Re: [PATCH, gfortran testsuite]: Do not load denormals in gfortran.fortran_torture/intrinsic_nearest.f90

["N.M. Maclaren" <nmm1 at cam dot ac dot uk>]

On Aug 23 2009, Tim Prince wrote:

> I ran into a peculiarity with gfortran C interoperability.  It throws a 
> fatal KIND mismatch, as KIND(.false.) is 4, and KIND(c_bool) is 1.  I 
> assumed that IEEE_SET_UNDERFLOW_MODE(gradual) should work with
> logical(c_bool) :: gradual
> Have I gone wrong in my assumption, or does the standard require
> CALL IEEE_SET_UNDERFLOW_MODE(LOGICAL(.false.,KIND(C_BOOL)))
> if IEEE_SET_UNDERFLOW is written according to iso_c_interop  ?

Oh, gosh, you really do need a copy of the standard to work from.  IEEE
support has nothing to do with C interoperability.  IEEE_SET_UNDERFLOW_MODE
etc. are intrinsics, and follow whatever rules Fortran specifies - NOT
necessarily ones that any normal procedure can follow - in this case, its
argument is specified to be a default LOGICAL scalar, so you should be using
just .FALSE.

So a fatal KIND mismatch is correct for C_BOOL.  Incidentally, as a general
rule, avoid C99 bool like the plague - it's a lot safer to stick to int,
in the traditional way.

Regards,
Nick Maclaren.