===================================================================
@@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
+-- Copyright (C) 1992-2015, 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- --
@@ -690,41 +690,6 @@
Obj_Ref : Node_Id;
Curr : Entity_Id;
- function May_Be_External_Call return Boolean;
- -- If the 'Access is to a local operation, but appears in a context
- -- where it may lead to a call from outside the object, we must treat
- -- this as an external call. Clearly we cannot tell without full
- -- flow analysis, and a subsequent call that uses this 'Access may
- -- lead to a bounded error (trying to seize locks twice, e.g.). For
- -- now we treat 'Access as a potential external call if it is an actual
- -- in a call to an outside subprogram.
-
- --------------------------
- -- May_Be_External_Call --
- --------------------------
-
- function May_Be_External_Call return Boolean is
- Subp : Entity_Id;
- Par : Node_Id := Parent (N);
-
- begin
- -- Account for the case where the Access attribute is part of a
- -- named parameter association.
-
- if Nkind (Par) = N_Parameter_Association then
- Par := Parent (Par);
- end if;
-
- if Nkind (Par) in N_Subprogram_Call
- and then Is_Entity_Name (Name (Par))
- then
- Subp := Entity (Name (Par));
- return not In_Open_Scopes (Scope (Subp));
- else
- return False;
- end if;
- end May_Be_External_Call;
-
-- Start of processing for Expand_Access_To_Protected_Op
begin
@@ -733,15 +698,15 @@
-- protected body of the current enclosing operation.
if Is_Entity_Name (Pref) then
- if May_Be_External_Call then
- Sub :=
- New_Occurrence_Of (External_Subprogram (Entity (Pref)), Loc);
- else
- Sub :=
- New_Occurrence_Of
- (Protected_Body_Subprogram (Entity (Pref)), Loc);
- end if;
+ -- All indirect calls are external calls, so must do locking and
+ -- barrier reevaluation, even if the 'Access occurs within the
+ -- protected body. Hence the call to External_Subprogram, as opposed
+ -- to Protected_Body_Subprogram, below. See RM-9.5(5). This means
+ -- that indirect calls from within the same protected body will
+ -- deadlock, as allowed by RM-9.5.1(8,15,17).
+ Sub := New_Occurrence_Of (External_Subprogram (Entity (Pref)), Loc);
+
-- Don't traverse the scopes when the attribute occurs within an init
-- proc, because we directly use the _init formal of the init proc in
-- that case.
an indirect call through an access-to-protected-subprogram value is always considered an external call. This patch makes that happen (previously, the compiler was using internal calls in some cases). The following test should run to completion, silently. (Before the bug fix, it would hang, because the call "V_Acc.all;" was not reevaluating the barriers, so the call "PO.P;" would never proceed.) package External_Indirect_Calls is protected PO is procedure Init; entry P; procedure V; private B : Boolean := True; end PO; V_Acc : access protected procedure; end External_Indirect_Calls; package body External_Indirect_Calls is protected body PO is procedure Init is begin V_Acc := V'Access; end Init; entry P when not B is begin B := True; end P; procedure V is begin B := False; end V; end PO; end External_Indirect_Calls; procedure External_Indirect_Calls.Main is task T; task body T is begin PO.P; end T; begin PO.Init; delay 0.001; V_Acc.all; end External_Indirect_Calls.Main; Tested on x86_64-pc-linux-gnu, committed on trunk 2015-02-20 Bob Duff <duff@adacore.com> * exp_attr.adb (May_Be_External_Call): Remove this. There is no need for the compiler to guess whether the call is internal or external -- it is always external. (Expand_Access_To_Protected_Op): For P'Access, where P is a protected subprogram, always create a pointer to the External_Subprogram.