}
			if h.Typeflag == TypeGNUSparse {
				whyOnlyGNU = "only GNU supports TypeGNUSparse"
				format.mayOnlyBe(FormatGNU)
			} else {
				whyNoGNU = "GNU supports sparse files only with TypeGNUSparse"
				format.mustNotBe(FormatGNU)
			}
			whyNoUSTAR = "USTAR does not support sparse files"
			format.mustNotBe(FormatUSTAR)
		}
	*/

	// Check desired format.

		// Always copy directories (don't symlink them).
		// If we add a file in the overlay, we don't want to add it in the original.
		if info.IsDir() {
			return os.MkdirAll(dstPath, perm|0200)
		}

		// If the OS supports symlinks, use them instead of copying bytes.
		if err := os.Symlink(srcPath, dstPath); err == nil {
			return nil
		}

		// Otherwise, copy the bytes.
		src, err := os.Open(srcPath)
		if err != nil {

This behavior was backported to Go 1.19.8+ and Go 1.20.3+.

Go 1.21 adds the support of Multipath TCP but it is only used if the application
explicitly asked for it. This behavior can be controlled by the
[`multipathtcp` setting](/pkg/net#Dialer.SetMultipathTCP).

There is no plan to remove any of these settings.

### Go 1.20

Go 1.20 introduced support for rejecting insecure paths in tar and zip archives,

)

// A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker,
// io.ByteScanner, and io.RuneScanner interfaces by reading from
// a byte slice.
// Unlike a [Buffer], a Reader is read-only and supports seeking.
// The zero value for Reader operates like a Reader of an empty slice.
type Reader struct {
	s        []byte
	i        int64 // current reading index
	prevRune int   // index of previous rune; or < 0
}

must support both internal and external linking, depending on the
circumstances: if net is the only cgo-using package, then internal
linking is probably fine, but if other packages are involved, so that there
are dependencies on libraries beyond libc, external linking is likely
to work better. The compilation of a package records the relevant
information to support both linking modes, leaving the decision

//
// The table's lower portion shows specialized features of each format,
// such as supported string encodings, support for sub-second timestamps,
// or support for sparse files.
//
// The Writer currently provides no support for sparse files.
type Format int

// Constants to identify various tar formats.
const (
	// Deliberately hide the meaning of constants from public API.

<!-- go.dev/issue/64207 -->
As [announced](go1.22#darwin) in the Go 1.22 release notes,
Go 1.23 requires macOS 11 Big Sur or later;
support for previous versions has been discontinued.

### Wasm {#wasm}

<!-- go.dev/issue/63718 -->
The `go_wasip1_wasm_exec` script in `GOROOT/misc/wasm` has dropped support

	if err != nil {
		t.Skipf("swig not in PATH: %s", err)
	}

	// Check that swig was installed with Go support by checking
	// that a go directory exists inside the swiglib directory.
	// See https://golang.org/issue/23469.
	output, err := exec.Command(swig, "-go", "-swiglib").Output()
	if err != nil {
		t.Skip("swig is missing Go support")
	}
	swigDir := strings.TrimSpace(string(output))

	SYNC		// 0000000f

//
// NOP
//
//	LNOP comma // asm doesn't support the trailing comma.
//	{
//		outcode(int($1), &nullgen, 0, &nullgen);
//	}
	NOP

//	LNOP rreg comma // asm doesn't support the trailing comma.
//	{
//		outcode(int($1), &$2, 0, &nullgen);
//	}
	NOP R2

//	LNOP freg comma // asm doesn't support the trailing comma.
//	{
//		outcode(int($1), &$2, 0, &nullgen);
//	}

	const bufSize = 16 << 10
	buf := make([]byte, bufSize)
	r := bytes.NewReader(buf)
	srcReader := NewReaderSize(onlyReader{r}, 1<<10)
	if _, ok := io.Discard.(io.ReaderFrom); !ok {
		b.Fatal("io.Discard doesn't support ReaderFrom")
	}
	for i := 0; i < b.N; i++ {
		r.Seek(0, io.SeekStart)
		srcReader.Reset(onlyReader{r})
		n, err := srcReader.WriteTo(io.Discard)
		if err != nil {
			b.Fatal(err)
		}