<a href="#Expressions">expression</a>; it is the most recent value
<a href="#Assignments">assigned</a> to the variable.
If a variable has not yet been assigned a value, its value is the
<a href="#The_zero_value">zero value</a> for its type.
</p>


<h2 id="Types">Types</h2>

<p>
A type determines a set of values together with operations and methods specific

	"os/exec"
	"runtime"
	"syscall"
	"testing"
	"time"
)

func test18146(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in short mode")
	}

	if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
		t.Skipf("skipping flaky test on %s; see golang.org/issue/18202", runtime.GOOS)
	}

	if runtime.GOARCH == "mips" || runtime.GOARCH == "mips64" {
		t.Skipf("skipping on %s", runtime.GOARCH)
	}

	attempts := 1000

func parse(name string, src []byte, flags parser.Mode) *ast.File {
	ast1, err := parser.ParseFile(fset, name, src, flags)
	if err != nil {
		if list, ok := err.(scanner.ErrorList); ok {
			// If err is a scanner.ErrorList, its String will print just
			// the first error and then (+n more errors).
			// Instead, turn it into a new Error that will return
			// details for all the errors.
			for _, e := range list {
				fmt.Fprintln(os.Stderr, e)

#cgo directives within these comments to tweak the behavior of the C, C++
or Fortran compiler. Values defined in multiple directives are concatenated
together. The directive can include a list of build constraints limiting its
effect to systems satisfying one of the constraints
(see https://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
For example:

	// #cgo CFLAGS: -DPNG_DEBUG=1

	const padding = 3 // Extra padding for ' ', '=', and '\n'
	size := len(k) + len(v) + padding
	size += len(strconv.Itoa(size))
	record := strconv.Itoa(size) + " " + k + "=" + v + "\n"

	// Final adjustment if adding size field increased the record size.
	if len(record) != size {
		size = len(record)
		record = strconv.Itoa(size) + " " + k + "=" + v + "\n"
	}
	return record, nil
}

		if dt.ByteSize < 0 && tag == "" { // opaque unnamed struct - should not be possible
			break
		}
		if tag == "" {
			tag = anonymousStructTag[dt]
			if tag == "" {
				tag = "__" + strconv.Itoa(tagGen)
				tagGen++
				anonymousStructTag[dt] = tag
			}
		} else if t.C.Empty() {
			t.C.Set(dt.Kind + " " + tag)
		}
		name := c.Ident("_Ctype_" + dt.Kind + "_" + tag)

	m, ok := b.tryGrowByReslice(1)
	if !ok {
		m = b.grow(1)
	}
	b.buf[m] = c
	return nil
}

// WriteRune appends the UTF-8 encoding of Unicode code point r to the
// buffer, returning its length and an error, which is always nil but is
// included to match [bufio.Writer]'s WriteRune. The buffer is grown as needed;
// if it becomes too large, WriteRune will panic with [ErrTooLarge].

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

//go:build ignore

// Mkzip writes a zoneinfo.zip with the content of the current directory
// and its subdirectories, with no compression, suitable for package time.
//
// Usage:
//
//	go run ../../mkzip.go ../../zoneinfo.zip
//
// We use this program instead of 'zip -0 -r ../../zoneinfo.zip *' to get

because it documents the full list of known GODEBUG settings,
which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.
If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:

  x.go:3		0x1050203		e83882ffff		CALL runtime.morestack_noctxt(SB)
  x.go:3		0x1050208		ebb6			JMP main.main(SB)
</pre>

<h3 id="constants">Constants</h3>

<p>
Although the assembler takes its guidance from the Plan 9 assemblers,
it is a distinct program, so there are some differences.
One is in constant evaluation.
Constant expressions in the assembler are parsed using Go's operator