[Bug middle-end/64334] New: Common .opt handling: Support flags which take a list of values (-fopt=a,b,c ...)

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64334

            Bug ID: 64334
           Summary: Common .opt handling: Support flags which take a list
                    of values (-fopt=a,b,c ...)
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: manu at gcc dot gnu.org
            Blocks: 54687

Split off from PR54687.

There are some options which take a list of values – and applies bitwise OR to
the choice.

Example:
  fsanitize=
which takes "address" (SANITIZE_ADDRESS | SANITIZE_USER_ADDRESS),
"kernel-address" (SANITIZE_ADDRESS | SANITIZE_KERNEL_ADDRESS), "thread"
(SANITIZE_THREAD) etc. as argument.

Similarly, in Fortran: -ffpe-trap and -ffpe-summary which take "invalid",
"denormal" etc. or -fcheck= with "all", "bounds", ...

It would be useful it one could extend the current Enum scheme to support this.