Warnings

-W
Turn on all warnings.
-Werror
Turn warnings into errors. Note that this option alone doesn’t turn on any warnings; it only affects those warnings that have been turned on so far or will be turned on later.
-W<warning>
Turn on warning.
-Wno-<warning>
Turn off warning.
-Werror-<warning>
Turn on warning and treat it as an error (this implies -W<warning>).
-Wno-error-<warning>
Don’t treat this particular warning as an error. This doesn’t turn off the warning itself.

re2c has the following warnings: