Hi Janus, The patch is good - OK for trunk.
Thanks Paul On 12 December 2016 at 16:52, Janus Weil <ja...@gcc.gnu.org> wrote: > Hi all, > > I hate to ping this patch once more, but somehow we need to come to a > conclusion here. > > The issue boils down to the fact that there is a piece of code in the > gfortran code which claims that specification functions are > 'constant', but I doubt that this is true. To my understanding the > concept of specification expressions and specification functions (see > section 7.1.6 in the F03 standard) was introduced essentially to refer > to side-effect-free expressions that can be used e.g. in a > type-specification context (array bounds, char-length parameters etc). > > However I think 'specification functions' do not necessarily need to > be 'constants', in the sense that subsequent invocations give always > the same (constant) result and their value can be determined at > compile time. > > My patch is at: https://gcc.gnu.org/ml/fortran/2016-11/msg00188.html > Further discussion at: https://gcc.gnu.org/ml/fortran/2016-11/msg00243.html > > Any comments, please!?! > > Cheers, > Janus > > > > 2016-12-03 8:05 GMT+01:00 Janus Weil <ja...@gcc.gnu.org>: >> double-ping! >> >> >> 2016-11-26 10:45 GMT+01:00 Janus Weil <ja...@gcc.gnu.org>: >>> ping! >>> >>> >>> 2016-11-19 10:12 GMT+01:00 Janus Weil <ja...@gcc.gnu.org>: >>>> Hi all, >>>> >>>>> I previously assumed that the test case for this PR would be legal, >>>>> but by now I think that's wrong. The test case should be rejected, and >>>>> we already have checking mechanisms for this (see >>>>> resolve_fl_variable), but apparently they are not working. >>>>> >>>>> My current suspicion is that 'gfc_is_constant_expr' has a bug, because >>>>> it claims the call to the function 'get_i' to be a constant >>>>> expression. This is not true, because get_i() can not be reduced to a >>>>> compile-time constant. >>>> >>>> some more reading in the standard confirms this suspicion: In >>>> gfc_is_constant_expr there is a piece of code which claims that >>>> specification functions are constant. That is certainly not true, and >>>> so what I'm doing in the attached fix is to remove that code and add >>>> some references to the standard to make things clearer. >>>> >>>> The code that I'm removing has last been touched in this commit by >>>> Jerry six years ago: >>>> >>>> https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=166520 >>>> >>>> However, this did not introduce the bug in the first place (not sure >>>> when that happened). >>>> >>>> In any case the new patch in the attachment regtests cleanly and >>>> correctly rejects the original test case as well as one of the cases >>>> mentioned by Dominique. Ok for trunk? >>>> >>>> Cheers, >>>> Janus >>>> >>>> >>>> >>>> 2016-11-19 Janus Weil <ja...@gcc.gnu.org> >>>> >>>> PR fortran/78392 >>>> * expr.c (gfc_is_constant_expr): Specification functions are not >>>> compile-time constants. Update documentation (add reference to F08 >>>> standard), add a FIXME. >>>> (external_spec_function): Add reference to F08 standard. >>>> * resolve.c (resolve_fl_variable): Ditto. >>>> >>>> 2016-11-19 Janus Weil <ja...@gcc.gnu.org> >>>> >>>> PR fortran/78392 >>>> * gfortran.dg/constant_shape.f90: New test case. -- If you're walking down the right path and you're willing to keep walking, eventually you'll make progress. Barack Obama
