// Arenas are useful for improving efficiency as they may be freed back to
// the runtime manually, though any memory obtained from freed arenas must
// not be accessed once that happens. An Arena is automatically freed once
// it is no longer referenced, so it must be kept alive (see runtime.KeepAlive)
// until any memory allocated from it is no longer needed.
//

	// compiled by gcc, into foo.cgo2.o

	void
	_cgo_gcc_Cfunc_sin(void *v)
	{
		struct {
			double p0;
			double r;
		} __attribute__((__packed__)) *a = v;
		a->r = sin(a->p0);
	}

What happens at link time depends on whether the final binary is linked
using the internal or external mode. If other packages are compiled in
"external only" mode, then the final link will be an external one.

the function completes.
(See also the section on <a href="#Handling_panics">handling panics</a>.)
</p>

<pre>
lock(l)
defer unlock(l)  // unlocking happens before surrounding function returns

// prints 3 2 1 0 before surrounding function returns
for i := 0; i &lt;= 3; i++ {
	defer fmt.Print(i)
}

// f returns 42
func f() (result int) {

Instantiation proceeds in two steps:
</p>

<ol>
<li>
Each type argument is substituted for its corresponding type parameter in the generic
declaration.
This substitution happens across the entire function or type declaration,
including the type parameter list itself and any types in that list.
</li>

<li>

	//
	// By specification, the only other encoding permitted should be CP-437,
	// but historically many ZIP readers interpret Name and Comment as whatever
	// the system's local character encoding happens to be.
	//
	// This flag should only be set if the user intends to encode a non-portable
	// ZIP file for a specific localized region. Otherwise, the Writer

		// is type T defined as *X, simulate a little of the
		// laxness of C by making the argument *X instead of T.
		if ptr, ok := base(dt.Type).(*dwarf.PtrType); ok {
			// Unless the typedef happens to point to void* since
			// Go has special rules around using unsafe.Pointer.
			if _, void := base(ptr.Type).(*dwarf.VoidType); void {
				break
			}

which are unordered by happens before
(that is, neither <i>r</i> happens before <i>w</i>
nor <i>w</i> happens before <i>r</i>).
</p>

<p>
A <i>write-write data race</i> on memory location <i>x</i>
consists of two write-like memory operations <i>w</i> and <i>w'</i> on <i>x</i>,
at least one of which is non-synchronizing,
which are unordered by happens before.
</p>

<p>

// A Stack is a stack of TokenReaders. As the top TokenReader hits EOF,
// it resumes reading the next one down.
type Stack struct {
	tr []TokenReader
}

// Push adds tr to the top (end) of the input stack. (Popping happens automatically.)
func (s *Stack) Push(tr TokenReader) {
	s.tr = append(s.tr, tr)
}

func (s *Stack) Next() ScanToken {
	tos := s.tr[len(s.tr)-1]
	tok := tos.Next()
	for tok == scanner.EOF && len(s.tr) > 1 {

// adbCopyGoroot clears deviceRoot for previous versions of GOROOT, GOPATH
// and temporary data. Then, it copies relevant parts of GOROOT to the device,
// including the go tool built for android.
// A lock file ensures this only happens once, even with concurrent exec
// wrappers.
func adbCopyGoroot() error {
	goTool, err := goTool()
	if err != nil {
		return err
	}
	cmd := exec.Command(goTool, "version")
	cmd.Stderr = os.Stderr

		// Nearly every major ZIP implementation uses a different format,
		// but at least most seem to be able to understand the other formats.
		//
		// This format happens to be identical for both local and central header
		// if modification time is the only timestamp being encoded.
		var mbuf [9]byte // 2*SizeOf(uint16) + SizeOf(uint8) + SizeOf(uint32)
		mt := uint32(fh.Modified.Unix())