diff mbox series

[fortran] PR64290 - [F03] No finalization at deallocation of LHS

Message ID CAGkQGi+r=sshyVV5BiR9qTd1EKOcadHydS3Vc_ZHc3VDg2p5aQ@mail.gmail.com
State New
Headers show
Series [fortran] PR64290 - [F03] No finalization at deallocation of LHS | expand

Commit Message

Paul Richard Thomas Jan. 17, 2022, 11:57 a.m. UTC
Hi All,

Strictly speaking, the attached patch is branching out into a more
generalised attack on PR37336(Finalization) - [F03] Finish derived-type
finalization but most of it fixes PR64290.

I started work on this patch almost a year ago but had to drop it due
daytime work pressure and only picked it up again a couple of weeks back.
It is not, as yet, complete but I thought to post it in its present form
because stage 3 ended yesterday.

The main thrusts of the patch are:

(i) To correct the order taken by finalization and deallocation of
components for the lhs of assignments. This is done instead by a call to
Tobias' finalization wrapper, rather than performing finalization component
by component in structure_alloc_comps;

(ii) To add finalization of scalar derived type function results, again by
use of the finalization wrapper. This points to a problem that I haven't
yet managed to fix, F2018(7.5.6.3 para 5) "If an executable construct
references a nonpointer function, the result is finalized after execution
of the innermost executable construct containing the reference." I have
been struggling to avoid implementing this by introducing a finalization
block into gfc_se but have run out of ideas as to how to do it otherwise.
(eg. Try using a finalizable function as the actual argument of another
procedure.); and

(iii) Once (ii) is added, a segfault occurs if the derived type has
allocatable, finalizable components. (PR96122) This occurred because the
call to the component finalization wrapper was missing two arguments in the
call; most particularly 'byte_stride'.

There is still quite a lot to do to bring together common code chunks, fix
the ordering requirement of F2018 (7.5.6.3 para 5), add more testcases.
It's certainly not ready to be committed yet :-(

Regards

Paul

Fortran:Implement missing finalization features [PR64290]

2022-01-17  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
PR fortran/103854
* class.c (has_finalizer_component): Do not return true for
procedure pointer components.

PR fortran/96087
* class.c (finalize_component): Include the missing arguments
in the call to the component's finalizer wrapper.

PR fortran/64290
* resolve.c (resolve_where, gfc_resolve_where_code_in_forall,
gfc_resolve_forall_body, gfc_resolve_code): Check that the op
code is still EXEC_ASSIGN. If it is set lhs to must finalize.
* trans-array.c (structure_alloc_comps): Add boolean argument
to suppress finalization and use it for calls from
gfc_deallocate_alloc_comp_no_caf. Otherwise it defaults to
false.
(gfc_alloc_allocatable_for_assignment): Suppress finalization
by setting new arg in call to gfc_deallocate_alloc_comp_no_caf.
* trans-array.h : Add the new boolean argument to the prototype
of gfc_deallocate_alloc_comp_no_caf with a default of false.
* trans-expr.c (gfc_conv_procedure_call): Call finalizer for
finalizable scalar function results.
(gfc_trans_scalar_assign): Suppress finalization by setting new
argument in call to gfc_deallocate_alloc_comp_no_caf.
(gfc_assignment_finalizer_call): New function to provide
finalization on intrinsic assignment.
(trans_class_assignment, gfc_trans_assignment_1): Call it and
add the block between the rhs evaluation and any reallocation
on assignment that there might be.

gcc/testsuite/
PR fortran/64290
* gfortran.dg/finalize_38.f90 : New test.
* gfortran.dg/allocate_with_source_25.f90 : The number of final
calls goes down from 6 to 4.
diff mbox series

Patch

diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c
index 2cb0c6572bd..18289eaffe8 100644
--- a/gcc/fortran/class.c
+++ b/gcc/fortran/class.c
@@ -896,7 +896,8 @@  has_finalizer_component (gfc_symbol *derived)
    gfc_component *c;
 
   for (c = derived->components; c; c = c->next)
-    if (c->ts.type == BT_DERIVED && !c->attr.pointer && !c->attr.allocatable)
+    if (c->ts.type == BT_DERIVED && !c->attr.pointer && !c->attr.allocatable
+	&& c->attr.flavor != FL_PROCEDURE)
       {
 	if (c->ts.u.derived->f2k_derived
 	    && c->ts.u.derived->f2k_derived->finalizers)
@@ -1059,7 +1060,8 @@  finalize_component (gfc_expr *expr, gfc_symbol *derived, gfc_component *comp,
     {
       /* Call FINAL_WRAPPER (comp);  */
       gfc_code *final_wrap;
-      gfc_symbol *vtab;
+      gfc_symbol *vtab, *byte_stride;
+      gfc_expr *scalar, *size_expr, *fini_coarray_expr;
       gfc_component *c;
 
       vtab = gfc_find_derived_vtab (comp->ts.u.derived);
@@ -1068,12 +1070,54 @@  finalize_component (gfc_expr *expr, gfc_symbol *derived, gfc_component *comp,
 	  break;
 
       gcc_assert (c);
+
+      /* Set scalar argument for storage_size.  */
+      gfc_get_symbol ("comp_byte_stride", sub_ns, &byte_stride);
+      byte_stride->ts = e->ts;
+      byte_stride->attr.flavor = FL_VARIABLE;
+      byte_stride->attr.value = 1;
+      byte_stride->attr.artificial = 1;
+      gfc_set_sym_referenced (byte_stride);
+      gfc_commit_symbol (byte_stride);
+      scalar = gfc_lval_expr_from_sym (byte_stride);
+
       final_wrap = gfc_get_code (EXEC_CALL);
       final_wrap->symtree = c->initializer->symtree;
       final_wrap->resolved_sym = c->initializer->symtree->n.sym;
       final_wrap->ext.actual = gfc_get_actual_arglist ();
       final_wrap->ext.actual->expr = e;
 
+      /* size_expr = STORAGE_SIZE (...) / NUMERIC_STORAGE_SIZE.  */
+      size_expr = gfc_get_expr ();
+      size_expr->where = gfc_current_locus;
+      size_expr->expr_type = EXPR_OP;
+      size_expr->value.op.op = INTRINSIC_DIVIDE;
+
+      /* STORAGE_SIZE (array,kind=c_intptr_t).  */
+      size_expr->value.op.op1
+	= gfc_build_intrinsic_call (sub_ns, GFC_ISYM_STORAGE_SIZE,
+				    "storage_size", gfc_current_locus, 2,
+				    scalar,
+				    gfc_get_int_expr (gfc_index_integer_kind,
+						      NULL, 0));
+
+      /* NUMERIC_STORAGE_SIZE.  */
+      size_expr->value.op.op2 = gfc_get_int_expr (gfc_index_integer_kind, NULL,
+						  gfc_character_storage_size);
+      size_expr->value.op.op1->ts = size_expr->value.op.op2->ts;
+      size_expr->ts = size_expr->value.op.op1->ts;
+
+      /* Which provides the argument 'byte_stride'.....  */
+      final_wrap->ext.actual->next = gfc_get_actual_arglist ();
+      final_wrap->ext.actual->next->expr = size_expr;
+
+      /* ...and last of all the 'fini_coarray' argument.  */
+      fini_coarray_expr = gfc_lval_expr_from_sym (fini_coarray);
+      final_wrap->ext.actual->next->next = gfc_get_actual_arglist ();
+      final_wrap->ext.actual->next->next->expr = fini_coarray_expr;
+
+
+
       if (*code)
 	{
 	  (*code)->next = final_wrap;
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 43eeefee07f..e4b60a44a59 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -10512,6 +10512,10 @@  resolve_where (gfc_code *code, gfc_expr *mask)
 	      if (e && !resolve_where_shape (cnext->expr1, e))
 	       gfc_error ("WHERE assignment target at %L has "
 			  "inconsistent shape", &cnext->expr1->where);
+
+	      if (cnext->op == EXEC_ASSIGN)
+		cnext->expr1->must_finalize = 1;
+
 	      break;
 
 
@@ -10599,6 +10603,10 @@  gfc_resolve_where_code_in_forall (gfc_code *code, int nvar,
 	    /* WHERE assignment statement */
 	    case EXEC_ASSIGN:
 	      gfc_resolve_assign_in_forall (cnext, nvar, var_expr);
+
+	      if (cnext->op == EXEC_ASSIGN)
+		cnext->expr1->must_finalize = 1;
+
 	      break;
 
 	    /* WHERE operator assignment statement */
@@ -10645,6 +10653,10 @@  gfc_resolve_forall_body (gfc_code *code, int nvar, gfc_expr **var_expr)
 	case EXEC_ASSIGN:
 	case EXEC_POINTER_ASSIGN:
 	  gfc_resolve_assign_in_forall (c, nvar, var_expr);
+
+	  if (c->op == EXEC_ASSIGN)
+	    c->expr1->must_finalize = 1;
+
 	  break;
 
 	case EXEC_ASSIGN_CALL:
@@ -12069,6 +12081,9 @@  start:
 	      && code->expr1->ts.u.derived->attr.defined_assign_comp)
 	    generate_component_assignments (&code, ns);
 
+	  if (code->op == EXEC_ASSIGN)
+	    code->expr1->must_finalize = 1;
+
 	  break;
 
 	case EXEC_LABEL_ASSIGN:
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index a77f3318846..e06b8ba4eb2 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -994,9 +994,9 @@  gfc_get_array_span (tree desc, gfc_expr *expr)
       if (tmp && TREE_CODE (tmp) == ARRAY_TYPE && TYPE_STRING_FLAG (tmp))
 	{
 	  gcc_assert (expr->ts.type == BT_CHARACTER);
-	  
+
 	  tmp = gfc_get_character_len_in_bytes (tmp);
-	  
+
 	  if (tmp == NULL_TREE || integer_zerop (tmp))
 	    {
 	      tree bs;
@@ -1007,7 +1007,7 @@  gfc_get_array_span (tree desc, gfc_expr *expr)
 	      tmp = fold_build2_loc (input_location, MULT_EXPR,
 				     gfc_array_index_type, tmp, bs);
 	    }
-	  
+
 	  tmp = (tmp && !integer_zerop (tmp))
 	    ? (fold_convert (gfc_array_index_type, tmp)) : (NULL_TREE);
 	}
@@ -5657,7 +5657,12 @@  gfc_array_init_size (tree descriptor, int rank, int corank, tree * poffset,
   gfc_se se;
   int n;
 
-  type = TREE_TYPE (descriptor);
+  if (expr->ts.type == BT_CLASS
+      && expr3_desc != NULL_TREE
+      && GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (expr3_desc)))
+    type = TREE_TYPE (expr3_desc);
+  else
+    type = TREE_TYPE (descriptor);
 
   stride = gfc_index_one_node;
   offset = gfc_index_zero_node;
@@ -7478,7 +7483,7 @@  gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
 
   if (!se->direct_byref)
     se->unlimited_polymorphic = UNLIMITED_POLY (expr);
-  
+
   /* Special case things we know we can pass easily.  */
   switch (expr->expr_type)
     {
@@ -8922,7 +8927,7 @@  static gfc_actual_arglist *pdt_param_list;
 static tree
 structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		       tree dest, int rank, int purpose, int caf_mode,
-		       gfc_co_subroutines_args *args)
+		       gfc_co_subroutines_args *args, bool no_finalization)
 {
   gfc_component *c;
   gfc_loopinfo loop;
@@ -9010,11 +9015,12 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 					     gfc_conv_array_data (dest));
 	  dref = gfc_build_array_ref (tmp, index, NULL);
 	  tmp = structure_alloc_comps (der_type, vref, dref, rank,
-				       COPY_ALLOC_COMP, caf_mode, args);
+				       COPY_ALLOC_COMP, caf_mode, args,
+				       no_finalization);
 	}
       else
 	tmp = structure_alloc_comps (der_type, vref, NULL_TREE, rank, purpose,
-				     caf_mode, args);
+				     caf_mode, args, no_finalization);
 
       gfc_add_expr_to_block (&loopbody, tmp);
 
@@ -9048,13 +9054,15 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
   if (purpose == DEALLOCATE_ALLOC_COMP && der_type->attr.pdt_type)
     {
       tmp = structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-				   DEALLOCATE_PDT_COMP, 0, args);
+				   DEALLOCATE_PDT_COMP, 0, args,
+				   no_finalization);
       gfc_add_expr_to_block (&fnblock, tmp);
     }
   else if (purpose == ALLOCATE_PDT_COMP && der_type->attr.alloc_comp)
     {
       tmp = structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-				   NULLIFY_ALLOC_COMP, 0, args);
+				   NULLIFY_ALLOC_COMP, 0, args,
+				   no_finalization);
       gfc_add_expr_to_block (&fnblock, tmp);
     }
 
@@ -9112,7 +9120,7 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		  add_when_allocated
 		      = structure_alloc_comps (CLASS_DATA (c)->ts.u.derived,
 					       comp, NULL_TREE, rank, purpose,
-					       caf_mode, args);
+					       caf_mode, args, no_finalization);
 		}
 	      else
 		{
@@ -9120,7 +9128,8 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		  add_when_allocated = structure_alloc_comps (c->ts.u.derived,
 							      comp, NULL_TREE,
 							      rank, purpose,
-							      caf_mode, args);
+							      caf_mode, args,
+							      no_finalization);
 		}
 	    }
 
@@ -9216,8 +9225,8 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		continue;
 	    }
 
-	  if ((c->ts.type == BT_DERIVED && !c->attr.pointer)
-	     || (c->ts.type == BT_CLASS && !CLASS_DATA (c)->attr.class_pointer))
+	  if (!no_finalization && ((c->ts.type == BT_DERIVED && !c->attr.pointer)
+	     || (c->ts.type == BT_CLASS && !CLASS_DATA (c)->attr.class_pointer)))
 	    /* Call the finalizer, which will free the memory and nullify the
 	       pointer of an array.  */
 	    deallocate_called = gfc_add_comp_finalizer_call (&tmpblock, comp, c,
@@ -9245,7 +9254,7 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		  add_when_allocated
 		      = structure_alloc_comps (CLASS_DATA (c)->ts.u.derived,
 					       comp, NULL_TREE, rank, purpose,
-					       caf_mode, args);
+					       caf_mode, args, no_finalization);
 		}
 	      else
 		{
@@ -9253,7 +9262,8 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		  add_when_allocated = structure_alloc_comps (c->ts.u.derived,
 							      comp, NULL_TREE,
 							      rank, purpose,
-							      caf_mode, args);
+							      caf_mode, args,
+							      no_finalization);
 		}
 	    }
 
@@ -9551,7 +9561,8 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 				      decl, cdecl, NULL_TREE);
 	      rank = c->as ? c->as->rank : 0;
 	      tmp = structure_alloc_comps (c->ts.u.derived, comp, NULL_TREE,
-					   rank, purpose, caf_mode, args);
+					   rank, purpose, caf_mode, args,
+					   no_finalization);
 	      gfc_add_expr_to_block (&fnblock, tmp);
 	    }
 	  break;
@@ -9587,7 +9598,7 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 		  tmp = structure_alloc_comps (c->ts.u.derived, comp, dcmp,
 					       rank, purpose, caf_mode
 					       | GFC_STRUCTURE_CAF_MODE_IN_COARRAY,
-					       args);
+					       args, no_finalization);
 		  gfc_add_expr_to_block (&fnblock, tmp);
 		}
 	    }
@@ -9695,7 +9706,8 @@  structure_alloc_comps (gfc_symbol * der_type, tree decl,
 	      add_when_allocated = structure_alloc_comps (c->ts.u.derived,
 							  comp, dcmp,
 							  rank, purpose,
-							  caf_mode, args);
+							  caf_mode, args,
+							  no_finalization);
 	    }
 	  else
 	    add_when_allocated = NULL_TREE;
@@ -10068,7 +10080,8 @@  gfc_nullify_alloc_comp (gfc_symbol * der_type, tree decl, int rank,
 {
   return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
 				NULLIFY_ALLOC_COMP,
-				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY | caf_mode, NULL);
+				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY | caf_mode,
+				NULL, false);
 }
 
 
@@ -10081,7 +10094,8 @@  gfc_deallocate_alloc_comp (gfc_symbol * der_type, tree decl, int rank,
 {
   return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
 				DEALLOCATE_ALLOC_COMP,
-				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY | caf_mode, NULL);
+				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY | caf_mode,
+				NULL, false);
 }
 
 tree
@@ -10119,7 +10133,8 @@  gfc_bcast_alloc_comp (gfc_symbol *derived, gfc_expr *expr, int rank,
 
   tmp = structure_alloc_comps (derived, array, NULL_TREE, rank,
 			       BCAST_ALLOC_COMP,
-  			       GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY, &args);
+  			       GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY,
+			       &args, false);
   return tmp;
 }
 
@@ -10129,10 +10144,12 @@  gfc_bcast_alloc_comp (gfc_symbol *derived, gfc_expr *expr, int rank,
    status of coarrays.  */
 
 tree
-gfc_deallocate_alloc_comp_no_caf (gfc_symbol * der_type, tree decl, int rank)
+gfc_deallocate_alloc_comp_no_caf (gfc_symbol * der_type, tree decl, int rank,
+				  bool no_finalization)
 {
   return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-				DEALLOCATE_ALLOC_COMP, 0, NULL);
+				DEALLOCATE_ALLOC_COMP, 0, NULL,
+				no_finalization);
 }
 
 
@@ -10140,7 +10157,8 @@  tree
 gfc_reassign_alloc_comp_caf (gfc_symbol *der_type, tree decl, tree dest)
 {
   return structure_alloc_comps (der_type, decl, dest, 0, REASSIGN_CAF_COMP,
-				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY, NULL);
+				GFC_STRUCTURE_CAF_MODE_ENABLE_COARRAY,
+				NULL, false);
 }
 
 
@@ -10152,7 +10170,7 @@  gfc_copy_alloc_comp (gfc_symbol * der_type, tree decl, tree dest, int rank,
 		     int caf_mode)
 {
   return structure_alloc_comps (der_type, decl, dest, rank, COPY_ALLOC_COMP,
-				caf_mode, NULL);
+				caf_mode, NULL, false);
 }
 
 
@@ -10163,7 +10181,7 @@  tree
 gfc_copy_only_alloc_comp (gfc_symbol * der_type, tree decl, tree dest, int rank)
 {
   return structure_alloc_comps (der_type, decl, dest, rank,
-				COPY_ONLY_ALLOC_COMP, 0, NULL);
+				COPY_ONLY_ALLOC_COMP, 0, NULL, false);
 }
 
 
@@ -10178,7 +10196,7 @@  gfc_allocate_pdt_comp (gfc_symbol * der_type, tree decl, int rank,
   gfc_actual_arglist *old_param_list = pdt_param_list;
   pdt_param_list = param_list;
   res = structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-			       ALLOCATE_PDT_COMP, 0, NULL);
+			       ALLOCATE_PDT_COMP, 0, NULL, false);
   pdt_param_list = old_param_list;
   return res;
 }
@@ -10190,7 +10208,7 @@  tree
 gfc_deallocate_pdt_comp (gfc_symbol * der_type, tree decl, int rank)
 {
   return structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-				DEALLOCATE_PDT_COMP, 0, NULL);
+				DEALLOCATE_PDT_COMP, 0, NULL, false);
 }
 
 
@@ -10205,7 +10223,7 @@  gfc_check_pdt_dummy (gfc_symbol * der_type, tree decl, int rank,
   gfc_actual_arglist *old_param_list = pdt_param_list;
   pdt_param_list = param_list;
   res = structure_alloc_comps (der_type, decl, NULL_TREE, rank,
-			       CHECK_PDT_DUMMY, 0, NULL);
+			       CHECK_PDT_DUMMY, 0, NULL, false);
   pdt_param_list = old_param_list;
   return res;
 }
@@ -10926,7 +10944,7 @@  gfc_alloc_allocatable_for_assignment (gfc_loopinfo *loop,
 	&& expr1->ts.u.derived->attr.alloc_comp)
     {
       tmp = gfc_deallocate_alloc_comp_no_caf (expr1->ts.u.derived, old_desc,
-					      expr1->rank);
+					      expr1->rank, true);
       gfc_add_expr_to_block (&realloc_block, tmp);
     }
 
diff --git a/gcc/fortran/trans-array.h b/gcc/fortran/trans-array.h
index 04fee617590..3aae4d2c4eb 100644
--- a/gcc/fortran/trans-array.h
+++ b/gcc/fortran/trans-array.h
@@ -56,7 +56,8 @@  tree gfc_nullify_alloc_comp (gfc_symbol *, tree, int, int cm = 0);
 tree gfc_deallocate_alloc_comp (gfc_symbol *, tree, int, int cm = 0);
 tree gfc_bcast_alloc_comp (gfc_symbol *, gfc_expr *, int, tree,
 			   tree, tree, tree);
-tree gfc_deallocate_alloc_comp_no_caf (gfc_symbol *, tree, int);
+tree gfc_deallocate_alloc_comp_no_caf (gfc_symbol *, tree, int,
+				       bool no_finalization = false);
 tree gfc_reassign_alloc_comp_caf (gfc_symbol *, tree, tree);
 
 tree gfc_copy_alloc_comp (gfc_symbol *, tree, tree, int, int);
diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index 2e15a7e874c..e666c41517b 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -7675,9 +7675,58 @@  gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
   /* Allocatable scalar function results must be freed and nullified
      after use. This necessitates the creation of a temporary to
      hold the result to prevent duplicate calls.  */
+  bool allocatable = comp ? comp->attr.allocatable
+			    && !comp->attr.dimension
+			  : sym->attr.allocatable
+			    && !sym->attr.dimension;
+  bool finalizable = comp ? comp->ts.type == BT_DERIVED
+			    && gfc_is_finalizable (comp->ts.u.derived, NULL)
+			  : sym->ts.type == BT_DERIVED
+			    && gfc_is_finalizable (sym->ts.u.derived, NULL);
+  if (!byref && finalizable)
+    {
+      tree vptr, final_fndecl, desc;
+      gfc_symbol *vtab;
+      gfc_se post_se;
+      tmp = gfc_create_var (TREE_TYPE (se->expr), NULL);
+      gfc_add_modify (&se->pre, tmp, se->expr);
+      se->expr = tmp;
+      tmp = gfc_evaluate_now (se->expr, &se->pre);
+      gfc_add_expr_to_block (&se->pre,
+			     gfc_copy_alloc_comp (comp ? comp->ts.u.derived
+						       : sym->ts.u.derived,
+						  se->expr, tmp, 0, 0));
+      vtab = comp ? gfc_find_derived_vtab (comp->ts.u.derived)
+		  : gfc_find_derived_vtab (sym->ts.u.derived);
+      if (vtab->backend_decl == NULL_TREE)
+	vptr = gfc_get_symbol_decl (vtab);
+      else
+	vptr = vtab->backend_decl;
+      vptr = gfc_build_addr_expr (NULL, vptr);
+
+      final_fndecl = gfc_vptr_final_get (vptr);
+      final_fndecl = build_fold_indirect_ref_loc (input_location,
+						  final_fndecl);
+      gfc_init_se (&post_se, NULL);
+      desc = gfc_conv_scalar_to_descriptor (&post_se, tmp,
+					    comp ? comp->attr
+						 : sym->attr);
+      gfc_add_expr_to_block (&post, gfc_finish_block (&post_se.pre));
+      desc = build_call_expr_loc (input_location,
+				  final_fndecl, 3,
+				  gfc_build_addr_expr (NULL, desc),
+				  gfc_vptr_size_get (vptr),
+				  boolean_false_node);
+      gfc_add_expr_to_block (&post, desc);
+      if (allocatable)
+	{
+	  tmp = gfc_call_free (tmp);
+	  gfc_add_expr_to_block (&post, tmp);
+	}
+    }
+
   if (!byref && sym->ts.type != BT_CHARACTER
-      && ((sym->attr.allocatable && !sym->attr.dimension && !comp)
-	  || (comp && comp->attr.allocatable && !comp->attr.dimension)))
+      && allocatable && !finalizable)
     {
       tmp = gfc_create_var (TREE_TYPE (se->expr), NULL);
       gfc_add_modify (&se->pre, tmp, se->expr);
@@ -10430,7 +10479,8 @@  gfc_trans_scalar_assign (gfc_se * lse, gfc_se * rse, gfc_typespec ts,
       if (dealloc)
 	{
 	  tmp_var = gfc_evaluate_now (lse->expr, &lse->pre);
-	  tmp = gfc_deallocate_alloc_comp_no_caf (ts.u.derived, tmp_var, 0);
+	  tmp = gfc_deallocate_alloc_comp_no_caf (ts.u.derived, tmp_var,
+						  0, true);
 	  if (deep_copy)
 	    tmp = build3_v (COND_EXPR, cond, build_empty_stmt (input_location),
 			    tmp);
@@ -11387,6 +11437,89 @@  is_runtime_conformable (gfc_expr *expr1, gfc_expr *expr2)
 }
 
 
+  /* F2018 (7.5.6.3): "When an intrinsic assignment statement is executed
+     (10.2.1.3), if the variable is not an unallocated allocatable variable,
+     it is finalized after evaluation of expr and before the definition of
+     the variable. If the variable is an allocated allocatable variable, or
+     has an allocated allocatable subobject, that would be deallocated by
+     intrinsic assignment, the finalization occurs before the deallocation */
+
+static tree
+gfc_assignment_finalizer_call (gfc_expr *expr1, bool init_flag)
+{
+  stmtblock_t final_block;
+  gfc_init_block (&final_block);
+  symbol_attribute lhs_attr;
+  tree final_expr;
+  tree ptr;
+  tree cond;
+  gfc_se se;
+
+  /* We have to exclude vtable procedures (_copy and _final especially), uses
+     of gfc_trans_assignment_1 in initialization and allocation before trying
+     to build a final call.  */
+  if (!expr1->must_finalize
+      || expr1->symtree->n.sym->attr.artificial
+      || expr1->symtree->n.sym->ns->proc_name->attr.artificial
+      || init_flag)
+    return NULL_TREE;
+
+  if (!(expr1->ts.type == BT_CLASS
+	|| (expr1->ts.type == BT_DERIVED
+	    && gfc_is_finalizable (expr1->ts.u.derived, NULL)))
+      || !gfc_add_finalizer_call (&final_block, expr1))
+    return NULL_TREE;
+
+  lhs_attr = gfc_expr_attr (expr1);
+
+  /* Check allocatable/pointer is allocated/associated.  */
+  if (lhs_attr.allocatable || lhs_attr.pointer)
+    {
+      if (expr1->ts.type == BT_CLASS)
+	{
+	  ptr = gfc_get_class_from_gfc_expr (expr1);
+	  gcc_assert (ptr != NULL_TREE);
+	  ptr = gfc_class_data_get (ptr);
+	  if (lhs_attr.dimension)
+	    ptr = gfc_conv_descriptor_data_get (ptr);
+	}
+      else
+	{
+	  gfc_init_se (&se, NULL);
+	  if (expr1->rank)
+	    {
+	      gfc_conv_expr_descriptor (&se, expr1);
+	      ptr = gfc_conv_descriptor_data_get (se.expr);
+	    }
+	  else
+	    {
+	      gfc_conv_expr (&se, expr1);
+	      ptr = gfc_build_addr_expr (NULL_TREE, se.expr);
+	    }
+	}
+
+      cond = fold_build2_loc (input_location, NE_EXPR, logical_type_node,
+			      ptr, build_zero_cst (TREE_TYPE (ptr)));
+      final_expr = build3_loc (input_location, COND_EXPR, void_type_node,
+			       cond, gfc_finish_block (&final_block),
+			       build_empty_stmt (input_location));
+    }
+  else
+    final_expr = gfc_finish_block (&final_block);
+
+  /* Check optional present.  */
+  if (expr1->symtree->n.sym->attr.optional)
+    {
+      cond = gfc_conv_expr_present (expr1->symtree->n.sym);
+      final_expr = build3_loc (input_location, COND_EXPR, void_type_node,
+			       cond, final_expr,
+			       build_empty_stmt (input_location));
+    }
+
+  return final_expr;
+}
+
+
 static tree
 trans_class_assignment (stmtblock_t *block, gfc_expr *lhs, gfc_expr *rhs,
 			gfc_se *lse, gfc_se *rse, bool use_vptr_copy,
@@ -11394,6 +11527,16 @@  trans_class_assignment (stmtblock_t *block, gfc_expr *lhs, gfc_expr *rhs,
 {
   tree tmp, fcn, stdcopy, to_len, from_len, vptr, old_vptr;
   vec<tree, va_gc> *args = NULL;
+  tree final_expr;
+
+  final_expr = gfc_assignment_finalizer_call (lhs, false);
+  if (final_expr != NULL_TREE)
+    {
+      if (rse->loop)
+	gfc_prepend_expr_to_block (&rse->loop->pre, final_expr);
+      else
+	gfc_add_expr_to_block (block, final_expr);
+    }
 
   /* Store the old vptr so that dynamic types can be compared for
      reallocation to occur or not.  */
@@ -11519,6 +11662,7 @@  trans_class_assignment (stmtblock_t *block, gfc_expr *lhs, gfc_expr *rhs,
     }
 }
 
+
 /* Subroutine of gfc_trans_assignment that actually scalarizes the
    assignment.  EXPR1 is the destination/LHS and EXPR2 is the source/RHS.
    init_flag indicates initialization expressions and dealloc that no
@@ -11542,6 +11686,7 @@  gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
   tree tmp;
   stmtblock_t block;
   stmtblock_t body;
+  tree final_expr;
   bool l_is_temp;
   bool scalar_to_array;
   tree string_length;
@@ -11582,6 +11727,7 @@  gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
      needed at two locations, so do it once only before the information is
      needed.  */
   lhs_attr = gfc_expr_attr (expr1);
+
   is_poly_assign = (use_vptr_copy || lhs_attr.pointer
 		    || (lhs_attr.allocatable && !lhs_attr.dimension))
 		   && (expr1->ts.type == BT_CLASS
@@ -11855,6 +12001,8 @@  gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
 	  else
 	    gfc_add_expr_to_block (&loop.post, tmp2);
 	}
+
+      expr1->must_finalize = 0;
     }
   else if (flag_coarray == GFC_FCOARRAY_LIB
 	   && lhs_caf_attr.codimension && rhs_caf_attr.codimension
@@ -11909,8 +12057,26 @@  gfc_trans_assignment_1 (gfc_expr * expr1, gfc_expr * expr2, bool init_flag,
 				   !(l_is_temp || init_flag) && dealloc,
 				   expr1->symtree->n.sym->attr.codimension);
 
-  /* Add the pre blocks to the body.  */
-  gfc_add_block_to_block (&body, &rse.pre);
+  /* Comply with F2018 (7.5.6.3). Make sure that any finalization code is added
+     after evaluation of the rhs and before reallocation.  */
+  final_expr = gfc_assignment_finalizer_call (expr1, init_flag);
+  if (final_expr)
+    {
+      if (lss == gfc_ss_terminator)
+	{
+	  gfc_add_block_to_block (&block, &rse.pre);
+	  gfc_add_expr_to_block (&block, final_expr);
+	}
+      else
+	{
+	  gfc_add_block_to_block (&body, &rse.pre);
+	  gfc_add_expr_to_block (&loop.code[expr1->rank - 1], final_expr);
+	}
+    }
+  else
+    gfc_add_block_to_block (&body, &rse.pre);
+
+  /* Add the lse pre block to the body  */
   gfc_add_block_to_block (&body, &lse.pre);
   gfc_add_expr_to_block (&body, tmp);
   /* Add the post blocks to the body.  */
diff --git a/gcc/testsuite/gfortran.dg/allocate_with_source_25.f90 b/gcc/testsuite/gfortran.dg/allocate_with_source_25.f90
index 92dc50756d4..de20a147842 100644
--- a/gcc/testsuite/gfortran.dg/allocate_with_source_25.f90
+++ b/gcc/testsuite/gfortran.dg/allocate_with_source_25.f90
@@ -68,4 +68,4 @@  contains
   end function func_foo_a
 
 end program simple_leak
-! { dg-final { scan-tree-dump-times "\>_final" 6 "original" } }
+! { dg-final { scan-tree-dump-times "\>_final" 4 "original" } }