const (
	reserved = 0
	allBytes = ^uint32(0)
)

func lock(f File, lt lockType) error {
	// Per https://golang.org/issue/19098, “Programs currently expect the Fd
	// method to return a handle that uses ordinary synchronous I/O.”
	// However, LockFileEx still requires an OVERLAPPED structure,
	// which contains the file offset of the beginning of the lock range.
	// We want to lock the entire file, so we leave the offset as zero.

	"builtin": true,

	// go.dev/issue/46027: some imports are missing for this submodule.
	"crypto/internal/edwards25519/field/_asm": true,
	"crypto/internal/bigmod/_asm":             true,
}

// printPackageMu synchronizes the printing of type-checked package files in
// the typecheckFiles function.
//
// Without synchronization, package files may be interleaved during concurrent
// type-checking.
var printPackageMu sync.Mutex

and the [go command documentation](/cmd/go#hdr-Build_and_test_caching).

### Go 1.23

Go 1.23 changed the channels created by package time to be unbuffered
(synchronous), which makes correct use of the [`Timer.Stop`](/pkg/time/#Timer.Stop)
and [`Timer.Reset`](/pkg/time/#Timer.Reset) method results much easier.
The [`asynctimerchan` setting](/pkg/time/#NewTimer) disables this change.

	lv.livevars = lv.livevars[:0]
}

func (lv *liveness) enableClobber() {
	// The clobberdead experiment inserts code to clobber pointer slots in all
	// the dead variables (locals and args) at every synchronous safepoint.
	if !base.Flag.ClobberDead {
		return
	}
	if lv.fn.Pragma&ir.CgoUnsafeArgs != 0 {
		// C or assembly code uses the exact frame layout. Don't clobber.
		return
	}