These new behaviors are only enabled when the main Go program
is in a module with a `go.mod` `go` line using Go 1.23.0 or later.
When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
can be used to revert back to asynchronous channel behaviors

// license that can be found in the LICENSE file.

package tls

import (
	"internal/godebug"
	"slices"
	_ "unsafe" // for linkname
)

// Defaults are collected in this file to allow distributions to more easily patch
// them to apply local policies.

var tlskyber = godebug.New("tlskyber")

func defaultCurvePreferences() []CurveID {
	if tlskyber.Value() == "0" {

//
// This function is expensive! Call it sparingly.
func Enabled() bool {
	// The only reliable way to compute the answer is to invoke go/types.
	// We don't parse the GODEBUG environment variable, because
	// (a) it's tricky to do so in a manner that is consistent
	//     with the godebug package; in particular, a simple
	//     substring check is not good enough. The value is a
	//     rightmost-wins list of options. But more importantly:

var godebugNewIncNonDefault atomic.Pointer[func(string) func()]

//go:linkname godebug_setUpdate internal/godebug.setUpdate
func godebug_setUpdate(update func(string, string)) {
	p := new(func(string, string))
	*p = update
	godebugUpdate.Store(p)
	godebugNotify(false)
}

//go:linkname godebug_setNewIncNonDefault internal/godebug.setNewIncNonDefault
func godebug_setNewIncNonDefault(newIncNonDefault func(string) func()) {

<!-- CL 577715, CL 579076 -->
By default, go/types now produces [Alias] type nodes for type aliases.
This behavior can be controlled by the `GODEBUG` `gotypesalias` flag.

				continue field
			}
		}

		print("GODEBUG sys/cpu: unknown cpu feature \"", key, "\"\n")
	}

	for _, o := range options {
		if !o.Specified {
			continue
		}

		if o.Enable && !*o.Feature {
			print("GODEBUG sys/cpu: can not enable \"", o.Name, "\", missing CPU support\n")
			continue
		}

		if !o.Enable && o.Required {

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

package aliasTypes

type _ = int

// the pre-Go 1.22 ServeMux implementation for backwards compatibility.
// Do not modify this file, it should remain frozen.

import (
	"internal/godebug"
	"net/url"
	"sort"
	"strings"
	"sync"
)

var httpmuxgo121 = godebug.New("httpmuxgo121")

var use121 bool

// Read httpmuxgo121 once at startup, since dealing with changes to it during
// program execution is too complex and error-prone.

  traceSampling: 1.0
  image: pilot
  env:
    GODEBUG: gctrace=1
global:
  hub: docker.io/istio
  istioNamespace: istio-system
  tag: 1.2.3
  proxy:
    readinessInitialDelaySeconds: 2
`,
			want: `
hub: docker.io/istio
tag: 1.2.3
components:
   pilot:
     enabled: true
     k8s:
       replicaCount: 1
       env:
       - name: GODEBUG
         value: gctrace=1
       nodeSelector:

cmp stdout go.work.want_print

go work edit -json -go 1.19 -use b -dropuse c -replace 'x.1@v1.4.0 = ../z' -dropreplace x.1 -dropreplace x.1@v1.3.0
cmp stdout go.work.want_json

# go work edit -godebug
cd $WORK/g
cp go.work.start go.work
go work edit -godebug key=value
cmpenv go.work go.work.edit
go work edit -dropgodebug key2
cmpenv go.work go.work.edit
go work edit -dropgodebug key
cmpenv go.work go.work.start