func C.GoBytes(unsafe.Pointer, C.int) []byte

As a special case, C.malloc does not call the C library malloc directly
but instead calls a Go helper function that wraps the C library malloc
but guarantees never to return nil. If C's malloc indicates out of memory,
the helper function crashes the program, like when Go itself runs out
of memory. Because C.malloc cannot fail, it has no two-result form
that returns errno.

pkg testing, method (*F) Failed() bool
pkg testing, method (*F) Fatal(...interface{})
pkg testing, method (*F) Fatalf(string, ...interface{})
pkg testing, method (*F) Fuzz(interface{})
pkg testing, method (*F) Helper()
pkg testing, method (*F) Log(...interface{})
pkg testing, method (*F) Logf(string, ...interface{})
pkg testing, method (*F) Name() string
pkg testing, method (*F) Setenv(string, string)

pkg syscall, type RawConn interface, Read(func(uintptr) bool) error
pkg syscall, type RawConn interface, Write(func(uintptr) bool) error
pkg testing, method (*B) Helper()
pkg testing, method (*T) Helper()
pkg testing, type TB interface, Helper()
pkg time, method (Duration) Round(Duration) Duration