_Recover

	// package unsafe
	_Add
	_Alignof
	_Offsetof
	_Sizeof
	_Slice
	_SliceData
	_String
	_StringData

	// testing support
	_Assert
	_Trace
)

var predeclaredFuncs = [...]struct {
	name     string
	nargs    int
	variadic bool
	kind     exprKind
}{
	_Append:  {"append", 1, true, expression},
	_Cap:     {"cap", 1, false, expression},

	_Recover

	// package unsafe
	_Add
	_Alignof
	_Offsetof
	_Sizeof
	_Slice
	_SliceData
	_String
	_StringData

	// testing support
	_Assert
	_Trace
)

var predeclaredFuncs = [...]struct {
	name     string
	nargs    int
	variadic bool
	kind     exprKind
}{
	_Append:  {"append", 1, true, expression},
	_Cap:     {"cap", 1, false, expression},

func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ bool) {
	argList := call.Args

	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if hasDots(call) && id != _Append {
		check.errorf(dddErrPos(call),
			InvalidDotDotDot,
			invalidOp+"invalid use of ... with built-in %s", bin.name)
		check.use(argList...)
		return
	}

func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (_ bool) {
	argList := call.ArgList

	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if hasDots(call) && id != _Append {
		check.errorf(dddErrPos(call),
			InvalidDotDotDot,
			invalidOp+"invalid use of ... with built-in %s", bin.name)
		check.use(argList...)
		return
	}

			return "nil"
		}
	}

	var buf bytes.Buffer

	var expr string
	if x.expr != nil {
		expr = ExprString(x.expr)
	} else {
		switch x.mode {
		case builtin:
			expr = predeclaredFuncs[x.id].name
		case typexpr:
			expr = TypeString(x.typ, qf)
		case constant_:
			expr = x.val.String()
		}
	}

	// <expr> (
	if expr != "" {
		buf.WriteString(expr)

			return "nil"
		}
	}

	var buf bytes.Buffer

	var expr string
	if x.expr != nil {
		expr = ExprString(x.expr)
	} else {
		switch x.mode {
		case builtin:
			expr = predeclaredFuncs[x.id].name
		case typexpr:
			expr = TypeString(x.typ, qf)
		case constant_:
			expr = x.val.String()
		}
	}

	// <expr> (
	if expr != "" {
		buf.WriteString(expr)

// Predeclared identifiers

// IsPredeclared reports whether s is a predeclared identifier.
func IsPredeclared(s string) bool {
	return predeclaredTypes[s] || predeclaredFuncs[s] || predeclaredConstants[s]
}

var predeclaredTypes = map[string]bool{
	"any":        true,
	"bool":       true,
	"byte":       true,
	"comparable": true,
	"complex64":  true,

// A Builtin represents a built-in function.
// Builtins don't have a valid type.
type Builtin struct {
	object
	id builtinId
}

func newBuiltin(id builtinId) *Builtin {
	return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid], color_: black}, id}
}

// Nil represents the predeclared value nil.
type Nil struct {
	object
}

func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {

	depDecls, unresolved := findDeclsAndUnresolved(body, topDecls, typMethods)

	// Remove predeclared identifiers from unresolved list.
	for n := range unresolved {
		if predeclaredTypes[n] || predeclaredConstants[n] || predeclaredFuncs[n] {
			delete(unresolved, n)
		}
	}

	// Use unresolved identifiers to determine the imports used by this
	// example. The heuristic assumes package names match base import

// A Builtin represents a built-in function.
// Builtins don't have a valid type.
type Builtin struct {
	object
	id builtinId
}

func newBuiltin(id builtinId) *Builtin {
	return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid], color_: black}, id}
}

// Nil represents the predeclared value nil.
type Nil struct {
	object
}

func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {