// infeasible, in which case the internal/godebugs table entry must set
// Opaque: true, and the documentation in doc/godebug.md should
// mention that metrics are unavailable.
//
// Conventionally, the global variable representing a godebug is named
// for the godebug itself, with no case changes:
//
//	var gotypesalias = godebug.New("gotypesalias") // this
//	var goTypesAlias = godebug.New("gotypesalias") // NOT THIS
//

The `godebug` lines in the previous example would be written:

	//go:debug default=go1.21
	//go:debug panicnil=1
	//go:debug asynctimerchan=0

Starting in Go 1.21, the Go toolchain treats a `//go:debug` directive
with an unrecognized GODEBUG setting as an invalid program.
Programs with more than one `//go:debug` line for a given setting
are also treated as invalid.
(Older toolchains ignore `//go:debug` directives entirely.)

			return "", "", fmt.Errorf("missing key=value")
		}
		return "", "", ErrNotGoDebug
	}
	k, v, ok := strings.Cut(strings.TrimSpace(text[i:]), "=")
	if !ok {
		return "", "", fmt.Errorf("missing key=value")
	}
	if err := modload.CheckGodebug("//go:debug setting", k, v); err != nil {
		return "", "", err
	}
	return k, v, nil
}

replace q => ./q
require rsc.io/panicnil v1.0.0

-- p.go --
//go:debug randautoseed=0

package main

func main() {
	panic(nil)
}

-- godebug.go --
//go:build godebug
//go:debug default=go1.20
//go:debug asynctimerchan=0

package main

-- godebugbad.go --
//go:build godebugbad
//go:debug default=go1.20 asynctimerchan=0

package main

-- q/go.mod --

use foo
use foo
-- go.work.badgodebug.txt --


godebug foo=1
-- go.work.unparsable.txt --




notadirective
-- go.work.firstlineerr.txt --
godebug bar=1
-- go.work.firsterrlisted.txt --
godebug baz=1

	line := f.Syntax.addLine(nil, "godebug", key+"="+value)
	g := &Godebug{
		Key:    key,
		Value:  value,
		Syntax: line,
	}
	f.Godebug = append(f.Godebug, g)
}

func (f *WorkFile) DropGodebug(key string) error {
	for _, g := range f.Godebug {
		if g.Key == key {
			g.Syntax.markRemoved()
			*g = Godebug{}
		}
	}
	return nil
}

func (f *WorkFile) AddUse(diskPath, modulePath string) error {

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

// Package godebugs provides a table of known GODEBUG settings,
// for use by a variety of other packages, including internal/godebug,
// runtime, runtime/metrics, and cmd/go/internal/load.
package godebugs

// An Info describes a single known GODEBUG setting.
type Info struct {
	Name    string // name of the setting ("panicnil")

			t.Errorf("Name=%s has Old, missing Changed", info.Name)
		}
		if !strings.Contains(doc, "`"+info.Name+"`") {
			t.Errorf("Name=%s not documented in doc/godebug.md", info.Name)
		}
		if !info.Opaque && !incs[info.Name] {
			t.Errorf("Name=%s missing IncNonDefault calls; see 'go doc internal/godebug'", info.Name)
		}
	}
}

var incNonDefaultRE = regexp.MustCompile(`([\pL\p{Nd}_]+)\.IncNonDefault\(\)`)

# Test case for #67623 in go.mod files: make sure the error for
# an unknown godebug is printed on a line starting with the file
# and line number, so it can be easily parsed by tools.

! go list
stderr '^go.mod:3: unknown godebug "foo"$'

-- go.mod --
module example.com/bar

	runDebugOptionsTest(t, "TestAllCapabilitiesDisabled", "cpu.all=off")
}

func TestAllCapabilitiesDisabled(t *testing.T) {
	MustHaveDebugOptionsSupport(t)

	if godebug.New("#cpu.all").Value() != "off" {
		t.Skipf("skipping test: GODEBUG=cpu.all=off not set")
	}

	for _, o := range Options {
		want := false
		if got := *o.Feature; got != want {
			t.Errorf("%v: expected %v, got %v", o.Name, want, got)
		}
	}