[Bug fortran/41936] Memory leakage with allocatables and user-defined operators

["dominiq at lps dot ens.fr" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41936

--- Comment #3 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Fixed if one adds the code below (copied from gfc_conv_array_parameter).
> I'm afraid this could change a memory leak into a double free (see PR 40850).
> Also, not quite right (even if the middle-end optimizers are likely to fix it) 
> because it adds cleanup code to both foo and bar.

With the patch in comment 2, the tests gfortran.dg/alloc_comp_basics_1.f90 and
gfortran.dg/alloc_comp_constructor_1.f90 fail because there are 21 occurrences
of "builtin_free". This is fixed by the following updated patch (against
r209838)

--- ../_clean/gcc/fortran/trans-expr.c    2014-04-25 14:30:23.000000000 +0200
+++ gcc/fortran/trans-expr.c    2014-04-27 16:03:28.000000000 +0200
@@ -6474,6 +6474,19 @@ gfc_conv_expr_reference (gfc_se * se, gf

   /* Take the address of that value.  */
   se->expr = gfc_build_addr_expr (NULL_TREE, var);
+  if ((expr->ts.type == BT_DERIVED || expr->ts.type == BT_CLASS)
+      && expr->ts.u.derived->attr.alloc_comp && expr->rank
+      && expr->expr_type != EXPR_VARIABLE)
+    {
+      tree tmp;
+
+      tmp = build_fold_indirect_ref_loc (input_location, se->expr);
+      tmp = gfc_deallocate_alloc_comp (expr->ts.u.derived, tmp, expr->rank);
+      
+      /* The components shall be deallocated before
+         their containing entity.  */
+      gfc_prepend_expr_to_block (&se->post, tmp);
+    }
 }