(Ada) Add gdb-mi support for stopping at start of exception handler.

Following my previous commit which add support for stopping at start of
exception handler, this commit adds required gdb-mi support for this
feature.

gdb/ChangeLog:

    * mi/mi-cmd-catch.c (mi_cmd_catch_handlers): New function.
    * mi/mi-cmds.c (mi_cmds): Add catch-handlers command.
    * mi/mi-cmds.h (mi_cmd_catch_handlers): Add external declaration.
    * NEWS: Document "-catch-handlers" command.

gdb/doc/ChangeLog:

    * gdb.texinfo (Ada Exception gdb/mi Catchpoints): Add
    documentation for new "-catch-handlers" command.

gdb/testsuite/ChangeLog:

    * gdb.ada/mi_catch_ex_hand.exp: New testcase.
    * gdb.ada/mi_catch_ex_hand/foo.adb: New file.

Tested on x86_64-linux.

gdb/NEWS

@@ -377,6 +377,10 @@ show disassembler-options
   List the shared libraries in the program.  This is
   equivalent to the CLI command "info shared".
 
+-catch-handlers
+  Catchpoints stopping the program when Ada exceptions are
+  handled.  This is equivalent to the CLI command "catch handlers".
+
 *** Changes in GDB 7.12
 
 * GDB and GDBserver now build with a C++ compiler by default.

gdb/doc/gdb.texinfo

@@ -28537,6 +28537,50 @@ times="0",original-location="__gnat_debug_raise_exception"@}
 (gdb)
 @end smallexample
 
+@subheading The @code{-catch-handlers} Command
+@findex -catch-handlers
+
+@subsubheading Synopsis
+
+@smallexample
+ -catch-handlers [ -c @var{condition}] [ -d ] [ -e @var{exception-name} ]
+    [ -t ]
+@end smallexample
+
+Add a catchpoint stopping when Ada exceptions are handled.
+By default, the command stops the program when any Ada exception
+gets handled.  But it is also possible, by using some of the
+optional parameters described below, to create more selective
+catchpoints.
+
+The possible optional parameters for this command are:
+
+@table @samp
+@item -c @var{condition}
+Make the catchpoint conditional on @var{condition}.
+@item -d
+Create a disabled catchpoint.
+@item -e @var{exception-name}
+Only stop when @var{exception-name} is handled.
+@item -t
+Create a temporary catchpoint.
+@end table
+
+@subsubheading @value{GDBN} Command
+
+The corresponding @value{GDBN} command is @samp{catch handlers}.
+
+@subsubheading Example
+
+@smallexample
+-catch-handlers -e Constraint_Error
+^done,bkptno="4",bkpt=@{number="4",type="breakpoint",disp="keep",
+enabled="y",addr="0x0000000000402f68",
+what="`Constraint_Error' Ada exception handlers",thread-groups=["i1"],
+times="0",original-location="__gnat_begin_handler"@}
+(gdb)
+@end smallexample
+
 @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 @node GDB/MI Program Context
 @section @sc{gdb/mi}  Program Context

gdb/mi/mi-cmd-catch.c

@@ -157,8 +157,76 @@ mi_cmd_catch_exception (const char *cmd, char *argv[], int argc)
   if (exception_name != NULL)
     exception_name = xstrdup (exception_name);
   create_ada_exception_catchpoint (gdbarch, ex_kind,
-				   exception_name, condition,
-				   temp, enabled, 0);
+				   exception_name,
+				   condition, temp, enabled, 0);
+}
+
+/* Handler for the -catch-handlers command.  */
+
+void
+mi_cmd_catch_handlers (const char *cmd, char *argv[], int argc)
+{
+  struct gdbarch *gdbarch = get_current_arch ();
+  std::string condition;
+  int enabled = 1;
+  char *exception_name = NULL;
+  int temp = 0;
+
+  int oind = 0;
+  char *oarg;
+
+  enum opt
+    {
+      OPT_CONDITION, OPT_DISABLED, OPT_EXCEPTION_NAME, OPT_TEMP
+    };
+  static const struct mi_opt opts[] =
+    {
+      { "c", OPT_CONDITION, 1},
+      { "d", OPT_DISABLED, 0 },
+      { "e", OPT_EXCEPTION_NAME, 1 },
+      { "t", OPT_TEMP, 0 },
+      { 0, 0, 0 }
+    };
+
+  for (;;)
+    {
+      int opt = mi_getopt ("-catch-handlers", argc, argv, opts,
+			   &oind, &oarg);
+
+      if (opt < 0)
+        break;
+
+      switch ((enum opt) opt)
+        {
+	case OPT_CONDITION:
+	  condition.assign (oarg);
+	  break;
+	case OPT_DISABLED:
+	  enabled = 0;
+	  break;
+	case OPT_EXCEPTION_NAME:
+	  exception_name = oarg;
+	  break;
+	case OPT_TEMP:
+	  temp = 1;
+	  break;
+        }
+    }
+
+  /* This command does not accept any argument.  Make sure the user
+     did not provide any.  */
+  if (oind != argc)
+    error (_("Invalid argument: %s"), argv[oind]);
+
+  scoped_restore restore_breakpoint_reporting
+    = setup_breakpoint_reporting ();
+  /* create_ada_exception_catchpoint needs EXCEPTION_NAME to be
+     xstrdup'ed, and will assume control of its lifetime.  */
+  if (exception_name != NULL)
+    exception_name = xstrdup (exception_name);
+  create_ada_exception_catchpoint (gdbarch, ada_catch_handlers,
+				   exception_name,
+				   condition, temp, enabled, 0);
 }
 
 /* Common path for the -catch-load and -catch-unload.  */

gdb/mi/mi-cmds.c

@@ -69,6 +69,8 @@ static struct mi_cmd mi_cmds[] =
                    &mi_suppress_notification.breakpoint),
   DEF_MI_CMD_MI_1 ("catch-exception", mi_cmd_catch_exception,
                    &mi_suppress_notification.breakpoint),
+  DEF_MI_CMD_MI_1 ("catch-handlers", mi_cmd_catch_handlers,
+                   &mi_suppress_notification.breakpoint),
   DEF_MI_CMD_MI_1 ("catch-load", mi_cmd_catch_load,
                    &mi_suppress_notification.breakpoint),
   DEF_MI_CMD_MI_1 ("catch-unload", mi_cmd_catch_unload,

gdb/mi/mi-cmds.h

@@ -41,6 +41,7 @@ extern mi_cmd_argv_ftype mi_cmd_break_passcount;
 extern mi_cmd_argv_ftype mi_cmd_break_watch;
 extern mi_cmd_argv_ftype mi_cmd_catch_assert;
 extern mi_cmd_argv_ftype mi_cmd_catch_exception;
+extern mi_cmd_argv_ftype mi_cmd_catch_handlers;
 extern mi_cmd_argv_ftype mi_cmd_catch_load;
 extern mi_cmd_argv_ftype mi_cmd_catch_unload;
 extern mi_cmd_argv_ftype mi_cmd_disassemble;

gdb/testsuite/gdb.ada/mi_catch_ex_hand.exp

@@ -0,0 +1,137 @@
+# Copyright 2011-2018 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/>.
+
+load_lib "ada.exp"
+
+standard_ada_testfile foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug additional_flags=-gnata ]] != "" } {
+  return -1
+}
+
+# A global variable used to simplify the maintenance of some of
+# the regular expressions below.
+set eol "\[\r\n\]+"
+
+# Before going any further, verify that we can insert exception
+# handlers catchpoints...  That way, we won't have to do this while
+# doing the actual GDB/MI testing.
+
+clean_restart ${testfile}
+
+if ![runto_main] then {
+   fail "cannot run to main, testcase aborted"
+   return 0
+}
+
+set msg "insert catchpoint on all Ada exceptions handlers"
+gdb_test_multiple "catch handlers" $msg {
+    -re "Catchpoint $decimal: all Ada exceptions handlers$eol$gdb_prompt $" {
+	pass $msg
+    }
+    -re "Your Ada runtime appears to be missing some debugging information.*\[\r\n\]+$gdb_prompt $" {
+	# If the runtime was not built with enough debug information,
+	# or if it was stripped, we can not test exception
+	# catchpoints.
+	unsupported $msg
+	return -1
+    }
+}
+
+# Now, we can start the GDB/MI testing itself...
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+gdb_exit
+if [mi_gdb_start] {
+    continue
+}
+
+#############################################
+# 1. Try catching all exceptions handlers.  #
+#############################################
+
+if ![mi_run_to_main] then {
+   fail "cannot run to main, testcase aborted"
+   return 0
+}
+
+mi_gdb_test "-catch-handlers" \
+            "\\^done,bkptno=\"$decimal\",bkpt={.*disp=\"keep\",enabled=\"y\",addr=\"$hex\",what=\"all Ada exceptions handlers\",.*}" \
+            "catch all exceptions handlers"
+
+# Continue to exception handler.
+
+proc continue_to_exception_handler { test line } {
+
+    global decimal
+
+    mi_send_resuming_command "exec-continue" "$test"
+
+    # Now MI stream output.
+    mi_expect_stop \
+	"breakpoint-hit\",disp=\"keep\",bkptno=\"$decimal\",exception-name=\"exception\"?" \
+	"foo" "" ".*" "$line" \
+	".*" \
+        $test
+}
+
+# We don't have the exception name info when stopping at the exception handlers
+# catchpoints so we use source line to check if the inferior stops at the
+# right location.
+
+set bp_ce_location [gdb_get_line_number "BREAK1" ${testdir}/foo.adb]
+continue_to_exception_handler \
+    "continue until CE handling caught by all-exceptions handlers catchpoint" \
+    "$bp_ce_location"
+
+set bp_pe_location [gdb_get_line_number "BREAK2" ${testdir}/foo.adb]
+continue_to_exception_handler \
+    "continue until PE handling caught by all-exceptions handlers catchpoint" \
+    "$bp_pe_location"
+
+##########################################################
+# 2. Try catching only some of the exceptions handlers.  #
+##########################################################
+
+# Here is the scenario:
+#  - Restart the debugger from scratch, runto_main
+#  - We'll catch only "Constraint_Error handlers"
+#  - continue, we should stop at the Constraint_Error exception handler
+#  - continue, we should not stop at the Program_Error exception handler
+#    but exit instead.
+
+if ![mi_run_to_main] then {
+   fail "cannot run to main, testcase aborted"
+   return 0
+}
+
+mi_gdb_test "-catch-handlers -e Constraint_Error" \
+            "\\^done,bkptno=\"$decimal\",bkpt={.*disp=\"keep\",enabled=\"y\",addr=\"$hex\",what=\"`Constraint_Error' Ada exception handlers\",.*}" \
+            "catch Constraint_Error"
+
+mi_execute_to "exec-continue" \
+              "breakpoint-hit\",disp=\"keep\",bkptno=\"$decimal\",exception-name=\"exception\"?" \
+              "foo" "" ".*" "$bp_ce_location" \
+              ".*" \
+              "continue to exception catchpoint hit"
+
+# Exit the inferior.
+mi_send_resuming_command "exec-continue" "continuing to inferior exit"
+mi_expect_stop "exited-normally" "" "" "" "" "" "exit normally"
+
+mi_gdb_exit
+return 0

gdb/testsuite/gdb.ada/mi_catch_ex_hand/foo.adb

@@ -0,0 +1,33 @@
+--  Copyright 2007-2018 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/>.
+
+procedure Foo is
+begin
+
+   begin
+      raise Constraint_Error;
+   exception
+      when Constraint_Error => -- BREAK1
+         null;
+   end;
+
+   begin
+      raise Program_Error;
+   exception
+      when Program_Error => -- BREAK2
+         null;
+   end;
+
+end Foo;