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

[Harald Anlauf <anlauf@gmx.de>]

On 5/9/23 20:29, Steve Kargl via Gcc-patches wrote:
> 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.
>

You're absolutely right.  So it is OK as is.