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

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

[wjwray at gmail dot com]

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'

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

[mpolacek at gcc dot gnu.org]

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

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
                 CC|                            |mpolacek at gcc dot gnu.org
   Last reconfirmed|                            |2021-03-08

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
get_cxx_dialect_name doesn't handle C++23 yet.  Looks like Nathan is on it.

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

[nathan at gcc dot gnu.org]

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

--- Comment #2 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
indeed, also enabling modules test in 2b mode

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

[cvs-commit at gcc dot gnu.org]

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

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathan Sidwell <nathan@gcc.gnu.org>:

https://gcc.gnu.org/g:4b3d86a7768a7562798f17f074f540fbc288ec3b

commit r11-7575-g4b3d86a7768a7562798f17f074f540fbc288ec3b
Author: Nathan Sidwell <nathan@acm.org>
Date:   Tue Mar 9 05:08:09 2021 -0800

    c++: Clarify note about -fmodules-ts [PR 99472]

    This clarifies that c++2[03] intentionally does not enable
    c++20 modules.

            PR c++/99472
            gcc/cp/
            * parser.c (cp_parser_diagnose_invalid_type_name): Clarify
            that C++20 does not yet imply modules.

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

[nathan at gcc dot gnu.org]

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

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #4 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
 4b3d86a7768 2021-03-09 | c++: Clarify note about -fmodules-ts [PR 99472]

it is intentional