REG_ECTYPE
(void)REQUIRE(c != '-' && c != ']', REG_ECTYPE);
(void)REQUIRE(EATTWO(':', ']'), REG_ECTYPE);
SETERROR(REG_ECTYPE);
SETERROR(REG_ECTYPE);
{REG_ECTYPE, "REG_ECTYPE", "invalid character class"},