// Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
// Source: ../../cmd/compile/internal/types2/alias.go

// Copyright 2023 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 types

import (
	
	
)

// An Alias represents an alias type.
//
// Alias types are created by alias declarations such as:
//
//	type A = int
//
// The type on the right-hand side of the declaration can be accessed
// using [Alias.Rhs]. This type may itself be an alias.
// Call [Unalias] to obtain the first non-alias type in a chain of
// alias type declarations.
//
// Like a defined ([Named]) type, an alias type has a name.
// Use the [Alias.Obj] method to access its [TypeName] object.
//
// Historically, Alias types were not materialized so that, in the example
// above, A's type was represented by a Basic (int), not an Alias
// whose [Alias.Rhs] is int. But Go 1.24 allows you to declare an
// alias type with type parameters or arguments:
//
//	type Set[K comparable] = map[K]bool
//	s := make(Set[String])
//
// and this requires that Alias types be materialized. Use the
// [Alias.TypeParams] and [Alias.TypeArgs] methods to access them.
//
// To ease the transition, the Alias type was introduced in go1.22,
// but the type-checker would not construct values of this type unless
// the GODEBUG=gotypesalias=1 environment variable was provided.
// Starting in go1.23, this variable is enabled by default.
// This setting also causes the predeclared type "any" to be
// represented as an Alias, not a bare [Interface].
type Alias struct {
	obj     *TypeName      // corresponding declared alias object
	orig    *Alias         // original, uninstantiated alias
	tparams *TypeParamList // type parameters, or nil
	targs   *TypeList      // type arguments, or nil
	fromRHS Type           // RHS of type alias declaration; may be an alias
	actual  Type           // actual (aliased) type; never an alias
}

// NewAlias creates a new Alias type with the given type name and rhs.
// rhs must not be nil.
func ( *TypeName,  Type) *Alias {
	 := (*Checker)(nil).newAlias(, )
	// Ensure that alias.actual is set (#65455).
	.cleanup()
	return 
}

// Obj returns the type name for the declaration defining the alias type a.
// For instantiated types, this is same as the type name of the origin type.
func ( *Alias) () *TypeName { return .orig.obj }

func ( *Alias) () string { return TypeString(, nil) }

// Underlying returns the [underlying type] of the alias type a, which is the
// underlying type of the aliased type. Underlying types are never Named,
// TypeParam, or Alias types.
//
// [underlying type]: https://go.dev/ref/spec#Underlying_types.
func ( *Alias) () Type { return unalias().Underlying() }

// Origin returns the generic Alias type of which a is an instance.
// If a is not an instance of a generic alias, Origin returns a.
func ( *Alias) () *Alias { return .orig }

// TypeParams returns the type parameters of the alias type a, or nil.
// A generic Alias and its instances have the same type parameters.
func ( *Alias) () *TypeParamList { return .tparams }

// SetTypeParams sets the type parameters of the alias type a.
// The alias a must not have type arguments.
func ( *Alias) ( []*TypeParam) {
	assert(.targs == nil)
	.tparams = bindTParams()
}

// TypeArgs returns the type arguments used to instantiate the Alias type.
// If a is not an instance of a generic alias, the result is nil.
func ( *Alias) () *TypeList { return .targs }

// Rhs returns the type R on the right-hand side of an alias
// declaration "type A = R", which may be another alias.
func ( *Alias) () Type { return .fromRHS }

// Unalias returns t if it is not an alias type;
// otherwise it follows t's alias chain until it
// reaches a non-alias type which is then returned.
// Consequently, the result is never an alias type.
func ( Type) Type {
	if ,  := .(*Alias);  != nil {
		return unalias()
	}
	return 
}

func unalias( *Alias) Type {
	if .actual != nil {
		return .actual
	}
	var  Type
	for  := ;  != nil; , _ = .(*Alias) {
		 = .fromRHS
	}
	if  == nil {
		panic(fmt.Sprintf("non-terminated alias %s", .obj.name))
	}

	// Memoize the type only if valid.
	// In the presence of unfinished cyclic declarations, Unalias
	// would otherwise latch the invalid value (#66704).
	// TODO(adonovan): rethink, along with checker.typeDecl's use
	// of Invalid to mark unfinished aliases.
	if  != Typ[Invalid] {
		.actual = 
	}

	return 
}

// asNamed returns t as *Named if that is t's
// actual type. It returns nil otherwise.
func asNamed( Type) *Named {
	,  := Unalias().(*Named)
	return 
}

// newAlias creates a new Alias type with the given type name and rhs.
// rhs must not be nil.
func ( *Checker) ( *TypeName,  Type) *Alias {
	assert( != nil)
	 := new(Alias)
	.obj = 
	.orig = 
	.fromRHS = 
	if .typ == nil {
		.typ = 
	}

	// Ensure that a.actual is set at the end of type checking.
	if  != nil {
		.needsCleanup()
	}

	return 
}

// newAliasInstance creates a new alias instance for the given origin and type
// arguments, recording pos as the position of its synthetic object (for error
// reporting).
func ( *Checker) ( token.Pos,  *Alias,  []Type,  *Named,  *Context) *Alias {
	assert(len() > 0)
	 := NewTypeName(, .obj.pkg, .obj.name, nil)
	 := .subst(, .fromRHS, makeSubstMap(.TypeParams().list(), ), , )
	 := .newAlias(, )
	.orig = 
	.tparams = .tparams
	.targs = newTypeList()
	return 
}

func ( *Alias) () {
	// Ensure a.actual is set before types are published,
	// so Unalias is a pure "getter", not a "setter".
	 := Unalias()

	if  == Typ[Invalid] {
		// We don't set a.actual to Typ[Invalid] during type checking,
		// as it may indicate that the RHS is not fully set up.
		.actual = 
	}
}