Re: [PATCH] PR fortran/78033 -- This was a REAL pain

[Paul Richard Thomas <paul dot richard dot thomas at gmail dot com>]

Hi Steve,

Thanks for persevering with this. The patch looks good to me. If it
has regtested OK, please feel free to commit.

Cheers

Paul

On 22 October 2016 at 02:22, Steve Kargl
<sgk@troutmask.apl.washington.edu> wrote:
> All,
>
> The attached patch fixes PR fortran/78033.  This was a REAL pain
> to fix because Fortran overloads REAL as an intrinsic type and
> an intrinsic subprogram.
>
> gfc_match_type_spec() in match.c is used to match Fortran 2003
> type-specs in things like array constructors and TYPE IS statements.
> At some point in time, PR fortran/54730 was submitted because an ICE
> occurred for
>
>   subroutine s
>     implicit none
>     intrinsic :: real
>     real :: vec(1:2)
>     vec = (/ real(a = 1), 1. /)
>   end subroutine s
>
> where a symbol for 'a' was create while parsing for a validate
> typespec.  The invalid 'a' was causing an ICE during translation.
> Mikael fixed the ICE by introducing checkpointing of the symbols in
> gfc_match_array_constructor() in array.c, which allowed 'a' to be
> removed.
>
> Fast-forward to PR fortran/78033, submitted a few days ago.
> Code like
>
>   subroutine f(n, x)
>      integer, intent(in) :: n
>      complex, intent(in) :: x(1:n)
>      real :: y(2*n)
>      y = [real(x(1:n), aimag(x(1:n))]
>   end subroutine f
>
> was now ICE'ing due what appears to be a tangling checkpoint.
>
> f951: internal compiler error: in enforce_single_undo_checkpoint,
> at fortran/symbol.c:3514
>
> If I disabled, Mikael's fix for PR fortran/54730 then PR fortran/78033
> would compile with the expected regression with PR fortran/54730.  Having
> spent to much time looking for a mismatch in checkpoints, I decided to
> remove Mikael's fix in gfc_match_array_constructor() and fix the issue
> in gfc_match_type_spec() where I special case the parsing of
> REAL([KIND]=scalar-int-initialization-expr).
>
> An early version of the patch passed regression except for gomp/udr3.f90.
> Note that gfortran never vists gfc_match_type_spec while compling udr3.f90.
> I've deleted obj/ and started a clean bootstrap to see if this failure
> was collateral damage for my tinkering.  If regression testing is
> successfull, OK to commit?
>
> 2016-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/78033
>         * array.c (gfc_match_array_constructor): Remove checkpointing
>         introduced in r196416.  Move initialization to top of function.
>         * match.c (gfc_match_type_spec): Special case matching for REAL.
>
> 2016-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/78033
>         * gfortran.dg/pr78033.f90: New test.
>
> --
> Steve



-- 
The difference between genius and stupidity is; genius has its limits.

Albert Einstein