When the Go tool sees that one or more Go files use the special import
"C", it will look for other non-Go files in the directory and compile
them as part of the Go package. Any .c, .s, .S or .sx files will be
compiled with the C compiler. Any .cc, .cpp, or .cxx files will be
compiled with the C++ compiler. Any .f, .F, .for or .f90 files will be
compiled with the fortran compiler. Any .h, .hh, .hpp, or .hxx files will

	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'

Go 1.20 removed the preinstalled `.a` files for the standard library
from the Go distribution.
Installations now build and cache the standard library like
packages in other modules.
The [`installgoroot` setting](/cmd/go#hdr-Compile_and_install_packages_and_dependencies)
restores the installation and use of preinstalled `.a` files.

There is no plan to remove any of these settings.

### Go 1.19

<pre>
PCALIGN $32
MOVD $2, R0
</pre>
</p>

<h3 id="data-offsets">Interacting with Go types and constants</h3>

<p>
If a package has any .s files, then <code>go build</code> will direct
the compiler to emit a special header called <code>go_asm.h</code>,
which the .s files can then <code>#include</code>.
The file contains symbolic <code>#define</code> constants for the
offsets of Go struct fields, the sizes of Go struct types, and most

	}
	s := buf.String()
	zr, err := NewReader(strings.NewReader(s), int64(len(s)))
	if err != nil {
		t.Fatalf("NewReader: %v", err)
	}
	if got := len(zr.File); got != nFiles {
		t.Fatalf("File contains %d files, want %d", got, nFiles)
	}
	for i := 0; i < nFiles; i++ {
		want := fmt.Sprintf("%d.dat", i)
		if zr.File[i].Name != want {
			t.Fatalf("File(%d) = %q, want %q", i, zr.File[i].Name, want)
		}
	}
}

	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 {

		}
	}
}

func Benchmark(b *testing.B) {
	type file struct {
		hdr  *Header
		body []byte
	}

	vectors := []struct {
		label string
		files []file
	}{{
		"USTAR",
		[]file{{
			&Header{Name: "bar", Mode: 0640, Size: int64(3)},
			[]byte("foo"),
		}, {
			&Header{Name: "world", Mode: 0640, Size: int64(5)},
			[]byte("hello"),
		}},

func (w *Writer) RegisterCompressor(method uint16, comp Compressor) {
	if w.compressors == nil {
		w.compressors = make(map[uint16]Compressor)
	}
	w.compressors[method] = comp
}

// AddFS adds the files from fs.FS to the archive.
// It walks the directory tree starting at the root of the filesystem
// adding each file to the zip using deflate while maintaining the directory structure.
func (w *Writer) AddFS(fsys fs.FS) error {

		"subfolder/another.go": {Data: []byte("world")},
	}
	var buf bytes.Buffer
	tw := NewWriter(&buf)
	if err := tw.AddFS(fsys); err != nil {
		t.Fatal(err)
	}

	// Test that we can get the files back from the archive
	tr := NewReader(&buf)

	entries, err := fsys.ReadDir(".")
	if err != nil {
		t.Fatal(err)
	}

	var curfname string
	for _, entry := range entries {