FEATURE_BIT        67 ruby.c         #define FEATURE_BIT(bit) (1U << feature_##bit)
FEATURE_BIT       150 ruby.c         | FEATURE_BIT(frozen_string_literal)
FEATURE_BIT       151 ruby.c         | FEATURE_BIT(debug_frozen_string_literal)
FEATURE_BIT       154 ruby.c         (FEATURE_BIT(debug_flag_first)-1)
FEATURE_BIT       156 ruby.c         & ~FEATURE_BIT(gems)
FEATURE_BIT       158 ruby.c         & ~FEATURE_BIT(frozen_string_literal)