gdb/mi: New commands to catch C++ exceptions

Adds some MI commands to catch C++ exceptions.  The new commands are
-catch-throw, -catch-rethrow, and -catch-catch, these all correspond
to the CLI commands 'catch throw', 'catch rethrow', and 'catch catch'.

Each MI command takes two optional arguments, '-t' has the effect of
calling 'tcatch' instead of 'catch', for example:

   (gdb)
   -catch-throw -t

Is the same as:

   (gdb) tcatch throw

There is also a '-r REGEXP' argument that can supply a regexp to match
against the exception type, so:

   (gdb)
   -catch-catch -r PATTERN

Is the same as:

   (gdb) catch catch PATTERN

The change in print_mention_exception_catchpoint might seem a little
strange; changing the output from using ui_out::field_int and
ui_out::text to using  ui_out::message.

The print_mention_exception_catchpoint is used as the 'print_mention'
method for the exception catchpoint breakpoint object.  Most of the
other 'print_mention' methods (see breakpoint.c) use either
printf_filtered, of ui_out::message.  Using field_int was causing an
unexpected field to be added to the MI output.  Here's the output
without the change in print_mention_exception_catchpoint:

    (gdb)
    -catch-throw
    ^done,bkptno="1",bkpt={number="1",type="breakpoint",disp="keep",
                           enabled="y",addr="0x00000000004006c0",
                           what="exception throw",catch-type="throw",
                           thread-groups=["i1"],times="0"}

Notice the breakpoint number appears in both the 'bkptno' field, and
the 'number' field within the 'bkpt' tuple.  Here's the output with
the change in print_mention_exception_catchpoint:

    (gdb)
    -catch-throw
    ^done,bkpt={number="1",type="breakpoint",disp="keep",
                enabled="y",addr="0x00000000004006c0",
                what="exception throw",catch-type="throw",
                thread-groups=["i1"],times="0"}

gdb/ChangeLog:

	* NEWS: Mention new MI commands.
	* break-catch-throw.c (enum exception_event_kind): Move to
	breakpoint.h.
	(print_mention_exception_catchpoint): Output text as a single
	message.
	(catch_exception_command_1): Rename to...
	(catch_exception_event): ...this, make non-static, update header
	command, and change some parameter types.
	(catch_catch_command): Update for changes to
	catch_exception_command_1.
	(catch_throw_command): Likewise.
	(catch_rethrow_command): Likewise.
	* breakpoint.c (enum exception_event_kind): Delete.
	* breakpoint.h (enum exception_event_kind): Moved here from
	break-catch-throw.c.
	(catch_exception_event): Declare.
	* mi/mi-cmd-catch.c (mi_cmd_catch_exception_event): New function.
	(mi_cmd_catch_throw): New function.
	(mi_cmd_catch_rethrow): New function.
	(mi_cmd_catch_catch): New function.
	* mi/mi-cmds.c (mi_cmds): Add 'catch-throw', 'catch-rethrow', and
	'catch-catch' entries.
	* mi/mi-cmds.h (mi_cmd_catch_throw): Declare.
	(mi_cmd_catch_rethrow): Declare.
	(mi_cmd_catch_catch): Declare.

gdb/doc/ChangeLog:

	* gdb.texinfo (GDB/MI Catchpoint Commands): Add menu entry to new
	node.
	(C++ Exception GDB/MI Catchpoint Commands): New node to describe
	new MI commands.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-catch-cpp-exceptions.cc: New file.
	* gdb.mi/mi-catch-cpp-exceptions.exp: New file.
	* lib/mi-support.exp (mi_expect_stop): Handle 'exception-caught'
	as a stop reason.

1 files changed, 73 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.cc b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.cc
new file mode 100644
index 0000000..cacda46
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.cc
@@ -0,0 +1,73 @@
+/* Copyright 2019 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT 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
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+class my_exception
+{
+private:
+  int m_value;
+
+public:
+  my_exception (int v)
+    : m_value (v)
+  {
+    /* Nothing.  */
+  }
+};
+
+void
+bar ()
+{
+  my_exception ex (4);
+  throw ex;	/* Throw 1.  */
+}
+
+void
+foo ()
+{
+  for (int i = 0; i < 2; ++i)
+    {
+      try
+	{
+	  bar ();
+	}
+      catch (const my_exception &ex)	/* Catch 1.  */
+	{
+	  if (i == 1)
+	    throw;	/* Throw 2.  */
+	}
+    }
+}
+
+int
+main ()
+{
+  for (int i = 0; i < 2; ++i)
+    {
+      try
+	{
+	  foo ();
+	}
+      catch (const my_exception &ex)	/* Catch 2.  */
+	{
+	  if (i == 1)
+	    return 1;	/* Stop here.  */
+	}
+    }
+
+  return 0;
+}
+