if sign > 0 {
			r = appendClass(r, tmp)
		} else {
			r = appendNegatedClass(r, tmp)
		}
	}
	return r, t, nil
}

// parseClass parses a character class at the beginning of s
// and pushes it onto the parse stack.
func (p *parser) parseClass(s string) (rest string, err error) {
	t := s[1:] // chop [
	re := p.newRegexp(OpCharClass)
	re.Flags = p.flags
	re.Rune = re.Rune0[:0]

				// linux/ppc64 not supported because it does
				// not support external linking mode yet.
				return true
			default:
				// Other targets do not support -shared,
				// per ParseFlags in
				// cmd/compile/internal/base/flag.go.
				// For c-archive the Go tool passes -shared,
				// so that the result is suitable for inclusion
				// in a PIE or shared library.
				return false
			}