}

		// While not recommended, it is valid to append to a shifted buffer.
		// This forces Write to copy the input.
		if rn.Intn(8) == 0 && cap(b) > 0 {
			b = b[1:1:cap(b)]
		}

		// Append a random integer of varying width.
		n := int64(rn.Intn(1 << rn.Intn(30)))
		want = append(strconv.AppendInt(want, n, 10), ' ')
		b = append(strconv.AppendInt(b, n, 10), ' ')
		w.Write(b)
	}
	w.Flush()

	const (
		notType = 1 << iota
		notIntConst
		notNumConst
		notStrLiteral
		notDeclared
	)
	sawUnmatchedErrors := false
	for _, line := range strings.Split(stderr, "\n") {
		// Ignore warnings and random comments, with one
		// exception: newer GCC versions will sometimes emit
		// an error on a macro #define with a note referring
		// to where the expansion occurs. We care about where