return newType != nil, IncompatibleAssign
	}
	// Vu is typed

	// x's type V and T have identical underlying types
	// and at least one of V or T is not a named type
	// and neither V nor T is a type parameter.
	if Identical(Vu, Tu) && (!hasName(V) || !hasName(T)) && Vp == nil && Tp == nil {
		return true, 0
	}

	// T is an interface type, but not a type parameter, and V implements T.

	if l == nil {
		return nil
	}
	return l.tparams
}

// TypeList holds a list of types.
type TypeList struct{ types []Type }

// newTypeList returns a new TypeList with the types in list.
func newTypeList(list []Type) *TypeList {
	if len(list) == 0 {
		return nil
	}
	return &TypeList{list}
}

// Len returns the number of types in the list.
// It is safe to call on a nil receiver.

	// These lookups and updates use reasonable looking types in an attempt to
	// make them robust to internal type assertions, but could equally well use
	// arbitrary types.

	// Create some distinct origin types. nullaryP and nullaryQ have no
	// parameters and are identical (but have different type parameter names).
	// unaryP has a parameter.
	var nullaryP, nullaryQ, unaryP Type
	{
		// type nullaryP = func[P any]()

	// These lookups and updates use reasonable looking types in an attempt to
	// make them robust to internal type assertions, but could equally well use
	// arbitrary types.

	// Create some distinct origin types. nullaryP and nullaryQ have no
	// parameters and are identical (but have different type parameter names).
	// unaryP has a parameter.
	var nullaryP, nullaryQ, unaryP Type
	{
		// type nullaryP = func[P any]()

// This file tests built-in calls on generic types.

// derived and expanded from cmd/compile/internal/types2/testdata/check/builtins.go2

package builtins

// close

type C0 interface{ int }
type C1 interface{ chan int }
type C2 interface{ chan int | <-chan int }
type C3 interface{ chan int | chan float32 }
type C4 interface{ chan int | chan<- int }
type C5[T any] interface{ ~chan T | chan<- T }

			continue
		}

		CheckSize(m.Type)
		addMethod(m, true)
	}

	for _, m := range t.Methods() {
		if m.Sym != nil || m.Type == nil {
			continue
		}

		// In 1.18, embedded types can be anything. In Go 1.17, we disallow
		// embedding anything other than interfaces. This requirement was caught
		// by types2 already, so allow non-interface here.
		if !m.Type.IsInterface() {
			continue
		}

		}
		panic(msg)
	}
}

// An errorDesc describes part of a type-checking error.
type errorDesc struct {
	pos syntax.Pos
	msg string
}

// An error_ represents a type-checking error.
// A new error_ is created with Checker.newError.
// To report an error_, call error_.report.
type error_ struct {
	check *Checker
	desc  []errorDesc
	code  Code

// type of all types in its type set if it exists, or nil otherwise. If the
// type set contains only unrestricted and restricted channel types (with
// identical element types), the single underlying type is the restricted
// channel type if the restrictions are always the same, or nil otherwise.
func coreType(t Type) Type {
	t = Unalias(t)
	tpar, _ := t.(*TypeParam)
	if tpar == nil {
		return under(t)

		"{E}; type E interface{}":           "𝓤",
		"{E}; type E interface{int;string}": "∅",
		"{E}; type E interface{comparable}": "{comparable}",
	} {
		// parse
		errh := func(error) {} // dummy error handler so that parsing continues in presence of errors
		src := "package p; type T interface" + body
		file, err := syntax.Parse(nil, strings.NewReader(src), errh, nil, 0)

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package types2

import (
	"fmt"
)

// A Package describes a Go package.
type Package struct {
	path      string
	name      string
	scope     *Scope
	imports   []*Package
	complete  bool