From 07b575d5860dbc8791dbb9d10af9f918f34d7ff0 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Sat, 27 Jan 2024 17:41:43 +0100
Subject: [PATCH] Fortran: fix bounds-checking errors for CLASS array dummies
 [PR104908]

Commit r11-1235 addressed issues with bounds of unlimited polymorphic array
dummies.  However, using the descriptor from sym->backend_decl does break
the case of CLASS array dummies.  The obvious solution is to restrict the
fix to the unlimited polymorphic case, thus keeping the original descriptor
in the ordinary case.

gcc/fortran/ChangeLog:

	PR fortran/104908
	* trans-array.c (gfc_conv_array_ref): Restrict use of transformed
	descriptor (sym->backend_decl) to the unlimited polymorphic case.

gcc/testsuite/ChangeLog:

	PR fortran/104908
	* gfortran.dg/pr104908.f90: New test.

(cherry picked from commit ce61de1b8a1bb3a22118e900376f380768f2ba59)
---
 gcc/fortran/trans-array.c              |  5 +++-
 gcc/testsuite/gfortran.dg/pr104908.f90 | 32 ++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/pr104908.f90

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index abdecc7df7a9..44f6ad7c8a00 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -3723,7 +3723,10 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar, gfc_expr *expr,
     }
 
   decl = se->expr;
-  if (IS_CLASS_ARRAY (sym) && sym->attr.dummy && ar->as->type != AS_DEFERRED)
+  if (UNLIMITED_POLY(sym)
+      && IS_CLASS_ARRAY (sym)
+      && sym->attr.dummy
+      && ar->as->type != AS_DEFERRED)
     decl = sym->backend_decl;
 
   cst_offset = offset = gfc_index_zero_node;
diff --git a/gcc/testsuite/gfortran.dg/pr104908.f90 b/gcc/testsuite/gfortran.dg/pr104908.f90
new file mode 100644
index 000000000000..c3a30b0003c5
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr104908.f90
@@ -0,0 +1,32 @@
+! { dg-do compile }
+! { dg-additional-options "-fcheck=bounds -fdump-tree-original" }
+!
+! PR fortran/104908 - incorrect out-of-bounds runtime error
+
+program test
+  implicit none
+  type vec
+     integer :: x(3) = [2,4,6]
+  end type vec
+  type(vec) :: w(2)
+  call sub(w)
+contains
+  subroutine sub (v)
+    class(vec), intent(in) :: v(:)
+    integer :: k, q(3)
+    q = [ (v(1)%x(k), k = 1, 3) ]   ! <-- was failing here after r11-1235
+    print *, q
+  end
+end
+
+subroutine sub2 (zz)
+  implicit none
+  type vec
+     integer :: x(2,1)
+  end type vec
+  class(vec), intent(in) :: zz(:)   ! used to ICE after r11-1235
+  integer :: k
+  k = zz(1)%x(2,1)
+end
+
+! { dg-final { scan-tree-dump-times " above upper bound " 4 "original" } }
-- 
2.47.2