"io/fs"
	"log"
	"os"
	"path/filepath"
	"strings"
)

func usage() {
	fmt.Fprintf(os.Stderr, "usage: go run mkzip.go zoneinfo.zip\n")
	os.Exit(2)
}

func main() {
	log.SetPrefix("mkzip: ")
	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()
	args := flag.Args()
	if len(args) != 1 || !strings.HasSuffix(args[0], ".zip") {
		usage()
	}

	var zb bytes.Buffer
	zw := zip.NewWriter(&zb)

	(*m) = append(*m, val)
	return nil
}

func Usage() {
	fmt.Fprintf(os.Stderr, "usage: asm [options] file.s ...\n")
	fmt.Fprintf(os.Stderr, "Flags:\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func Parse() {
	objabi.Flagparse(Usage)
	if flag.NArg() == 0 {
		flag.Usage()
	}

	// Flag refinement.
	if *OutputFile == "" {
		if flag.NArg() != 1 {
			flag.Usage()
		}
		input := filepath.Base(flag.Arg(0))

func (tw *Writer) WriteHeader(hdr *Header) error {
	if err := tw.Flush(); err != nil {
		return err
	}
	tw.hdr = *hdr // Shallow copy of Header

	// Avoid usage of the legacy TypeRegA flag, and automatically promote
	// it to use TypeReg or TypeDir.
	if tw.hdr.Typeflag == TypeRegA {
		if strings.HasSuffix(tw.hdr.Name, "/") {
			tw.hdr.Typeflag = TypeDir
		} else {

		}
		tokens := Tokenize(name)
		if len(tokens) != 1 || tokens[0].ScanToken != scanner.Ident {
			fmt.Fprintf(os.Stderr, "asm: parsing -D: %q is not a valid identifier name\n", tokens[0])
			flags.Usage()
		}
		macros[name] = &Macro{
			name:   name,
			args:   nil,
			tokens: Tokenize(value),
		}
	}
	return macros
}

var panicOnError bool // For testing.

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

package main

import (
	"fmt"
	"os"
)

func main() {
	if len(os.Args) != 2 {
		fatal("usage: callback testname")
	}
	switch os.Args[1] {
	default:
		fatal("unknown test %q", os.Args[1])
	case "Call":
		testCall()
	case "Callback":
		testCallback()
	}
	println("OK")
}

	go tool fix -r egl <pkg>

The EGLConfig case was introduced in Go 1.15. Use the eglconf rewrite
to auto-update code from Go 1.14 and earlier:

	go tool fix -r eglconf <pkg>

# Using cgo directly

Usage:

	go tool cgo [cgo options] [-- compiler options] gofiles...

Cgo transforms the specified input Go source files into several output
Go and C source files.

	"os"
	"strings"

	"cmd/internal/buildid"
)

func usage() {
	fmt.Fprintf(os.Stderr, "usage: go tool buildid [-w] file\n")
	flag.PrintDefaults()
	os.Exit(2)
}

var wflag = flag.Bool("w", false, "write build ID")

func main() {
	log.SetPrefix("buildid: ")
	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()
	if flag.NArg() != 1 {
		usage()
	}

	file := flag.Arg(0)
	id, err := buildid.ReadFile(file)

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

/*
Buildid displays or updates the build ID stored in a Go package or binary.

Usage:

	go tool buildid [-w] file

By default, buildid prints the build ID found in the named file.
If the -w option is given, buildid rewrites the build ID found in
the file to accurately record a content hash of the file.

	lastRead readOp // last read operation, so that Unread* can work correctly.
}

// The readOp constants describe the last action performed on
// the buffer, so that UnreadRune and UnreadByte can check for
// invalid usage. opReadRuneX constants are chosen such that
// converted to int they correspond to the rune size that was read.
type readOp int8

// Don't use iota for these, as the values need to correspond with the

				//   BC 4,...
				// into
				//   BC $4,...
				prog.From = obj.Addr{
					Type:   obj.TYPE_CONST,
					Offset: p.getConstant(prog, op, &a[0]),
				}

			}

			// Likewise, fixup usage like:
			//   BC x,LT,...
			//   BC x,foo+2,...
			//   BC x,4
			//   BC x,$5
			// into
			//   BC x,CR0LT,...
			//   BC x,CR0EQ,...
			//   BC x,CR1LT,...
			//   BC x,CR1GT,...