+2013-07-08 Javier Miranda <miranda@adacore.com>
+
+ * sem_ch8.adb (Save_Scope_Stack): Adding documentation.
+ (Restore_Scope_Stack): Remove the elements of the list when the
+ visibility of each entity is restored.
+
+2013-07-08 Robert Dewar <dewar@adacore.com>
+
+ * exp_ch9.adb, sem.ads, sem_util.adb: Minor reformatting.
+
2013-07-08 Robert Dewar <dewar@adacore.com>
* sem_ch8.adb, sem_ch8.ads: Minor reformatting.
-- Note: for integer and real literals, the analyzer sets the flag to
-- indicate that the result is a static expression. If the expander
-- generates a literal that does NOT correspond to a static expression,
- -- e.g. by folding an expression whose value is known at compile-time,
+ -- e.g. by folding an expression whose value is known at compile time,
-- but is not technically static, then the caller should reset the
-- Is_Static_Expression flag after analyzing but before resolving.
--
Elmt : Elmt_Id;
begin
- -- Restore visibility of previous scope stack, if any
+ -- Restore visibility of previous scope stack, if any, using the list
+ -- we saved (we use Remove, since this list will not be used again).
- -- Should use Remove_Elmt, so that elements can be reused ???
-
- Elmt := First_Elmt (List);
- while Present (Elmt) loop
+ loop
+ Elmt := Last_Elmt (List);
+ exit when Elmt = No_Elmt;
Set_Is_Immediately_Visible (Node (Elmt));
- Next_Elmt (Elmt);
+ Remove_Last_Elmt (List);
end loop;
+ -- Restore use clauses
+
if SS_Last >= Scope_Stack.First
and then Scope_Stack.Table (SS_Last).Entity /= Standard_Standard
and then Handle_Use
-- Save_Scope_Stack --
----------------------
+ -- Save_Scope_Stack/Restore_Scope_Stack were originally designed to avoid
+ -- consuming any memory. That is, Save_Scope_Stack took care of removing
+ -- from immediate visibility entities and Restore_Scope_Stack took care
+ -- of restoring their visibility analyzing the context of each entity. The
+ -- problem of such approach is that it was fragile and caused unexpected
+ -- visibility problems, and indeed one test was found where there was a
+ -- real problem.
+
+ -- Furthermore, the following experiment was carried out:
+
+ -- - Save_Scope_Stack was modified to store in an Elist1 all those
+ -- entities whose attribute Is_Immediately_Visible is modified
+ -- from True to False.
+
+ -- - Restore_Scope_Stack was modified to store in another Elist2
+ -- all the entities whose attribute Is_Immediately_Visible is
+ -- modified from False to True.
+
+ -- - Extra code was added to verify that all the elements of Elist1
+ -- are found in Elist2
+
+ -- This test show that there may be more occurrences of this problem which
+ -- have not yet been detected. As a result, we replaced that approach by
+ -- the current one in which Save_Scope_Stack returns the list of entities
+ -- whose visibility is changed, and that list is passed to Restore_Scope
+ -- Stack to undo that change. This approach is simpler and safer, although
+ -- it consumes more memory.
+
function Save_Scope_Stack (Handle_Use : Boolean := True) return Elist_Id is
Result : constant Elist_Id := New_Elmt_List;
E : Entity_Id;
-- Remove_From_Visibility --
----------------------------
- -- Need comment on why we do this instead of old approach???
-
procedure Remove_From_Visibility (E : Entity_Id) is
begin
if Is_Immediately_Visible (E) then
if Known_Static_Esize (Typ) then
Size := UI_To_Int (Esize (Typ));
- -- If the Esize (Object_Size) is unknown at compile-time, look at the
- -- RM_Size (Value_Size) since it may have been set by an explicit rep
- -- item.
+ -- If the Esize (Object_Size) is unknown at compile time, look at the
+ -- RM_Size (Value_Size) which may have been set by an explicit rep item.
elsif Known_Static_RM_Size (Typ) then
Size := UI_To_Int (RM_Size (Typ));
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