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.

2 files changed, 270 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;
+}
+
diff --git a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
new file mode 100644
index 0000000..b5dfbe6
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
@@ -0,0 +1,197 @@
+# Copyright 2019 Free Software Foundation, Inc.
+
+# 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/>.
+
+# Test the -catch-throw, -catch-rethrow, and -catch-catch MI commands.
+
+if { [skip_cplus_tests] } { continue }
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+standard_testfile .cc
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug c++}] != "" } {
+    untested "failed to compile"
+    return -1
+}
+
+# Grab some line numbers we'll need.
+set catch_1_lineno [gdb_get_line_number "Catch 1"]
+set catch_2_lineno [gdb_get_line_number "Catch 2"]
+set throw_1_lineno [gdb_get_line_number "Throw 1"]
+set throw_2_lineno [gdb_get_line_number "Throw 2"]
+set main_lineno [gdb_get_line_number "Stop here"]
+
+# Restart this test, load the test binary and set a breakpoint in
+# main.
+proc restart_for_test {} {
+    global srcdir subdir binfile srcfile
+    global main_lineno
+
+    if {[mi_gdb_start]} {
+	continue
+    }
+
+    mi_delete_breakpoints
+    mi_gdb_reinitialize_dir $srcdir/$subdir
+    mi_gdb_load ${binfile}
+
+    mi_runto main
+
+    mi_create_breakpoint \
+	"$srcfile:${main_lineno}" "break before exiting program" \
+	-disp keep -func "main.*" \
+	-file ".*mi-catch-cpp-exceptions.cc" -line ${main_lineno}
+}
+
+# Issue an -exec-continue then wait for GDB to catch a C++ exception
+# event in FUNC on LINE.  Use TESTNAME to make tests unique.
+proc continue_to_next_exception { func line testname } {
+    global hex
+
+    mi_send_resuming_command "exec-continue" \
+	"exec-continue"
+    mi_expect_stop "exception-caught" ".*" ".*" ".*" ".*" \
+	{} "run until an exception is caught: $testname"
+    mi_gdb_test "-stack-list-frames 1 1" \
+	"\\^done,stack=\\\[frame=\{level=\"1\",addr=\"$hex\",func=\"${func}\",.*,line=\"${line}\".*\}\\\]" \
+	"check previous frame: $testname"
+}
+
+# Issue an -exec-continue and stop at the breakpoint in main.
+proc continue_to_breakpoint_in_main {} {
+    global main_lineno
+
+    mi_send_resuming_command "exec-continue" "exec-continue to main"
+    mi_expect_stop "breakpoint-hit" "main" ".*" ".*" "${main_lineno}" \
+	{.* disp="keep"} "run until breakpoint in main"
+}
+
+# TYPE is one of throw, rethrow, or catch.  This proc creates a catch
+# point using -catch-TYPE.  The optional string EXTRA is any extra
+# arguments to pass when setting up the catchpoint.
+proc setup_catchpoint {type {extra ""}} {
+    global decimal
+    mi_gdb_test "-catch-${type} ${extra}" \
+	"\\^done,bkpt=\{number=\"$decimal\".*what=\"exception ${type}\",catch-type=\"${type}\".*\}" \
+	"Setup -catch-${type}"
+}
+
+# Ensure that -catch-throw will catch only throws and nothing else.
+with_test_prefix "-catch-throw" {
+    restart_for_test
+    setup_catchpoint "throw"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 1"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 2"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 3"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 4"
+    continue_to_breakpoint_in_main
+}
+
+# Ensure that -catch-rethrow catches only rethrows and nothing else.
+with_test_prefix "-catch-rethrow" {
+    restart_for_test
+    setup_catchpoint "rethrow"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 1"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 2"
+    continue_to_breakpoint_in_main
+}
+
+# Ensure that -catch-catch catches only catch points, and nothing
+# else.
+with_test_prefix "-catch-catch" {
+    restart_for_test
+    setup_catchpoint "catch"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 1"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 2"
+    continue_to_next_exception "main" "${catch_2_lineno}" "catch 3"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 4"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 5"
+    continue_to_next_exception "main" "${catch_2_lineno}" "catch 6"
+    continue_to_breakpoint_in_main
+}
+
+# Now check that all of the command with a regexp that doesn't match,
+# don't trigger.
+with_test_prefix "all with invalid regexp" {
+    restart_for_test
+    setup_catchpoint "throw" "-r blahblah"
+    setup_catchpoint "rethrow" "-r woofwoof"
+    setup_catchpoint "catch" "-r miowmiow"
+
+    # Would like to use 'continue_to_breakpoint_in_main' here, if
+    # there wasn't a bug that requires a use of kfail.
+
+    mi_send_resuming_command "exec-continue" \
+	"exec-continue"
+    set testname "run until breakpoint in main"
+    gdb_expect {
+	-re "could not find minimal symbol for typeinfo address.*$mi_gdb_prompt$" {
+	    kfail "gdb/24541" "${testname}"
+	}
+	-re "\\*stopped,reason=\"breakpoint-hit\".*func=\"main\".*line=\"${main_lineno}\".*$mi_gdb_prompt$" {
+	    pass "${testname}"
+	}
+	timeout {
+	    fail "${testname} (timeout)"
+	}
+    }
+}
+
+# Now check that all of the commands with a regexp that does match,
+# still trigger.
+with_test_prefix "all with valid regexp" {
+    restart_for_test
+    setup_catchpoint "throw" "-r my_ex"
+    setup_catchpoint "rethrow" "-r _except"
+    setup_catchpoint "catch" "-r my_exception"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 1"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 1"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 2"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 2"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 1"
+    continue_to_next_exception "main" "${catch_2_lineno}" "catch 3"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 3"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 4"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 4"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 5"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 2"
+    continue_to_next_exception "main" "${catch_2_lineno}" "catch 6"
+    continue_to_breakpoint_in_main
+}
+
+# Check that the temporary switch works on its own.
+with_test_prefix "all with -t" {
+    restart_for_test
+    setup_catchpoint "throw" "-t"
+    setup_catchpoint "rethrow" "-t"
+    setup_catchpoint "catch" "-t"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 1"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 1"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 1"
+    continue_to_breakpoint_in_main
+}
+
+# Check that the temporary switch works when used with a regexp.
+restart_for_test
+with_test_prefix "all with -t and regexp" {
+    setup_catchpoint "throw" "-t -r my_ex"
+    setup_catchpoint "rethrow" "-t -r _except"
+    setup_catchpoint "catch" "-t -r my_exception"
+    continue_to_next_exception "bar" "${throw_1_lineno}" "throw 1"
+    continue_to_next_exception "foo" "${catch_1_lineno}" "catch 1"
+    continue_to_next_exception "foo" "${throw_2_lineno}" "rethrow 1"
+    continue_to_breakpoint_in_main
+}