invoking the C compiler to compile the C parts of the package.

The following options are available when running cgo directly:

	-V
		Print cgo version and exit.
	-debug-define
		Debugging option. Print #defines.
	-debug-gcc
		Debugging option. Trace C compiler execution and output.
	-dynimport file
		Write list of symbols imported by file. Write to
		-dynout argument or to standard output. Used by go

	off      int    // read at &buf[off], write at &buf[len(buf)]
	lastRead readOp // last read operation, so that Unread* can work correctly.
}

// The readOp constants describe the last action performed on
// the buffer, so that UnreadRune and UnreadByte can check for
// invalid usage. opReadRuneX constants are chosen such that
// converted to int they correspond to the rune size that was read.
type readOp int8

	// Uname should give a user name.
	Uname() (string, error)
	// Gname should give a group name.
	Gname() (string, error)
}

// isHeaderOnlyType checks if the given type flag is of the type that has no
// data section even if a size is specified.
func isHeaderOnlyType(flag byte) bool {
	switch flag {
	case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo:
		return true
	default:
		return false
	}

files are treated as directives for the test's main package.
In any other context, `//go:debug` lines are ignored by the toolchain;
`go` `vet` reports such lines as misplaced.

## GODEBUG History {#history}

This section documents the GODEBUG settings introduced and removed in each major Go release
for compatibility reasons.
Packages or programs may define additional settings for internal debugging purposes;
for example,

</p>

<p>
Global data symbols are defined by a sequence of initializing
<code>DATA</code> directives followed by a <code>GLOBL</code> directive.
Each <code>DATA</code> directive initializes a section of the
corresponding memory.
The memory not explicitly initialized is zeroed.
The general form of the <code>DATA</code> directive is

<pre>
DATA	symbol+offset(SB)/width, value
</pre>

<p>

		}
	}
}

// handleRegularFile sets up the current file reader and padding such that it
// can only read the following logical data section. It will properly handle
// special headers that contain no data section.
func (tr *Reader) handleRegularFile(hdr *Header) error {
	nb := hdr.Size
	if isHeaderOnlyType(hdr.Typeflag) {
		nb = 0
	}
	if nb < 0 {
		return ErrHeader
	}

//	         if v is nil, len(v) is zero.
//
// For some arguments, such as a string literal or a simple array expression, the
// result can be a constant. See the Go language specification's "Length and
// capacity" section for details.
func len(v Type) int

// The cap built-in function returns the capacity of v, according to its type:
//
//	Array: the number of elements in v (same as len(v)).

	if tw.err != nil {
		return tw.err
	}

	// Trailer: two zero blocks.
	err := tw.Flush()
	for i := 0; i < 2 && err == nil; i++ {
		_, err = tw.w.Write(zeroBlock[:])
	}

	// Ensure all future actions are invalid.
	tw.err = ErrWriteAfterClose
	return err // Report IO errors
}

// regFileWriter is a fileWriter for writing data to a regular file entry.
type regFileWriter struct {

is documented in the “Synchronization” section below.
Individual packages are responsible for providing similar documentation
for their own operations.
</p>

<h2 id="restrictions">Implementation Restrictions for Programs Containing Data Races</h2>

<p>
The preceding section gave a formal definition of data-race-free program execution.
This section informally describes the semantics that implementations must provide