[Patch, fortran] PR104272 - finalizer gets called during allocate

[Paul Richard Thomas]

Hi Harald,

Quite right - good spot. There was an 'else' that turned out to be
unnecessary.

Thanks

Paul


On Wed, 5 Apr 2023 at 19:50, Harald Anlauf <anlauf@gmx.de> wrote:

> Hi Paul,
>
> On 4/5/23 08:53, Paul Richard Thomas via Gcc-patches wrote:
> > Hi All,
> >
> > This is a first in my recent experience - a very old bug that produces
> too
> > many finalizations! It results from a bit of a fix up, where class
> objects
> > are allocated using the derived typespec, rather than a source or mold
> > expression. This occurs upstream in resolve.cc, where the default
> > initializer is assigned to expr3 but no means are provided to identify
> what
> > it is. The patch applies a signaling bit-field to the ext field of
> > gfc_code, which then suppresses the deallocation of allocatable
> components
> > in the allocate expression. I have checked that this does not cause
> memory
> > leaks, even though the number of builtin_frees in class_result_8.f90 goes
> > down by one.
>
> can you have a look again at the logic in the hunk touching
> trans-stmt.cc (gfc_trans_allocate)?  I haven't checked in detail,
> but it seems possible that you get a stale tmp in the
> gfc_prepend_expr_to_block if (code->ext.alloc.expr3_not_explicit == 0).
> Wouldn't it make more sense to move this condition before the braces
> as part of the overall condition?
>
> > OK for mainline?
>
> Otherwise this LGTM.
>
> Thanks for the patch!
>
> Harald
>
> > Paul
> >
> > Fortran: Fix and excess finalization during allocation [PR104272]
> >
> > 2023-04-04  Paul Thomas  <pault@gcc.gnu.org>
> >
> > gcc/fortran
> > PR fortran/104272
> > * gfortran.h : Add expr3_not_explicit bit field to gfc_code.
> > * resolve.cc (resolve_allocate_expr): Set bit field when the
> > default initializer is applied to expr3.
> > * trans-stmt.cc (gfc_trans_allocate): If expr3_not_explicit is
> > set, do not deallocate expr3.
> >
> > gcc/testsuite/
> > PR fortran/104272
> > * gfortran.dg/class_result_8.f90 : Number of builtin_frees down
> > from 6 to 5 without memory leaks.
> > * gfortran.dg/finalize_52.f90: New test
>
>

-- 
"If you can't explain it simply, you don't understand it well enough" -
Albert Einstein