This patch corrects the detection of a proper aliased view of a type in the
context of attributes Access and Unchecked_Access.
Tested on x86_64-pc-linux-gnu, committed on trunk
2012-01-23 Hristian Kirtchev <kirtc...@adacore.com>
* freeze.adb (Check_Current_Instance): Issue an
error when the prefix of 'Unchecked_Access or 'Access does not
denote a legal aliased view of a type.
(Freeze_Record_Type): Do not halt the processing of record components
once the Has_Controlled_Component is set as this bypasses the remaining
checks.
(Is_Aliased_View_Of_Type): New routine.
Index: freeze.adb
===================================================================
--- freeze.adb (revision 183406)
+++ freeze.adb (working copy)
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@@ -1592,14 +1592,93 @@
procedure Check_Current_Instance (Comp_Decl : Node_Id) is
- Rec_Type : constant Entity_Id :=
- Scope (Defining_Identifier (Comp_Decl));
+ function Is_Aliased_View_Of_Type (Typ : Entity_Id) return Boolean;
+ -- Determine whether Typ is compatible with the rules for aliased
+ -- views of types as defined in RM 3.10 in the various dialects.
- Decl : constant Node_Id := Parent (Rec_Type);
-
function Process (N : Node_Id) return Traverse_Result;
-- Process routine to apply check to given node
+ -----------------------------
+ -- Is_Aliased_View_Of_Type --
+ -----------------------------
+
+ function Is_Aliased_View_Of_Type (Typ : Entity_Id) return Boolean is
+ Typ_Decl : constant Node_Id := Parent (Typ);
+
+ begin
+ -- Common case
+
+ if Nkind (Typ_Decl) = N_Full_Type_Declaration
+ and then Limited_Present (Type_Definition (Typ_Decl))
+ then
+ return True;
+
+ -- The following paragraphs describe what a legal aliased view of
+ -- a type is in the various dialects of Ada.
+
+ -- Ada 95
+
+ -- The current instance of a limited type, and a formal parameter
+ -- or generic formal object of a tagged type.
+
+ -- Ada 95 limited type
+ -- * Type with reserved word "limited"
+ -- * A protected or task type
+ -- * A composite type with limited component
+
+ elsif Ada_Version <= Ada_95 then
+ return Is_Limited_Type (Typ);
+
+ -- Ada 2005
+
+ -- The current instance of a limited tagged type, a protected
+ -- type, a task type, or a type that has the reserved word
+ -- "limited" in its full definition ... a formal parameter or
+ -- generic formal object of a tagged type.
+
+ -- Ada 2005 limited type
+ -- * Type with reserved word "limited", "synchronized", "task"
+ -- or "protected"
+ -- * A composite type with limited component
+ -- * A derived type whose parent is a non-interface limited type
+
+ elsif Ada_Version = Ada_2005 then
+ return
+ (Is_Limited_Type (Typ) and then Is_Tagged_Type (Typ))
+ or else
+ (Is_Derived_Type (Typ)
+ and then not Is_Interface (Etype (Typ))
+ and then Is_Limited_Type (Etype (Typ)));
+
+ -- Ada 2012 and beyond
+
+ -- The current instance of an immutably limited type ... a formal
+ -- parameter or generic formal object of a tagged type.
+
+ -- Ada 2012 limited type
+ -- * Type with reserved word "limited", "synchronized", "task"
+ -- or "protected"
+ -- * A composite type with limited component
+ -- * A derived type whose parent is a non-interface limited type
+ -- * An incomplete view
+
+ -- Ada 2012 immutably limited type
+ -- * Explicitly limited record type
+ -- * Record extension with "limited" present
+ -- * Non-formal limited private type that is either tagged
+ -- or has at least one access discriminant with a default
+ -- expression
+ -- * Task type, protected type or synchronized interface
+ -- * Type derived from immutably limited type
+
+ else
+ return
+ Is_Immutably_Limited_Type (Typ)
+ or else Is_Incomplete_Type (Typ);
+ end if;
+ end Is_Aliased_View_Of_Type;
+
-------------
-- Process --
-------------
@@ -1628,24 +1707,15 @@
procedure Traverse is new Traverse_Proc (Process);
+ -- Local variables
+
+ Rec_Type : constant Entity_Id :=
+ Scope (Defining_Identifier (Comp_Decl));
+
-- Start of processing for Check_Current_Instance
begin
- -- In Ada 95, the (imprecise) rule is that the current instance
- -- of a limited type is aliased. In Ada 2005, limitedness must be
- -- explicit: either a tagged type, or a limited record.
-
- if Is_Limited_Type (Rec_Type)
- and then (Ada_Version < Ada_2005 or else Is_Tagged_Type (Rec_Type))
- then
- return;
-
- elsif Nkind (Decl) = N_Full_Type_Declaration
- and then Limited_Present (Type_Definition (Decl))
- then
- return;
-
- else
+ if not Is_Aliased_View_Of_Type (Rec_Type) then
Traverse (Comp_Decl);
end if;
end Check_Current_Instance;
@@ -2158,18 +2228,16 @@
(Etype (Comp)))))
then
Set_Has_Controlled_Component (Rec);
- exit;
end if;
if Has_Unchecked_Union (Etype (Comp)) then
Set_Has_Unchecked_Union (Rec);
end if;
+ -- Scan component declaration for likely misuses of current
+ -- instance, either in a constraint or a default expression.
+
if Has_Per_Object_Constraint (Comp) then
-
- -- Scan component declaration for likely misuses of current
- -- instance, either in a constraint or a default expression.
-
Check_Current_Instance (Parent (Comp));
end if;
