[Patch] Fortran: Fix absent-optional handling for nondescriptor arrays (PR94672)

[Patch] Fortran: Fix absent-optional handling for nondescriptor arrays (PR94672)

[Tobias Burnus]

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This fixes an issue caused by the patch for PR 94672, which
affects both GCC 10 and GCC 11.

Only 'sVal' of 'subroutine foo' was affected, the rest is
only a crosscheck that it worked for those code paths.

(I did check against the dump – which looks fine. I could
add dump tests as well. The 'foo' test was failing with
'stop 5' (absent argument) at runtime before the patch;
the report was for the 'stop 4' case, which is probably
harder to trigger as run-time fail as the stack memory
is likely zero-initialized. → -fdump-tree-original scan
test useful?)

OK for mainline and GCC 10?

Tobias

-----------------
Mentor Graphics (Deutschland) GmbH, Arnulfstraße 201, 80634 München / Germany
Registergericht München HRB 106955, Geschäftsführer: Thomas Heurung, Alexander Walter

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Fortran: Fix absent-optional handling for nondescriptor arrays (PR94672)

gcc/fortran/ChangeLog:

	PR fortran/94672
	* trans-array.c (gfc_trans_g77_array): Check against the parm decl and
	set the nonparm decl used for the is-present check to NULL if absent.

gcc/testsuite/ChangeLog:

	PR fortran/94672
	* gfortran.dg/optional_assumed_charlen_2.f90: New test.

 gcc/fortran/trans-array.c                          | 10 ++++-
 .../gfortran.dg/optional_assumed_charlen_2.f90     | 48 ++++++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 0e3495d59cc..6566c47d4ae 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -6472,8 +6472,14 @@ gfc_trans_g77_array (gfc_symbol * sym, gfc_wrapped_block * block)
 
   if (sym->attr.optional || sym->attr.not_always_present)
     {
-      tmp = gfc_conv_expr_present (sym);
-      stmt = build3_v (COND_EXPR, tmp, stmt, build_empty_stmt (input_location));
+      tree nullify;
+      if (TREE_CODE (parm) != PARM_DECL)
+	nullify = fold_build2_loc (input_location, MODIFY_EXPR, void_type_node,
+				   parm, null_pointer_node);
+      else
+	nullify = build_empty_stmt (input_location);
+      tmp = gfc_conv_expr_present (sym, true);
+      stmt = build3_v (COND_EXPR, tmp, stmt, nullify);
     }
 
   gfc_add_init_cleanup (block, stmt, NULL_TREE);
diff --git a/gcc/testsuite/gfortran.dg/optional_assumed_charlen_2.f90 b/gcc/testsuite/gfortran.dg/optional_assumed_charlen_2.f90
new file mode 100644
index 00000000000..fa8cfd79038
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/optional_assumed_charlen_2.f90
@@ -0,0 +1,48 @@
+! { dg-do run }
+! PR fortran/94672
+!
+! Contributed by Tomáš Trnka
+!
+module m
+  implicit none (type,external)
+  type t
+    integer :: i = 5
+  end type t
+contains
+subroutine bar(x, y, z, n)
+  integer, value :: n
+  type(t), intent(out), optional :: x(:), y(n), z(:)
+  allocatable :: z
+end subroutine bar
+
+subroutine foo (n, nFound, sVal)
+   integer,                   value  :: n
+   integer,                   intent(out)  :: nFound
+   character(*),    optional, intent(out) :: sVal(n)
+
+   nFound = 0
+
+   if (present(sVal)) then
+      nFound = nFound + 1
+   end if
+end subroutine
+end
+
+use m
+implicit none (type,external)
+type(t) :: a(7), b(7), c(:)
+allocatable :: c
+integer :: nn, nf
+character(len=4) :: str
+
+allocate(c(7))
+call bar(a,b,c,7)
+if (any(a(:)%i /= 5)) stop 1
+if (any(b(:)%i /= 5)) stop 2
+if (allocated(c)) stop 3
+
+call foo(7, nf, str)
+if (nf /= 1) stop 4
+call foo(7, nf)
+if (nf /= 0) stop 5
+end

Re: [Patch] Fortran: Fix absent-optional handling for nondescriptor arrays (PR94672)

[Andre Vehreschild]

Hi Tobias,

the patch looks ok to me.

Thanks for the patch.

Regards,
	Andre

On Wed, 26 Aug 2020 18:29:40 +0200
Tobias Burnus <tobias@codesourcery.com> wrote:

> This fixes an issue caused by the patch for PR 94672, which
> affects both GCC 10 and GCC 11.
> 
> Only 'sVal' of 'subroutine foo' was affected, the rest is
> only a crosscheck that it worked for those code paths.
> 
> (I did check against the dump – which looks fine. I could
> add dump tests as well. The 'foo' test was failing with
> 'stop 5' (absent argument) at runtime before the patch;
> the report was for the 'stop 4' case, which is probably
> harder to trigger as run-time fail as the stack memory
> is likely zero-initialized. → -fdump-tree-original scan
> test useful?)
> 
> OK for mainline and GCC 10?
> 
> Tobias
> 
> -----------------
> Mentor Graphics (Deutschland) GmbH, Arnulfstraße 201, 80634 München / Germany
> Registergericht München HRB 106955, Geschäftsführer: Thomas Heurung,
> Alexander Walter


-- 
Andre Vehreschild * Email: vehre ad gmx dot de