[Bug c++/99274] New: [modules] Error when compiling some system headers as modules after <iosfwd>

[Bug c++/99274] New: [modules] Error when compiling some system headers as modules after <iosfwd>

[alexander.lelyakin at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99274

            Bug ID: 99274
           Summary: [modules] Error when compiling some system headers as
                    modules after <iosfwd>
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alexander.lelyakin at googlemail dot com
  Target Milestone: ---

Some system headers cannot be compiled as a modules after you compile <ioswfd>
At least <future> and <complex>:
-----
g++ -std=c++20 -fmodules-ts -x c++-system-header iosfwd
g++ -std=c++20 -fmodules-ts -x c++-system-header future
-----
In file included from /usr/local/include/c++/11.0.1/string:43,
                 from /usr/local/include/c++/11.0.1/stdexcept:39,
                 from /usr/local/include/c++/11.0.1/system_error:41,
                 from /usr/local/include/c++/11.0.1/mutex:42,
                 from /usr/local/include/c++/11.0.1/future:38:
/usr/local/include/c++/11.0.1/bits/localefwd.h:156:74: error: wrong number of
template arguments (1, should be 2)
  156 |   template<typename _CharT, typename _InIter =
istreambuf_iterator<_CharT> >
      |                                                                        
 ^
.....

----
g++ -std=c++20 -fmodules-ts -x c++-system-header iosfwd
g++ -std=c++20 -fmodules-ts -x c++-system-header complex
----
In file included from /usr/local/include/c++/11.0.1/ios:41,
                 from /usr/local/include/c++/11.0.1/istream:38,
                 from /usr/local/include/c++/11.0.1/sstream:38,
                 from /usr/local/include/c++/11.0.1/complex:45:
/usr/local/include/c++/11.0.1/bits/localefwd.h:156:74: error: wrong number of
template arguments (1, should be 2)
  156 |   template<typename _CharT, typename _InIter =
istreambuf_iterator<_CharT> >
      |                                                                        
 ^
In file included from /usr/local/include/c++/11.0.1/bits/specfun.h:45,
                 from /usr/local/include/c++/11.0.1/cmath:1927,
                 from /usr/local/include/c++/11.0.1/complex:44:
/usr/local/include/c++/11.0.1/bits/stl_algobase.h:451:11: note: provided for
‘template<class _CharT, class _Traits> class std::istreambuf_iterator’
..........

[Bug c++/99274] [modules] Error compiling some system headers: "wrong number of template arguments (1, should be 2)"

[alexander.lelyakin at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99274

--- Comment #1 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> ---
Previously I have seen such message only in connection with <iosfwd>,
but it happends also without it. 
Another header causing such error is <regex>:

g++ -std=c++20 -fmodules-ts -x c++-system-header iterator
g++ -std=c++20 -fmodules-ts -x c++-system-header regex
----
In file included from /usr/local/include/c++/11.0.1/locale:40,
                 from /usr/local/include/c++/11.0.1/regex:44:
/usr/local/include/c++/11.0.1/bits/locale_facets.h:121:31: error: wrong number
of template arguments (1, should be 2)
  121 |     ostreambuf_iterator<_CharT>
      |                               ^
In file included from /usr/local/include/c++/11.0.1/algorithm:61,
                 from /usr/local/include/c++/11.0.1/regex:38:
/usr/local/include/c++/11.0.1/bits/stl_algobase.h:454:11: note: provided for
‘template<class _CharT, class _Traits> class std::ostreambuf_iterator’
  454 |     class ostreambuf_iterator;
      |           ^~~~~~~~~~~~~~~~~~~
In file included from /usr/local/include/c++/11.0.1/locale:40,
                 from /usr/local/include/c++/11.0.1/regex:44:
/usr/local/include/c++/11.0.1/bits/locale_facets.h:122:39: error: wrong number
of template arguments (1, should be 2)
  122 |     __write(ostreambuf_iterator<_CharT> __s, const _CharT* __ws, int
__len)
      |                                       ^
In file included from /usr/local/include/c++/11.0.1/algorithm:61,
                 from /usr/local/include/c++/11.0.1/regex:38:
/usr/local/include/c++/11.0.1/bits/stl_algobase.h:454:11: note: provided for
‘template<class _CharT, class _Traits> class std::ostreambuf_iterator’
  454 |     class ostreambuf_iterator;
      |           ^~~~~~~~~~~~~~~~~~~
In file included from /usr/local/include/c++/11.0.1/locale:40,
                 from /usr/local/include/c++/11.0.1/regex:44:
/usr/local/include/c++/11.0.1/bits/locale_facets.h: In function ‘int
std::__write(int, const _CharT*, int)’:
/usr/local/include/c++/11.0.1/bits/locale_facets.h:124:11: error: request for
member ‘_M_put’ in ‘__s’, which is of non-class type ‘int’
  124 |       __s._M_put(__ws, __len);
      |           ^~~~~~
/usr/local/include/c++/11.0.1/regex: At global scope:
/usr/local/include/c++/11.0.1/regex: warning: not writing module
‘/usr/local/include/c++/11.0.1/regex’ due to errors
----
g++ (GCC) 11.0.1 20210312 (experimental)
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Bug c++/99274] [modules] Error compiling some system headers: "wrong number of template arguments (1, should be 2)"

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99274

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-06-05
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1