1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                             S E M _ S M E M                              --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 1998-2008, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
17-- for  more details.  You should have  received  a copy of the GNU General --
18-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
19-- http://www.gnu.org/licenses for a complete copy of the license.          --
20--                                                                          --
21-- GNAT was originally developed  by the GNAT team at  New York University. --
22-- Extensive contributions were provided by Ada Core Technologies Inc.      --
23--                                                                          --
24------------------------------------------------------------------------------
25
26with Atree;   use Atree;
27with Einfo;   use Einfo;
28with Errout;  use Errout;
29with Namet;   use Namet;
30with Sem_Aux; use Sem_Aux;
31with Sinfo;   use Sinfo;
32with Snames;  use Snames;
33
34package body Sem_Smem is
35
36   function Contains_Access_Type (T : Entity_Id) return Boolean;
37   --  This function determines if type T is an access type, or contains
38   --  a component (array, record, protected type cases) that contains
39   --  an access type (recursively defined in the appropriate manner).
40
41   ----------------------
42   -- Check_Shared_Var --
43   ----------------------
44
45   procedure Check_Shared_Var
46     (Id : Entity_Id;
47      T  : Entity_Id;
48      N  : Node_Id)
49   is
50   begin
51      --  We cannot tolerate aliased variables, because they might be
52      --  modified via an aliased pointer, and we could not detect that
53      --  this was happening (to update the corresponding shared memory
54      --  file), so we must disallow all use of Aliased
55
56      if Aliased_Present (N) then
57         Error_Msg_N
58           ("aliased variables " &
59            "not supported in Shared_Passive partitions",
60            N);
61
62      --  We can't support access types at all, since they are local
63      --  pointers that cannot in any simple way be transmitted to other
64      --  partitions.
65
66      elsif Is_Access_Type (T) then
67         Error_Msg_N
68           ("access type variables " &
69            "not supported in Shared_Passive partitions",
70            Id);
71
72      --  We cannot tolerate types that contain access types, same reasons
73
74      elsif Contains_Access_Type (T) then
75         Error_Msg_N
76           ("types containing access components " &
77            "not supported in Shared_Passive partitions",
78            Id);
79
80      --  Objects with default-initialized types will be rejected when
81      --  the initialization code is generated. However we must flag tasks
82      --  earlier on, to prevent expansion of stream attributes that is
83      --  bound to fail.
84
85      elsif Has_Task (T) then
86         Error_Msg_N
87           ("Shared_Passive partitions cannot contain tasks", Id);
88
89      --  Currently we do not support unconstrained record types, since we
90      --  use 'Write to write out values. This could probably be special
91      --  cased and handled in the future if necessary.
92
93      elsif Is_Record_Type (T)
94        and then not Is_Constrained (T)
95      then
96         Error_Msg_N
97           ("unconstrained variant records " &
98            "not supported in Shared_Passive partitions",
99            Id);
100      end if;
101   end Check_Shared_Var;
102
103   --------------------------
104   -- Contains_Access_Type --
105   --------------------------
106
107   function Contains_Access_Type (T : Entity_Id) return Boolean is
108      C : Entity_Id;
109
110   begin
111      if Is_Access_Type (T) then
112         return True;
113
114      elsif Is_Array_Type (T) then
115         return Contains_Access_Type (Component_Type (T));
116
117      elsif Is_Record_Type (T) then
118         if Has_Discriminants (T) then
119            C := First_Discriminant (T);
120            while Present (C) loop
121               if Comes_From_Source (C) then
122                  return True;
123               else
124                  C := Next_Discriminant (C);
125               end if;
126            end loop;
127         end if;
128
129         C := First_Component (T);
130         while Present (C) loop
131
132            --  For components, ignore internal components other than _Parent
133
134            if Comes_From_Source (T)
135              and then
136                (Chars (C) = Name_uParent
137                  or else
138                 not Is_Internal_Name (Chars (C)))
139              and then Contains_Access_Type (Etype (C))
140            then
141               return True;
142            else
143               C := Next_Component (C);
144            end if;
145         end loop;
146
147         return False;
148
149      elsif Is_Protected_Type (T) then
150         return Contains_Access_Type (Corresponding_Record_Type (T));
151
152      else
153         return False;
154      end if;
155   end Contains_Access_Type;
156
157end Sem_Smem;
158