[Bug c++/99472] New: [modules] std=c++2b flag appears incompatible with C++20 module code

[wjwray at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99472

            Bug ID: 99472
           Summary: [modules] std=c++2b flag appears incompatible with
                    C++20 module code
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: wjwray at gmail dot com
  Target Milestone: ---

Same as bug 99436, submitting with [modules] subject and CE link
https://godbolt.org/z/8ME9d8

export module foo;

This works: -std=c++20 -fmodules-ts

This fails: -std=c++2b -fmodules-ts
    -> ICE

This fails: -std=c++2b
    -> warning: keyword 'export' is enabled with '-fmodules-ts'