[Bug libstdc++/98319] New: LFTS headers give errors if included as C++11 or C++98

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98319

            Bug ID: 98319
           Summary: LFTS headers give errors if included as C++11 or C++98
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

For example:

/home/jwakely/gcc/11/include/c++/11.0.0/experimental/source_location: In static
member function ‘static constexpr
std::experimental::fundamentals_v2::source_location
std::experimental::fundamentals_v2::source_location::current(const char*, const
char*, int, int)’:
/home/jwakely/gcc/11/include/c++/11.0.0/experimental/source_location:63:5:
error: body of ‘constexpr’ function ‘static constexpr
std::experimental::fundamentals_v2::source_location
std::experimental::fundamentals_v2::source_location::current(const char*, const
char*, int, int)’ not a return-statement

It should be possible to include them and then test the feature test macro to
see if they are usable.