Best way to simulate C-assert using gfortran

["Tilo Schwarz" <tilo at tilo-schwarz dot de>]

Hi,

I'm looking for a way to simulate C-assert using gfortran:

1. It should only generate code if NDEBUG is not defined (or some switch  
is set/unset).
2. It should dump core (to inspect the problem in gdb), if the assertion  
does not hold.
3. It should work in pure function too.

I did search google, but without real success.

Since pure functions can't call abort, I finally came up with generating a  
floating point exception triggering the core dump (see below).

Now my questions are:

1. Is there a nicer way to get the same result, maybe using pure Fortran?
2. Is there maybe a trick which could be used specifically with gfortran  
(maybe some gfortran/gcc intrinsic)?

Thanks!
Tilo


% cat prg_assert.f08
#ifdef NDEBUG
#define assert(expr)
#else
#define assert(expr)    call assertion(expr)
#endif

program test
    implicit none

    real r(3), s(3)

    s = [2.0, 1.0, 0.0]
    r = f(s)
    print *, r

contains

    elemental real function f(x)
        implicit none
        real, intent(in) :: x
        assert(x > 0)
        f = x
    end function f

    pure subroutine assertion(cond)
        implicit none
        logical, intent(in) :: cond
        real, volatile :: r
        r = 1.0
        if (.not. cond) r = r / 0.0
    end subroutine assertion

end program test

% gfortran -ffpe-trap=zero -cpp -DNDEBUG prg_assert.f08; a.out
   2.00000000       1.00000000       0.00000000

% gfortran -ffpe-trap=zero -cpp prg_assert.f08; a.out

Program received signal SIGFPE: Floating-point exception - erroneous  
arithmetic operation.

Backtrace for this error:
#0  0xB7605503
#1  0xB7605BA0
#2  0xB76F23FF
#3  0x80486AD in assertion.1800 at prg_assert.f08:0
#4  0x80487C1 in f.1803 at prg_assert.f08:0
#5  0x80486F4 in MAIN__ at prg_assert.f08:0
Floating point exception (core dumped)