// The Scopes mapping does not contain an entry for the
	// function body ([*ast.BlockStmt]); the function's scope is
	// associated with the [*ast.FuncType].
	//
	// The following node types may appear in Scopes:
	//
	//     *ast.File
	//     *ast.FuncType
	//     *ast.TypeSpec
	//     *ast.BlockStmt
	//     *ast.IfStmt
	//     *ast.SwitchStmt
	//     *ast.TypeSwitchStmt
	//     *ast.CaseClause

	// The Scopes mapping does not contain an entry for the
	// function body ([*ast.BlockStmt]); the function's scope is
	// associated with the [*ast.FuncType].
	//
	// The following node types may appear in Scopes:
	//
	//     *syntax.File
	//     *syntax.FuncType
	//     *syntax.TypeDecl
	//     *syntax.BlockStmt
	//     *syntax.IfStmt
	//     *syntax.SwitchStmt
	//     *syntax.CaseClause

		Walk(v, n.Key)
		Walk(v, n.Value)

	// Types
	case *ArrayType:
		if n.Len != nil {
			Walk(v, n.Len)
		}
		Walk(v, n.Elt)

	case *StructType:
		Walk(v, n.Fields)

	case *FuncType:
		if n.TypeParams != nil {
			Walk(v, n.TypeParams)
		}
		if n.Params != nil {
			Walk(v, n.Params)
		}
		if n.Results != nil {
			Walk(v, n.Results)
		}

	case *InterfaceType:

			if t != nil {
				w.node(t)
			}
		}

	case *Field:
		if n.Name != nil {
			w.node(n.Name)
		}
		w.node(n.Type)

	case *InterfaceType:
		w.fieldList(n.MethodList)

	case *FuncType:
		w.fieldList(n.ParamList)
		w.fieldList(n.ResultList)

	case *MapType:
		w.node(n.Key)
		w.node(n.Value)

	case *ChanType:
		w.node(n.Elem)

	// statements

				p.printFieldList(n.FieldList, n.TagList, _Semi)
				p.print(outdent, newline)
			} else {
				p.printFieldList(n.FieldList, n.TagList, _Semi)
			}
		}
		p.print(_Rbrace)

	case *FuncType:
		p.print(_Func)
		p.printSignature(n)

	case *InterfaceType:
		p.print(_Interface)
		if p.linebreaks && len(n.MethodList) > 1 {
			p.print(blank)
			p.print(_Lbrace)
			p.print(newline, indent)

			if !isValid(typ.base) {
				return Typ[Invalid]
			}
			return typ
		}

		check.errorf(e0, NotAType, "%s is not a type", e0)
		check.use(e0)

	case *syntax.FuncType:
		typ := new(Signature)
		setDefType(def, typ)
		check.funcType(typ, nil, nil, e)
		return typ

	case *syntax.InterfaceType:
		typ := check.newInterface()
		setDefType(def, typ)
		check.interfaceType(typ, e, def)
		return typ

		typ.base = Typ[Invalid] // avoid nil base in invalid recursive type declaration
		setDefType(def, typ)
		typ.base = check.varType(e.X)
		return typ

	case *ast.FuncType:
		typ := new(Signature)
		setDefType(def, typ)
		check.funcType(typ, nil, e)
		return typ

	case *ast.InterfaceType:
		typ := check.newInterface()
		setDefType(def, typ)
		check.interfaceType(typ, e, def)
		return typ

			r.filterType(nil, t.Y)
		}
	case *ast.ArrayType:
		r.filterType(nil, t.Elt)
	case *ast.StructType:
		if r.filterFieldList(parent, t.Fields, nil) {
			t.Incomplete = true
		}
	case *ast.FuncType:
		r.filterParamList(t.TypeParams)
		r.filterParamList(t.Params)
		r.filterParamList(t.Results)
	case *ast.InterfaceType:
		if r.filterFieldList(parent, t.Methods, t) {
			t.Incomplete = true
		}

	results = p.parseResult(scope)

	return
}

func (p *parser) parseFuncType() (*ast.FuncType, *ast.Scope) {
	if p.trace {
		defer un(trace(p, "FuncType"))
	}

	pos := p.expect(token.FUNC)
	scope := ast.NewScope(p.topScope) // function scope
	params, results := p.parseSignature(scope)

	return &ast.FuncType{pos, params, results}, scope
}

func (p *parser) parseMethodSpec(scope *ast.Scope) *ast.Field {

	return nil
}

func (p *parser) parseFuncType() *ast.FuncType {
	if p.trace {
		defer un(trace(p, "FuncType"))
	}

	pos := p.expect(token.FUNC)
	tparams, params := p.parseParameters(true)
	if tparams != nil {
		p.error(tparams.Pos(), "function type must have no type parameters")
	}
	results := p.parseResult()

	return &ast.FuncType{Func: pos, Params: params, Results: results}
}