BadExpr.
func TestIncompleteSelection(t *testing.T) {
	for _, src := range []string{
		"package p; var _ = fmt.",             // at EOF
		"package p; var _ = fmt.\ntype X int", // not at EOF
	} {

		rtyp = ptyp.X
		if unpackParams {
			for _, arg := range syntax.UnpackListExpr(ptyp.Index) {
				var par *syntax.Name
				switch arg := arg.(type) {
				case *syntax.Name:
					par = arg
				case *syntax.BadExpr:
					// ignore - error already reported by parser
				case nil:
					check.error(ptyp, InvalidSyntaxTree, "parameterized receiver contains nil parameters")
				default: