message: [FormatManager] Add static_assert to keep formats in sync.
  This adds a static assert that ensures that there's a format info entry
  for every format enum value. This should prevent others from making the
  same mistake I made and Jason kindly fixed in r369611. (Thanks!)
diff: @@ -30,7 +30,7 @@ struct FormatInfo {
  // current format
  };
  -static FormatInfo g_format_infos[] = {
  +static constexpr FormatInfo g_format_infos[] = {
  {eFormatDefault, '\0', "default"},
  {eFormatBoolean, 'B', "boolean"},
  {eFormatBinary, 'b', "binary"},
  @@ -72,6 +72,10 @@ static FormatInfo g_format_infos[] = {
  {eFormatInstruction, 'i', "instruction"},
  {eFormatVoid, 'v', "void"}};
  +static_assert((sizeof(g_format_infos) / sizeof(g_format_infos[0])) ==
  + kNumFormats,
  + "All formats must have a corresponding info entry.");
  +
  static uint32_t g_num_format_infos = llvm::array_lengthof(g_format_infos);
  static bool GetFormatFromFormatChar(char format_char, Format &format) {
  