means that if a header file foo/bar.h exists both in the source
directory and also in the system include directory (or some other place
specified by a -I flag), then "#include <foo/bar.h>" will always find the
local version in preference to any other version.

The cgo tool is enabled by default for native builds on systems where
it is expected to work. It is disabled by default when cross-compiling

	"strings"
	"time"
)

// BUG: Use of the Uid and Gid fields in Header could overflow on 32-bit
// architectures. If a large value is encountered when decoding, the result
// stored in Header will be the truncated version.

var tarinsecurepath = godebug.New("tarinsecurepath")

var (
	ErrHeader          = errors.New("archive/tar: invalid tar header")
	ErrWriteTooLong    = errors.New("archive/tar: write too long")

its value is derived from three sources:
the defaults for the Go toolchain used to build the program,
amended to match the Go version listed in `go.mod`,
and then overridden by explicit `//go:debug` lines in the program.

The [GODEBUG History](#history) gives the exact defaults for each Go toolchain version.
For example, Go 1.21 introduces the `panicnil` setting,
controlling whether `panic(nil)` is allowed;

	// Identify the version of GNU headers.
	var is1x0 bool
	major, minor := hdr.PAXRecords[paxGNUSparseMajor], hdr.PAXRecords[paxGNUSparseMinor]
	switch {
	case major == "0" && (minor == "0" || minor == "1"):
		is1x0 = false
	case major == "1" && minor == "0":
		is1x0 = true
	case major != "" || minor != "":
		return nil, nil // Unknown GNU sparse PAX version
	case hdr.PAXRecords[paxGNUSparseMap] != "":

		b.uint32(directory64EndSignature)
		b.uint64(directory64EndLen - 12) // length minus signature (uint32) and length fields (uint64)
		b.uint16(zipVersion45)           // version made by
		b.uint16(zipVersion45)           // version needed to extract
		b.uint32(0)                      // number of this disk
		b.uint32(0)                      // number of the disk with the start of the central directory

<!--{
	"Title": "The Go Memory Model",
	"Subtitle": "Version of June 6, 2022",
	"Path": "/ref/mem"
}-->

<style>
p.rule {
  font-style: italic;
}
</style>

<h2 id="introduction">Introduction</h2>

<p>
The Go memory model specifies the conditions under which
reads of a variable in one goroutine can be guaranteed to
observe values produced by writes to the same variable in a different goroutine.
</p>

func Check(t *testing.T) {
	checkFiles, err := filepath.Glob(filepath.Join(testenv.GOROOT(t), "api/go1*.txt"))
	if err != nil {
		t.Fatal(err)
	}

	var nextFiles []string
	if v := runtime.Version(); strings.Contains(v, "devel") || strings.Contains(v, "beta") {
		next, err := filepath.Glob(filepath.Join(testenv.GOROOT(t), "api/next/*.txt"))
		if err != nil {
			t.Fatal(err)
		}
		nextFiles = next
	}