https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52279
--- Comment #8 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Thu, Jul 02, 2020 at 03:53:22PM +0000, jakub at gcc dot gnu.org wrote: > > --- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > (In reply to kargl from comment #6) > > There is no -fno-allow-invalid-boz option. The option is > > -fallow-invalid-boz. fortan/lang.opt defines the options > > with the RejectNegative annotation. > > Why is it RejectNegative? Because there is nothing to negate. real :: x = z'1234' end is an invalid use of a BOZ. gfortran 10.1 will issue an error for this construct (and a number of previously documented and undocumented extensions). Unfortunately, older vesions of gfortran accepted the above without error or warning. When I fixed gfortran's handling of BOZ to conform to the Fortran 2008/2018 standard (i.e., emit an error for the above code), I introduced -fallow-invalid-boz to down-grade the error to a warning, so that older codes will compile. gfortran -c a.f90 <-- error gfortran -c -fallow-invalid-boz a.f90 <-- warning gfortran -c -fallow-invalid-boz -fno-allow-invalid-boz a.f90 <-- stupidity > Is there some other option that acts as it negative option? IMO, there is nothing to negative. If you don't want the option, then don't use it. > If it is just a standalone boolean option, it should have a negative, > so that if e.g. one uses -fallow-invalid-boz in $FFLAGS for most of > files in some project, but there is a specific one that shouldn't > allow it, one can just append -fno-allow-invalid-boz for it to cancel > the earlier option. This makes no sense to me. gfortran will accept valid uses of a BOZ without any option. If you add -fallow-invalid-boz to $FFLAGS, then you're simply accepting invalid Fortran (with a warning) in addition to valid Fortran. If a programmer is adding a new file to a project and $FFLAGS includes -fallow-invalid-boz, then programmer will get a warning about invalid code instead of an error. The programmer is informed about the issue, and can make the necessary change, e.g., real :: x = real(z'1234', 4) end in the new file. The point of the option is to allow backwards compatibility, but to be verbose about the invalid Fortran; hopefully, to encourage the programmer to fix their code.
