[Bug fortran/54298] New: Add warning when doing equal/nonequal floating-point comparisons

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54298

             Bug #: 54298
           Summary: Add warning when doing equal/nonequal floating-point
                    comparisons
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org


Suggested by ISO/IEC Project 22.24772 "Guidance for Avoiding Vulnerabilities
through Language Selection and Use"  (see links at
http://gcc.gnu.org/wiki/GFortranStandards)

>From the Fortran appendix (draft at
http://grouper.ieee.org/groups/plv/DocLog/400-499/400-419/22-WG23-N-0410/n0410.pdf)


"Fortran.5 Floating-point Arithmetic [PFL]
...
"Fortran.5.2 Guidance to Fortran Users"
...
"* Do not create a logical value from a test for equality or inequality between
two floating-point expressions. Use compiler options where available to detect
such a usage"


gfortran doesn't have such a warning.