This patch adds a legality check that in a loop over a container that only has
a constant indexing aspect, elements are constant within the loop, and attempts
to modify them are appripriately rejected.
Compiling p.adb must yield:
p.adb:15:07: left hand side of assignment must be a variable
---
with Ada.Containers.Hashed_Sets;
use Ada.Containers;
procedure P is
function Hash (N : Natural) return Hash_Type is
begin
return Hash_Type (N);
end;
package Sets is new Ada.Containers.Hashed_Sets (Natural,
Hash, "=");
S : Sets.Set;
begin
S.Insert (1);
for NConst of S loop
NConst := 0; -- Should not be allowed
end loop;
end;
Tested on x86_64-pc-linux-gnu, committed on trunk
2014-02-04 Ed Schonberg <schonb...@adacore.com>
* exp_ch5.adb (Expand_Iterator_Loop): For a container element
iterator, indicate that the element is a constant if the container
type does not have a variable indexing aspect.
* sem_ch8.adb (Analyze_Object_Renaming): If the entity is already
marked as constant, do not reset its Ekind, to ensure that
container elements in an element loop are not modified if the
container (e.g. a hashed set) only has a constant indexing aspect.
Index: exp_ch5.adb
===================================================================
--- exp_ch5.adb (revision 207465)
+++ exp_ch5.adb (working copy)
@@ -3128,6 +3128,15 @@
Set_Debug_Info_Needed (Id);
+ -- If the container does not have a variable indexing aspect,
+ -- the element is a constant in the loop.
+
+ if No (Find_Value_Of_Aspect
+ (Container_Typ, Aspect_Variable_Indexing))
+ then
+ Set_Ekind (Id, E_Constant);
+ end if;
+
-- If the container holds controlled objects, wrap the loop
-- statements and element renaming declaration with a block.
-- This ensures that the result of Element (Cusor) is
Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb (revision 207465)
+++ sem_ch8.adb (working copy)
@@ -1193,8 +1193,14 @@
end;
end if;
- Set_Ekind (Id, E_Variable);
+ -- Set the Ekind of the entity, unless it has been set already, as is
+ -- the case for the iteration object over a container with no variable
+ -- indexing.
+ if Ekind (Id) /= E_Constant then
+ Set_Ekind (Id, E_Variable);
+ end if;
+
-- Initialize the object size and alignment. Note that we used to call
-- Init_Size_Align here, but that's wrong for objects which have only
-- an Esize, not an RM_Size field.
