</pre>

<p>
Productions are expressions constructed from terms and the following
operators, in increasing precedence:
</p>
<pre class="grammar">
|   alternation
()  grouping
[]  option (0 or 1 times)
{}  repetition (0 to n times)
</pre>

<p>
Lower-case production names are used to identify lexical tokens.
Non-terminals are in CamelCase. Lexical tokens are enclosed in
double quotes <code>""</code> or back quotes <code>``</code>.

	TypeXHeader = 'x'

	// Type 'g' is used by the PAX format to store key-value records that
	// are relevant to all subsequent files.
	// This package only supports parsing and composing such headers,
	// but does not currently support persisting the global state across files.
	TypeXGlobalHeader = 'g'

	// Type 'S' indicates a sparse file in the GNU format.
	TypeGNUSparse = 'S'

---
title: "Go, Backwards Compatibility, and GODEBUG"
layout: article
---

<!--
This document is kept in the Go repo, not x/website,
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.

		}
		seen[name] = true
		return nil
	})
	if err != nil {
		log.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		log.Fatal(err)
	}
	if len(seen) == 0 {
		log.Fatalf("did not find any files to add")
	}
	if !seen["US/Eastern"] {
		log.Fatalf("did not find US/Eastern to add")
	}
	if err := os.WriteFile(args[0], zb.Bytes(), 0666); err != nil {
		log.Fatal(err)
	}

}

func ExampleSplitAfterN() {
	fmt.Printf("%q\n", bytes.SplitAfterN([]byte("a,b,c"), []byte(","), 2))
	// Output: ["a," "b,c"]
}

func ExampleTitle() {
	fmt.Printf("%s", bytes.Title([]byte("her royal highness")))
	// Output: Her Royal Highness
}

func ExampleToTitle() {
	fmt.Printf("%s\n", bytes.ToTitle([]byte("loud noises")))
	fmt.Printf("%s\n", bytes.ToTitle([]byte("хлеб")))
	// Output:

	return unicode.IsSpace(r)
}

// Title treats s as UTF-8-encoded bytes and returns a copy with all Unicode letters that begin
// words mapped to their title case.
//
// Deprecated: The rule Title uses for word boundaries does not handle Unicode
// punctuation properly. Use golang.org/x/text/cases instead.
func Title(s []byte) []byte {
	// Use a closure here to remember state.

</p>

<p>
The declaration order of variables declared in multiple files is determined
by the order in which the files are presented to the compiler: Variables
declared in the first file are declared before any of the variables declared
in the second file, and so on.
To ensure reproducible initialization behavior, build systems are encouraged
to present multiple files belonging to the same package in lexical file name
order to a compiler.

The [Stat] function now sets the [ModeSocket] bit for
files that are Unix sockets on Windows. These files are identified

	filenames := append(append([]string{}, info.GoFiles...), info.CgoFiles...)

	// Parse package files.
	var files []*ast.File
	for _, file := range filenames {
		f, err := w.parseFile(dir, file)
		if err != nil {
			log.Fatalf("error parsing package %s: %s", name, err)
		}
		files = append(files, f)
	}

	// Type-check package files.
	var sizes types.Sizes
	if w.context != nil {

	// Externally, Next iterates through the tar archive as if it is a series of
	// files. Internally, the tar format often uses fake "files" to add meta
	// data that describes the next file. These meta data "files" should not
	// normally be visible to the outside. As such, this loop iterates through
	// one or more "header files" until it finds a "normal file".
	format := FormatUSTAR | FormatPAX | FormatGNU
	for {