Re: Fortran 9x: time for a decision

[Steven G. Johnson]

Steven G. Johnson wrote:
> (1) Have two compilers, F77 and FXX, where the former tries to be F77
> (i.e. the current behavior) while the latter is selected by
> AC_PROG_FXX([year], [search-list]), where year is YY or YYYY with YY < 54
> interpreted as 20YY, and with the default year being the latest supported
> Fortran standard.  Unknown years trigger an error.  (Have $FXXFLAGS etc.
> in analogue to $FFLAGS etc.)  Rationales:

To clarify, AC_PROG_FXX(YEAR) would look for a Fortran compiler starting 
with YEAR, and then looking at later years if YEAR is not found.  e.g. 
AC_PROG_FXX(77) would find the same compiler as AC_PROG_F77 does now.

If YEAR is not specified, then it would look for Fortran compilers in 
reverse order of time, i.e. looking for the newest standard first.  This 
is what most people who are not compiling legacy codes will probably 
want: "give me the latest and greatest."  (This is the way other 
languages are treated, after all.)

(I don't think it should be the purpose of AC_PROG_FXX to guarantee 
particular language features, since these can't always be inferred from 
the compiler name; also, this is not done by e.g. AC_PROG_CXX.  Other 
autoconf tests can be written for that purpose, if necessary.  The YEAR 
argument is only there to try to force the use of an older compiler (but 
not too old) even if a newer one is present, i.e. to reverse the usual 
preferences, in case the user is employing obsolete syntax.)

Steven