The patch implements properly the rule given in this Ada issue. The check is
purely syntactic and does not depend on whether the designated type is itself a
null excluding access type.
Compiling the following in Ada 2012 mode must yield:
alloc.adb:23:16:
an allocator with a subtype indication cannot have a null exclusion
---
-- AI05-104 : an uninitialzed allocated cannot carry a null exclusion.
procedure Alloc is
begin
declare
type R (D : Integer) is record
Val : Integer;
end record;
type Ptr is not null access all R;
begin
if new Ptr /= null then -- OK
raise Program_Error;
end if;
end;
declare
type T is tagged null record;
type Ptr is access all T;
type Link is access all Ptr;
Thing : Link;
begin
Thing := new not null Ptr; -- Error
end;
end;
Tested on x86_64-pc-linux-gnu, committed on trunk
2012-12-05 Ed Schonberg <schonb...@adacore.com>
* par-ch4.adb (P_Allocator): In Ada 2012 (AI05-0104) an
uninitialized allocator cannot carry an explicit not null
indicator.
* sem_ch4.adb (Analyze_Allocator): Remove code that implements
the check for AI05-0104, the check is syntactic and performed
in the parser.
Index: par-ch4.adb
===================================================================
--- par-ch4.adb (revision 194207)
+++ par-ch4.adb (working copy)
@@ -2928,6 +2928,18 @@
Set_Expression
(Alloc_Node,
P_Subtype_Indication (Type_Node, Null_Exclusion_Present));
+
+ -- AI05-0104 : an explicit null exclusion is not allowed for an
+ -- allocator without initialization. In previous versions of the
+ -- language it just raises constraint error.
+
+ if Ada_Version >= Ada_2012
+ and then Null_Exclusion_Present
+ then
+ Error_Msg_N
+ ("an allocator with a subtype indication "
+ & "cannot have a null exclusion", Alloc_Node);
+ end if;
end if;
return Alloc_Node;
Index: sem_ch4.adb
===================================================================
--- sem_ch4.adb (revision 194204)
+++ sem_ch4.adb (working copy)
@@ -631,12 +631,7 @@
Reason => CE_Null_Not_Allowed);
begin
- if Ada_Version >= Ada_2012 then
- Error_Msg_N
- ("an uninitialized allocator cannot have"
- & " a null exclusion", N);
-
- elsif Expander_Active then
+ if Expander_Active then
Insert_Action (N, Not_Null_Check);
Analyze (Not_Null_Check);
