On Fri, Oct 06, 2017 at 09:30:06PM -0700, Jerry DeLisle wrote:
> On 10/06/2017 01:34 PM, Steve Kargl wrote:
> > All,
> >
> > I have spent the last few days trying to reconcile the various Fortran
> > standards' requirements for handling BOZ. The short story is that J3
> > over the last 27 years has made incompatible changes to the interpretation
> > of a BOZ (under some circumstances). The interpretations in F2008 and
> > F2015 now treat a boz-literal-constant as a sequence of bits.
> > Unfortunately,
> > due to quirks in how BOZ are currently implemented in gfortran and a boat
> > load of documented and undocumented extensions, bringing gfortran into
> > agreement with F2008/F2015 led to a rewrite of BOZ handling. In the
> > rewrite I have made no attempt to use the -std= option to try to maintain
> > the incompatibilities between standards.
> >
>
> The patch tests OK on trunk with linux-x86_64. I suggest this be
> committed as is and then see if there is any fallout that can be
> dealt with -std=legacy or similar later.
>
Thanks, but unfortunately in my review of the patch and F2008/F2015
found an issue.
integer :: i = int(z'123456789',4)
isn't handled correctly. We do get a silly error.
% gfcx -c a.f90
a.f90:1:19:
integer :: i = int(z'123456789',4)
1
Error: Arithmetic overflow converting INTEGER(-1) to INTEGER(4) at (1).
This check can be disabled with the option '-fno-range-check'
F2008 13.3.3 has
When a boz-literal-constant is the argument A of the intrinsic
function INT or REAL,
...
if the length of the sequence of bits specified by A is greater
than the size in bits of a scalar variable of the same type and
kind type parameter as the result, the boz-literal-constant is
treated as if it were truncated from the left to a length equal
to the size in bits of the result.
C1301 If a boz-literal-constant is truncated as an argument to
the intrinsic function REAL, the discarded bits shall all be zero.
We handle C1301 correctly except the error message could be better.
% gfcx -c a.f90
a.f90:1:17:
real :: i = real(z'123456789',4)
1
Error: BOZ constant at (1) is too large (33 vs 32 bits)
--
Steve
20170425 https://www.youtube.com/watch?v=VWUpyCsUKR4
20161221 https://www.youtube.com/watch?v=IbCHE-hONow
