-- --
-- S p e c --
-- --
--- $Revision: 1.22 $ --
--- --
--- Copyright (C) 1992,1993,1994,1995,1996 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2008, 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- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- Public License distributed with GNAT; see file COPYING3. If not, go to --
+-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
--- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- Implicit Types --
--------------------
- -- Implicit types are types and subtypes created by the semantic phase
- -- or the expander to reflect the underlying semantics. These could be
- -- generated by building trees for corresponding declarations and then
- -- analyzing these trees, but there are three reasons for not doing this:
+ -- Implicit types (Itypes) are types and subtypes created by the semantic
+ -- phase or the expander to reflect the underlying semantics. These could
+ -- be generated by building trees for corresponding declarations and then
+ -- analyzing these trees, but there are three reasons for not doing this
+ -- in some cases:
-- 1. The declarations would require more tree nodes
-- The type declaration declaring an Itype must be analyzed with checks
-- off because this declaration has not been inserted in the tree (if it
- -- has been then it is not an itype), and hence checks that would be
+ -- has been then it is not an Itype), and hence checks that would be
-- generated during the analysis cannot be inserted in the tree. At any
- -- rate, itype analysis should always be done with checks off, otherwise
+ -- rate, Itype analysis should always be done with checks off, otherwise
-- duplicate checks will most likely be emitted.
-- Unlike types declared explicitly, implicit types are defined on first
-- or not to copy a referenced Itype. If the associated node is part of
-- the tree to be copied by New_Copy_Tree, then (since the idea of the
-- call to New_Copy_Tree is to create a complete duplicate of a tree,
- -- as though it had appeared separately int he source), the Itype in
+ -- as though it had appeared separately in the source), the Itype in
-- question is duplicated as part of the New_Copy_Tree processing.
- -----------------
- -- Subprograms --
- -----------------
+ -- As a consequence of this copying mechanism, the association between
+ -- Itypes and associated nodes must be one-to-one: several Itypes must
+ -- not share an associated node. For example, the semantic decoration
+ -- of an array aggregate generates several Itypes: for each index subtype
+ -- and for the array subtype. The associated node of each index subtype
+ -- is the corresponding range expression.
+
+ -- Notes on the use of the Parent field of an Itype
+
+ -- In some cases, we do create a declaration node for an itype, and in
+ -- such cases, the Parent field of the Itype points to this declaration
+ -- in the normal manner. This case can be detected by checking for a
+ -- non-empty Parent field referencing a declaration whose Defining_Entity
+ -- is the Itype in question.
+
+ -- In some other cases, where we don't generate such a declaration, as
+ -- described above, the Itype is attached to the tree implicitly by being
+ -- referenced elsewhere, e.g. as the Etype of some object. In this case
+ -- the Parent field may be Empty.
+
+ -- In other cases where we don't generate a declaration for the Itype,
+ -- the Itype may be attached to an arbitrary node in the tree, using
+ -- the Parent field. This Parent field may even reference a declaration
+ -- for a related different entity (hence the description of the tests
+ -- needed for the case where a declaration for the Itype is created).
+
+ ------------------
+ -- Create_Itype --
+ ------------------
function Create_Itype
(Ekind : Entity_Kind;
Related_Id : Entity_Id := Empty;
Suffix : Character := ' ';
Suffix_Index : Nat := 0;
- Scope_Id : Entity_Id := Current_Scope)
- return Entity_Id;
- -- Used to create a new Itype.
+ Scope_Id : Entity_Id := Current_Scope) return Entity_Id;
+ -- Used to create a new Itype
--
- -- Related_Nod is the node for which this Itype was created. It is
- -- set as the Associated_Node_For_Itype of the new itype. The Sloc of
- -- the new Itype is that of this node.
+ -- Related_Nod is the node for which this Itype was created. It is
+ -- set as the Associated_Node_For_Itype of the new Itype. The Sloc of
+ -- the new Itype is that of this node.
--
- -- Related_Id is present only if the implicit type name may be referenced
- -- as a public symbol, and thus needs a unique external name. The name
- -- is created by a call to:
+ -- Related_Id is present only if the implicit type name may be referenced
+ -- as a public symbol, and thus needs a unique external name. The name
+ -- is created by a call to:
--
- -- New_External_Name (Chars (Related_Id), Suffix, Suffix_Index, 'T')
+ -- New_External_Name (Chars (Related_Id), Suffix, Suffix_Index, 'T')
--
- -- If the implicit type does not need an external name, then the
- -- Related_Id parameter is omitted (and hence Empty). In this case
- -- Suffix and Suffix_Index are ignored and the implicit type name is
- -- created by a call to New_Internal_Name ('T').
+ -- If the implicit type does not need an external name, then the
+ -- Related_Id parameter is omitted (and hence Empty). In this case
+ -- Suffix and Suffix_Index are ignored and the implicit type name is
+ -- created by a call to New_Internal_Name ('T').
--
- -- Note that in all cases, the name starts with "T". This is used
- -- to identify implicit types in the error message handling circuits.
+ -- Note that in all cases, the name starts with "T". This is used
+ -- to identify implicit types in the error message handling circuits.
--
-- The Scope_Id parameter specifies the scope of the created type, and
-- is normally the Current_Scope as shown, but can be set otherwise.
+ --
+ -- The size/align fields are initialized to unknown (Uint_0).
+ --
+ -- If Ekind is in Access_Subprogram_Kind, Can_Use_Internal_Rep is set True,
+ -- unless Always_Compatible_Rep_On_Target is True.
+
+ ---------------------------------
+ -- Create_Null_Excluding_Itype --
+ ---------------------------------
+
+ function Create_Null_Excluding_Itype
+ (T : Entity_Id;
+ Related_Nod : Node_Id;
+ Scope_Id : Entity_Id := Current_Scope) return Entity_Id;
+ -- Ada 2005 (AI-231): T is an access type and this subprogram creates and
+ -- returns an internal access-subtype declaration of T that has the null
+ -- exclusion attribute set to True.
+ --
+ -- Usage of null-excluding Itypes
+ -- ------------------------------
+ --
+ -- type T1 is access ...
+ -- type T2 is not null T1;
+ --
+ -- type Rec is record
+ -- Comp : not null T1;
+ -- end record;
+ --
+ -- type Arr is array (...) of not null T1;
+ --
+ -- Instead of associating the not-null attribute with the defining ids of
+ -- these declarations, we generate an internal subtype declaration of T1
+ -- that has the null exclusion attribute set to true.
end Itypes;
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