Re: [patch, fortran] Handling of .and. and .or. expressions

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

On Jun 28 2018, Steve Kargl wrote:
> You continue to miss my point or conveniently ignore it.
> You want to special case the forced evaluation of the
> operands in two specific logical expressions; namely, .and.
> and .or.  If you want to force evaluation of operands, then
> do it for all binary operators. 

It's not just binary operators.  It also includes code like:
   IF (FRED()) CONTINUE
and even:
   X = FRED()
   X = 0.0
There are a zillion other possible ways in which this can arise;
I have certainly seen those optimised out, as well as the constructs
being discussed.

I have no idea how many are currently optimised out by gfortran,
still less how many may be in the future.  Janus would like to know
of compilers that do this sort of thing - the place to look is the
ones sold by the supercomputing companies, like Cray, IBM, Hitachi
and Fujitsu. I don't know how many others still maintain their own
compilers.  I am retired and no longer have access to any of them.

Having a warning for known confusing cases (like .AND.) but not
others is fine.  Lots of warnings are like that.

Having an option that makes a couple of constructs in the language
behave in a way not required by the standard, but not others with
similar properties, merely adds a new gotcha.


Regards,
Nick Maclaren.