Re: [PATCH] openmp, fortran: Check that event handles passed to detach clauses are not arrays [PR104131]

[Mikael Morin <morin-mikael@orange.fr>]

Le 28/02/2022 à 17:00, Jakub Jelinek a écrit :
> On Mon, Feb 28, 2022 at 04:54:24PM +0100, Mikael Morin wrote:
>> Le 28/02/2022 à 15:27, Kwok Cheung Yeung a écrit :
>>> On 28/02/2022 2:07 pm, Jakub Jelinek wrote:
>> (...)
>>>> Don't we usually test instead || (*expr)->rank != 0 when testing for
>>>> scalars?
>>>>
>> (...)
>>>
>>> So (*expr)->rank is 0 here even with an array. I'm not sure why - is
>>> rank updated later, or did we forget to call something on the event
>>> handle expression?
>>>
>>> Testing against n->sym->as for an array check has been used elsewhere in
>>> openmp.cc, to prevent reductions against arrays in OpenACC in
>>> resolve_omp_clauses.
>>>
>> I can’t tell what openmp requires; it depends on your needs.
>>
>> Checking sym->as captures array variables which may include scalar
>> expressions (arr(10) is a scalar expression even if arr is an array
>> variable), while checking expr->rank only capture array expression,
>> including scalar variable with array subcomponent (scal%array_comp(:) is an
>> array expression, even if scal is a scalar variable).
>>
>> gfc_resolve_expr, through gfc_expression_rank takes care of properly setting
>> expr->rank.
>> If the check is done at resolution stage (somewhere in resolve_omp_clauses I
>> guess?), the rank should be set.
>>
>> I hope it helps.
> 
> It is true that the spots I saw in fortran/openmp.cc that test rank look
> like:
>          if (!gfc_resolve_expr (el->expr)
>              || el->expr->ts.type != BT_INTEGER || el->expr->rank != 0)
> etc., so probably !gfc_resolve_expr call is missing.
> 
As long as the expression is expected to not be a (contained) function 
call, I think it should work.

In the general case non-syntaxic errors are preferably checked and 
reported later at resolution stage, where contained functions are known.