[Bug c++/93958] New: gcc trunk supports -std=c++20 but not -std=gnu++20

[romain.geissler at amadeus dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93958

            Bug ID: 93958
           Summary: gcc trunk supports -std=c++20 but not -std=gnu++20
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: romain.geissler at amadeus dot com
  Target Milestone: ---

Hi,

Quite simple (and not important) "bug" report, recently Jason added the support
of -std=c++20 (instead of -std=c++2a), but it looks like the gnu counter part
-std=gnu++20 is not allowed.

# This works:
g++ -std=c++20 -o /dev/null -x c++ -c - <<<""

# This doesn't:
g++ -std=gnu++20 -o /dev/null -x c++ -c - <<<""
g++: error: unrecognized command-line option ‘-std=gnu++20’; did you mean
‘-std=gnu++2a’?

Cheers,
Romain