Re: [PATCH] Fix Bug 109512 - accepts implicit dummy procedure even with "implicit none (external)"

> Am 17.01.2026 um 03:31 schrieb Jerry D <[email protected]>:
> 
> On 1/16/26 2:21 PM, Jerry D wrote:
>> The following fix provided by Steve.
>> Fairly self explanatory.
>> Regression tested x86_64-linux.
>> OK for mainline? Copied release manager as we are in Stage 4.
>> Regards,
> 
> Updated the patch per Steve to include a check for functions as well as subroutines.
> 
> Regression tested again. OK for mainline.

Ok from RM perspective.  Fortran isn’t release critical apart from build issues.

Richard 

>    Fortran: Fix accepts invalid implicit none (external)
> 
>    This patch yields an error for the test case which was
>    previously being accepted even though implicit none (external)
>    was being specified.
> 
>            PR fortran/109512
> 
>    gcc/fortran/ChangeLog:
> 
>            * resolve.cc (resolve_function): Check if an external
>            attribute is required on a call to an external procedure.
>            (resolve_call): Likewise.
> 
>    gcc/testsuite/ChangeLog:
> 
>            * gfortran.dg/pr109512.f90: New test.
> 
> diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
> index be72132c79d..0c52511790f 100644
> --- a/gcc/fortran/resolve.cc
> +++ b/gcc/fortran/resolve.cc
> @@ -3687,6 +3687,20 @@ resolve_function (gfc_expr *expr)
>     gfc_warning (OPT_Wdeprecated_declarations,
>         "Using function %qs at %L is deprecated",
>         sym->name, &expr->where);
> +
> +  /* Check an external function supplied as a dummy argument has an external
> +     attribute when a program unit uses 'implicit none (external)'.  */
> +  if (expr->expr_type == EXPR_FUNCTION
> +      && expr->symtree
> +      && expr->symtree->n.sym->attr.dummy
> +      && expr->symtree->n.sym->ns->has_implicit_none_export
> +      && !gfc_is_intrinsic(expr->symtree->n.sym, 0, expr->where))
> +    {
> +      gfc_error ("Dummy procedure %qs at %L requires an EXTERNAL attribute",
> +         sym->name, &expr->where);
> +      return false;
> +    }
> +
>   return t;
> }
> 
> @@ -4167,6 +4181,16 @@ resolve_call (gfc_code *c)
>   /* Resume assumed_size checking.  */
>   need_full_assumed_size--;
> 
> +  /* If 'implicit none (external)' and the symbol is a dummy argument,
> +     check for an 'external' attribute.  */
> +  if (csym->ns->has_implicit_none_export
> +      && csym->attr.external == 0 && csym->attr.dummy == 1)
> +    {
> +      gfc_error ("Dummy procedure %qs at %L requires an EXTERNAL attribute",
> +         csym->name, &c->loc);
> +      return false;
> +    }
> +
>   /* If external, check for usage.  */
>   if (csym && is_external_proc (csym))
>     resolve_global_procedure (csym, &c->loc, 1);
> diff --git a/gcc/testsuite/gfortran.dg/pr109512.f90 b/gcc/testsuite/gfortran.dg/pr109512.f90
> new file mode 100644
> index 00000000000..b9984cad107
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/pr109512.f90
> @@ -0,0 +1,10 @@
> +! { dg-do compile }
> +subroutine foo(bar)
> +  implicit none (external)
> +  call bar(1)  ! { dg-error "requires an EXTERNAL attribute" }
> +end subroutine foo
> +
> +function bah(bar)
> +  implicit none (external)
> +  foo = bar(1)        ! { dg-error "requires an EXTERNAL attribute" }
> +end function bah
> 
>