Re: [Patch, fortran] PR97122 - Spurious FINAL ... must be in the specification part of a MODULE

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

On Tue, May 09, 2023 at 08:24:16PM +0200, Harald Anlauf wrote:
> Hi Paul,
> 
> On 5/9/23 17:51, Paul Richard Thomas via Gcc-patches wrote:
> > Hi All,
> > 
> > Thanks to Steve Kargl for the fix. It caused finalize_8.f03 to fail because
> > this testcase checked that finalizable derived types could not be specified
> > in a submodule. I have replaced the original test with a test of the patch.
> > 
> > Thanks also to Malcolm Cohen for guidance on this.
> > 
> > OK for trunk?
> 
> the patch looks good to me.  However:
> 
> @@ -11637,8 +11637,9 @@ gfc_match_final_decl (void)
>    block = gfc_state_stack->previous->sym;
             ^^^^^^^^^^^^^^^^^^^^^^^^^
See below.

>    gcc_assert (block);
> 
> -  if (!gfc_state_stack->previous || !gfc_state_stack->previous->previous
> -      || gfc_state_stack->previous->previous->state != COMP_MODULE)
> +  if (gfc_state_stack->previous->previous
> +      && gfc_state_stack->previous->previous->state != COMP_MODULE
> +      && gfc_state_stack->previous->previous->state != COMP_SUBMODULE)
>      {
>        gfc_error ("Derived type declaration with FINAL at %C must be in
> the"
>                  " specification part of a MODULE");
> 
> I am wondering if we should keep the protection against a potential
> NULL pointer dereference (i.e. gfc_state_stack->previous == NULL) for
> possibly invalid code.  I have failed to produce a simple testcase,
> but others may have "better" ideas.

It's not needed.  See above.  gfc_state_stack->previous is referenced
a few lines above the if-stmt.  The reference will segfault if the
pointer is NULL.

-- 
Steve