Tan3pio8 = 2.41421356237309504880      // tan(3*pi/8)
	)
	if x <= 0.66 {
		return xatan(x)
	}
	if x > Tan3pio8 {
		return Pi/2 - xatan(1/x) + Morebits
	}
	return Pi/4 + xatan((x-1)/(x+1)) + 0.5*Morebits
}

// Atan returns the arctangent, in radians, of x.
//
// Special cases are:
//
//	Atan(±0) = ±0
//	Atan(±Inf) = ±Pi/2
func Atan(x float64) float64 {
	if haveArchAtan {
		return archAtan(x)

func NewChan(dir ChanDir, elem Type) *Chan {
	return &Chan{dir: dir, elem: elem}
}

// Dir returns the direction of channel c.
func (c *Chan) Dir() ChanDir { return c.dir }

// Elem returns the element type of channel c.
func (c *Chan) Elem() Type { return c.elem }

func (c *Chan) Underlying() Type { return c }

	// instead of idx itself.  However, in a future version of this function,
	// we can use idx to better handle the case of elemsize==0.
	// A future improvement to the detector is to call TSan with c and idx:
	// this way, Go will continue to not allocating buffer entries for channels
	// of elemsize==0, yet the race detector can be made to handle multiple
	// sync objects underneath the hood (one sync object per idx)

	-5.38695755929454629881e7, // 0xc189afe03cbe5a31
}

// Tan returns the tangent of the radian argument x.
//
// Special cases are:
//
//	Tan(±0) = ±0
//	Tan(±Inf) = NaN
//	Tan(NaN) = NaN
func Tan(x float64) float64 {
	if haveArchTan {
		return archTan(x)
	}
	return tan(x)
}

func tan(x float64) float64 {
	const (

func TestRaceForTest(t *testing.T) {
	done := make(chan bool)
	c := make(chan bool)
	stop := false
	go func() {
		for {
			_, ok := <-c
			if !ok {
				done <- true
				return
			}
			stop = true
		}
	}()
	for !stop {
		c <- true
	}
	close(c)
	<-done
}

func TestRaceForIncr(t *testing.T) {
	done := make(chan bool)
	c := make(chan bool)
	x := 0
	go func() {
		for {

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

type Chan[T any] chan Chan[T]

func (ch Chan[T]) recv() Chan[T] {
	return <-ch
}

func main() {
	ch := Chan[int](make(chan Chan[int]))
	go func() {
		ch <- make(Chan[int])
	}()
	ch.recv()

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package p

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 }

func _[T any](ch T) {

func ch1[P chan<- int]() (_ P)           { return } // core(P) == chan<- int   (single type, no tilde)
func ch2[P ~chan int]()                  { return } // core(P) == ~chan<- int  (tilde)
func ch3[P chan E, E any](E)             { return } // core(P) == chan<- E     (single type, no tilde)
func ch4[P chan E | ~chan<- E, E any](E) { return } // core(P) == ~chan<- E    (tilde)

	// maps
	dup("map[string]int"),
	{"map[struct{x, y int}][]byte", "map[struct{x int; y int}][]byte"},

	// channels
	dup("chan<- chan int"),
	dup("chan<- <-chan int"),
	dup("<-chan <-chan int"),
	dup("chan (<-chan int)"),
	dup("chan<- func()"),
	dup("<-chan []func() int"),
}

// types that depend on other type declarations (src in TestTypes)
var dependentTestTypes = []testEntry{
	// interfaces

	components chan task
	done       chan struct{}

	// requiredTerminations keeps track of tasks that should block instance exit
	// if they are not stopped. This allows important cleanup tasks to be completed.
	// Note: this is still best effort; a process can die at any time.
	requiredTerminations sync.WaitGroup
}

func (i *instance) Start(stop <-chan struct{}) error {
	shutdown := func() {
		close(i.done)
	}