1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                S Y S T E M . E X C E P T I O N _ T R A C E S             --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--                     Copyright (C) 2000-2015, AdaCore                     --
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.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This package provides an interface allowing to control *automatic* output
33--  to standard error upon exception occurrences (as opposed to explicit
34--  generation of traceback information using System.Traceback).
35
36--  This output includes the basic information associated with the exception
37--  (name, message) as well as a backtrace of the call chain at the point
38--  where the exception occurred. This backtrace is only output if the call
39--  chain information is available, depending if the binder switch dedicated
40--  to that purpose has been used or not.
41
42--  The default backtrace is in the form of absolute code locations which may
43--  be converted to corresponding source locations using the addr2line utility
44--  or from within GDB. Please refer to System.Traceback for information about
45--  what is necessary to be able to exploit this possibility.
46
47--  The backtrace output can also be customized by way of a "decorator" which
48--  may return any string output in association with a provided call chain.
49--  The decorator replaces the default backtrace mentioned above.
50
51--  On systems that use DWARF debugging output, then if the "-g" compiler
52--  switch and the "-Es" binder switch are used, the decorator is automatically
53--  set to Symbolic_Traceback.
54
55with System.Traceback_Entries;
56
57package System.Exception_Traces is
58
59   --  The following defines the exact situations in which raises will
60   --  cause automatic output of trace information.
61
62   type Trace_Kind is
63     (Every_Raise,
64      --  Denotes the initial raise event for any exception occurrence, either
65      --  explicit or due to a specific language rule, within the context of a
66      --  task or not.
67
68      Unhandled_Raise,
69      --  Denotes the raise events corresponding to exceptions for which there
70      --  is no user defined handler. This includes unhandled exceptions in
71      --  task bodies.
72
73      Unhandled_Raise_In_Main
74      --  Same as Unhandled_Raise, except exceptions in task bodies are not
75      --  included.
76     );
77
78   --  The following procedures can be used to activate and deactivate
79   --  traces identified by the above trace kind values.
80
81   procedure Trace_On (Kind : Trace_Kind);
82   --  Activate the traces denoted by Kind
83
84   procedure Trace_Off;
85   --  Stop the tracing requested by the last call to Trace_On.
86   --  Has no effect if no such call has ever occurred.
87
88   --  The following provide the backtrace decorating facilities
89
90   type Traceback_Decorator is access
91     function (Traceback : Traceback_Entries.Tracebacks_Array) return String;
92   --  A backtrace decorator is a function which returns the string to be
93   --  output for a call chain provided by way of a tracebacks array.
94
95   procedure Set_Trace_Decorator (Decorator : Traceback_Decorator);
96   --  Set the decorator to be used for future automatic outputs. Restore the
97   --  default behavior if the provided access value is null.
98   --
99   --  Note: System.Traceback.Symbolic.Symbolic_Traceback may be used as the
100   --  Decorator, to get a symbolic traceback. This will cause a significant
101   --  cpu and memory overhead on some platforms.
102   --
103   --  Note: The Decorator is called when constructing the
104   --  Exception_Information; that needs to be taken into account
105   --  if the Decorator has any side effects.
106
107end System.Exception_Traces;
108