For users, 'Old attribute references are only allowed within
postcondition expressions. Internally, the FE may build trees that
transiently (before some subsequent transformation) violate these rules;
this is ok, but these violations were being incorrectly flagged in some
cases. Fix this problem.
The customer's example for this ticket also demonstrates a second
problem. Exp_Util.Insert_Actions was willing to take an action (e.g.,
the constraint check for an array indexing expression) that contains a
reference to the loop parameter of a
N_Iterated_Component/Element_Association and insert it in the tree
somewhere above that node, so that the reference ends up outside of the
scope of the declaration it refers to. This leads to a bugbox failure
(gigi is understandably unhappy with the resulting malformed tree). Fix
this too.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_attr.adb (Analyze_Attribute_Old_Result): Permit an
attribute reference inside a compiler-generated _Postconditions
procedure. In this case, Subp_Decl is assigned the declaration
of the enclosing subprogram.
* exp_util.adb (Insert_Actions): When climbing up the tree
looking for an insertion point, do not climb past an
N_Iterated_Component/Element_Association, since this could
result in inserting a reference to a loop parameter at a
location outside of the scope of that loop parameter. On the
other hand, be careful to preserve existing behavior in the case
of an N_Component_Association node.diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -7619,8 +7619,18 @@ package body Exp_Util is
| N_Iterated_Component_Association
| N_Iterated_Element_Association
=>
- if Nkind (Parent (P)) = N_Aggregate
- and then Present (Loop_Actions (P))
+ if Nkind (Parent (P)) in N_Aggregate | N_Delta_Aggregate
+
+ -- We must not climb up out of an N_Iterated_xxx_Association
+ -- because the actions might contain references to the loop
+ -- parameter. But it turns out that setting the Loop_Actions
+ -- attribute in the case of an N_Component_Association
+ -- when the attribute was not already set can lead to
+ -- (as yet not understood) bugboxes (gcc failures that are
+ -- presumably due to malformed trees). So we don't do that.
+
+ and then (Nkind (P) /= N_Component_Association
+ or else Present (Loop_Actions (P)))
then
if Is_Empty_List (Loop_Actions (P)) then
Set_Loop_Actions (P, Ins_Actions);
diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -1413,6 +1413,15 @@ package body Sem_Attr is
return;
end if;
+ -- 'Old attribute reference ok in a _Postconditions procedure
+
+ elsif Nkind (Prag) = N_Subprogram_Body
+ and then not Comes_From_Source (Prag)
+ and then Nkind (Corresponding_Spec (Prag)) = N_Defining_Identifier
+ and then Chars (Corresponding_Spec (Prag)) = Name_uPostconditions
+ then
+ null;
+
-- Otherwise the placement of the attribute is illegal
else
@@ -1424,6 +1433,15 @@ package body Sem_Attr is
if Nkind (Prag) = N_Aspect_Specification then
Subp_Decl := Parent (Prag);
+ elsif Nkind (Prag) = N_Subprogram_Body then
+ declare
+ Enclosing_Scope : constant Node_Id :=
+ Scope (Corresponding_Spec (Prag));
+ begin
+ pragma Assert (Postconditions_Proc (Enclosing_Scope)
+ = Corresponding_Spec (Prag));
+ Subp_Decl := Parent (Parent (Enclosing_Scope));
+ end;
else
Subp_Decl := Find_Related_Declaration_Or_Body (Prag);
end if;
