[Bug other/110032] New: Option Alias(opt, posarg, negarg) doesn't accept multi args for posarg

["crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110032

            Bug ID: 110032
           Summary: Option Alias(opt, posarg, negarg) doesn't accept multi
                    args for posarg
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: crazylht at gmail dot com
  Target Milestone: ---

.i.e.

If define

fcf-protection
Common RejectNegative Alias(fcf-protection=,branch, return)

fcf-protection=
Common Joined  Enum(cf_protection_level) EnumBitset Var(flag_cf_protection)
-fcf-protection=[full|branch|return|none|check] Instrument functions with
checks to verify jump/call/return control-flow transfer
instructions have valid targets.

Enum
Name(cf_protection_level) Type(enum cf_protection_level) UnknownError(unknown
Control-Flow Protection Level %qs)

EnumValue
Enum(cf_protection_level) String(branch) Value(CF_BRANCH)

EnumValue
Enum(cf_protection_level) String(return) Value(CF_RETURN)

EnumValue
Enum(cf_protection_level) String(check) Value(CF_CHECK)


It will be intepretted as -fcf-protection=branch, but not
-fcf-protection=branch,return. It's due to both Alias and EnumBitSet use *,* as
delimiter and can't tell if it's multi args in EnumBitSet or in Alias posarg.

And yes we can introduce another parameter full to cover all bits but then
EnumBiSet can't be used since it require every parameter to be power of 2.