gdb/mi: fix breakpoint script field output

The "script" field, output whenever information about a breakpoint with
commands is output, uses wrong MI syntax.

    $ ./gdb -nx -q --data-directory=data-directory -x script -i mi
    =thread-group-added,id="i1"
    =breakpoint-created,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x000000000000111d",func="main",file="test.c",fullname="/home/simark/build/binutils-gdb-one-target/gdb/test.c",line="3",thread-groups=["i1"],times="0",original-location="main"}
    =breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x000000000000111d",func="main",file="test.c",fullname="/home/simark/build/binutils-gdb-one-target/gdb/test.c",line="3",thread-groups=["i1"],times="0",script={"aaa","bbb","ccc"},original-location="main"}
    (gdb)
    -break-info
    ^done,BreakpointTable={nr_rows="1",nr_cols="6",hdr=[{width="7",alignment="-1",col_name="number",colhdr="Num"},{width="14",alignment="-1",col_name="type",colhdr="Type"},{width="4",alignment="-1",col_name="disp",colhdr="Disp"},{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},{width="18",alignment="-1",col_name="addr",colhdr="Address"},{width="40",alignment="2",col_name="what",colhdr="What"}],body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x000000000000111d",func="main",file="test.c",fullname="/home/simark/build/binutils-gdb-one-target/gdb/test.c",line="3",thread-groups=["i1"],times="0",script={"aaa","bbb","ccc"},original-location="main"}]}
    (gdb)

In both the =breakpoint-modified and -break-info output, we have:

     script={"aaa","bbb","ccc"}

According to the output syntax [1], curly braces means tuple, and a
tuple contains key=value pairs.  This looks like it should be a list,
but uses curly braces by mistake.  This would make more sense:

    script=["aaa","bbb","ccc"]

Fix it, keeping the backwards compatibility by introducing a new MI
version (MI4), in exactly the same way as was done when fixing
multi-locations breakpoint output in [2].

 - Add a fix_breakpoint_script_output uiout flag.  MI uiouts will use
   this flag if the version is >= 4.
 - Add a fix_breakpoint_script_output_globally variable and the
   -fix-breakpoint-script-output MI command to set it, if frontends want
   to use the fixed output for this without using the newer MI version.
 - When emitting the script field, use list instead of tuple, if we want
   the fixed output (depending on the two criteria above)
 -

[1] https://sourceware.org/gdb/onlinedocs/gdb/GDB_002fMI-Output-Syntax.html#GDB_002fMI-Output-Syntax
[2] b4be1b0648

Change-Id: I7113c6892832c8d6805badb06ce42496677e2242
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24285

gdb/NEWS

@@ -381,6 +381,20 @@ winheight
     option, which causes the new inferior to start without a
     connection.
 
+ ** The default version of the MI interpreter is now 4 (-i=mi4).
+
+ ** The "script" field in breakpoint output (which is syntactically
+    incorrect in MI 3 and below) has changed in MI 4 to become a list.
+    This affects the following commands and events:
+
+	- -break-insert
+	- -break-info
+	- =breakpoint-created
+	- =breakpoint-modified
+
+    The -fix-breakpoint-script-output command can be used to enable
+    this behavior with previous MI versions.
+
 * New targets
 
 GNU/Linux/LoongArch		loongarch*-*-linux*

gdb/breakpoint.c

@@ -6162,6 +6162,10 @@ output_thread_groups (struct ui_out *uiout,
     }
 }
 
+/* See breakpoint.h. */
+
+bool fix_breakpoint_script_output_globally = false;
+
 /* Print B to gdb_stdout.  If RAW_LOC, print raw breakpoint locations
    instead of going via breakpoint_ops::print_one.  This makes "maint
    info breakpoints" show the software breakpoint locations of
@@ -6458,7 +6462,19 @@ print_one_breakpoint_location (struct breakpoint *b,
   if (!part_of_multiple && l)
     {
       annotate_field (9);
-      ui_out_emit_tuple tuple_emitter (uiout, "script");
+
+      bool use_fixed_output =
+	(uiout->test_flags (fix_breakpoint_script_output)
+         || fix_breakpoint_script_output_globally);
+
+      gdb::optional<ui_out_emit_tuple> tuple_emitter;
+      gdb::optional<ui_out_emit_list> list_emitter;
+
+      if (use_fixed_output)
+	list_emitter.emplace (uiout, "script");
+      else
+	tuple_emitter.emplace (uiout, "script");
+
       print_command_lines (uiout, l, 4);
     }
 

gdb/breakpoint.h

@@ -1871,6 +1871,11 @@ extern cmd_list_element *commands_cmd_element;
 
 extern bool fix_multi_location_breakpoint_output_globally;
 
+/* Whether to use the fixed output when printing information about
+   commands attached to a breakpoint.  */
+
+extern bool fix_breakpoint_script_output_globally;
+
 /* Deal with "catch catch", "catch throw", and "catch rethrow" commands and
    the MI equivalents.  Sets up to catch events of type EX_EVENT.  When
    TEMPFLAG is true only the next matching event is caught after which the

gdb/doc/gdb.texinfo

@@ -30472,6 +30472,21 @@ The multiple locations are now placed in a @code{locations} field, whose value
 is a list.
 @end itemize
 
+@item
+@center 4
+@tab
+@center 13.1
+@tab
+
+@itemize
+@item
+The syntax of the "script" field in breakpoint output has changed in the
+responses to the @code{-break-insert} and @code{-break-info} commands, as
+well as the @code{=breakpoint-created} and @code{=breakpoint-modified}
+events.  The previous output was syntactically invalid.  The new output is
+a list.
+@end itemize
+
 @end multitable
 
 If your front end cannot yet migrate to a more recent version of the
@@ -30482,9 +30497,14 @@ available in those recent MI versions, using the following commands:
 
 @item -fix-multi-location-breakpoint-output
 Use the output for multi-location breakpoints which was introduced by
-MI 3, even when using MI versions 2 or 1.  This command has no
+MI 3, even when using MI versions below 3.  This command has no
 effect when using MI version 3 or later.
 
+@item -fix-breakpoint-script-output
+Use the output for the breakpoint "script" field which was introduced by
+MI 4, even when using MI versions below 4.  This command has no effect when
+using MI version 4 or later.
+
 @end table
 
 The best way to avoid unexpected changes in MI that might break your front
@@ -31647,14 +31667,14 @@ The corresponding @value{GDBN} command is @samp{dprintf}.
 4^done,bkpt=@{number="1",type="dprintf",disp="keep",enabled="y",
 addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
 fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
-times="0",script=@{"printf \"At foo entry\\n\"","continue"@},
+times="0",script=["printf \"At foo entry\\n\"","continue"],
 original-location="foo"@}
 (gdb)
 5-dprintf-insert 26 "arg=%d, g=%d\n" arg g
 5^done,bkpt=@{number="2",type="dprintf",disp="keep",enabled="y",
 addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
 fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
-times="0",script=@{"printf \"arg=%d, g=%d\\n\", arg, g","continue"@},
+times="0",script=["printf \"arg=%d, g=%d\\n\", arg, g","continue"],
 original-location="mi-dprintf.c:26"@}
 (gdb)
 @end smallexample

gdb/interps.h

@@ -178,6 +178,7 @@ extern void interpreter_completer (struct cmd_list_element *ignore,
 #define INTERP_MI1             "mi1"
 #define INTERP_MI2             "mi2"
 #define INTERP_MI3             "mi3"
+#define INTERP_MI4             "mi4"
 #define INTERP_MI		"mi"
 #define INTERP_TUI		"tui"
 #define INTERP_INSIGHT		"insight"

gdb/mi/mi-cmds.c

@@ -282,6 +282,8 @@ add_builtin_mi_commands ()
   add_mi_cmd_mi ("file-list-shared-libraries",
      mi_cmd_file_list_shared_libraries),
   add_mi_cmd_cli ("file-symbol-file", "symbol-file", 1);
+  add_mi_cmd_mi ("fix-breakpoint-script-output",
+		 mi_cmd_fix_breakpoint_script_output),
   add_mi_cmd_mi ("fix-multi-location-breakpoint-output",
 		 mi_cmd_fix_multi_location_breakpoint_output),
   add_mi_cmd_mi ("gdb-exit", mi_cmd_gdb_exit);

gdb/mi/mi-interp.c

@@ -1343,6 +1343,7 @@ _initialize_mi_interp ()
   interp_factory_register (INTERP_MI1, mi_interp_factory);
   interp_factory_register (INTERP_MI2, mi_interp_factory);
   interp_factory_register (INTERP_MI3, mi_interp_factory);
+  interp_factory_register (INTERP_MI4, mi_interp_factory);
   interp_factory_register (INTERP_MI, mi_interp_factory);
 
   gdb::observers::signal_received.attach (mi_on_signal_received, "mi-interp");

gdb/mi/mi-main.c

@@ -1865,7 +1865,8 @@ captured_mi_execute_command (struct ui_out *uiout, struct mi_parse *context)
 	if (current_interp_named_p (INTERP_MI)
 	    || current_interp_named_p (INTERP_MI1)
 	    || current_interp_named_p (INTERP_MI2)
-	    || current_interp_named_p (INTERP_MI3))
+	    || current_interp_named_p (INTERP_MI3)
+	    || current_interp_named_p (INTERP_MI4))
 	  {
 	    if (!running_result_record_printed)
 	      {
@@ -2709,6 +2710,14 @@ mi_cmd_fix_multi_location_breakpoint_output (const char *command, char **argv,
   fix_multi_location_breakpoint_output_globally = true;
 }
 
+/* See mi/mi-main.h.  */
+
+void
+mi_cmd_fix_breakpoint_script_output (const char *command, char **argv, int argc)
+{
+  fix_breakpoint_script_output_globally = true;
+}
+
 /* Implement the "-complete" command.  */
 
 void

gdb/mi/mi-main.h

@@ -71,4 +71,9 @@ extern void mi_execute_cli_command (const char *cmd, bool args_p,
 extern void mi_cmd_fix_multi_location_breakpoint_output (const char *command,
 							 char **argv, int argc);
 
+/* Implementation of -fix-breakpoint-script-output.  */
+
+extern void mi_cmd_fix_breakpoint_script_output (const char *command,
+						 char **argv, int argc);
+
 #endif /* MI_MI_MAIN_H */

gdb/mi/mi-out.c

@@ -288,8 +288,7 @@ mi_ui_out::version ()
 /* Constructor for an `mi_out_data' object.  */
 
 mi_ui_out::mi_ui_out (int mi_version)
-: ui_out (mi_version >= 3
-	  ? fix_multi_location_breakpoint_output : (ui_out_flag) 0),
+: ui_out (make_flags (mi_version)),
   m_suppress_field_separator (false),
   m_suppress_output (false),
   m_mi_version (mi_version)
@@ -307,7 +306,10 @@ mi_ui_out::~mi_ui_out ()
 mi_ui_out *
 mi_out_new (const char *mi_version)
 {
-  if (streq (mi_version, INTERP_MI3) ||  streq (mi_version, INTERP_MI))
+  if (streq (mi_version, INTERP_MI4) ||  streq (mi_version, INTERP_MI))
+    return new mi_ui_out (4);
+
+  if (streq (mi_version, INTERP_MI3))
     return new mi_ui_out (3);
 
   if (streq (mi_version, INTERP_MI2))

gdb/mi/mi-out.h

@@ -106,6 +106,25 @@ private:
      redirected.  */
   string_file *main_stream ();
 
+  /* Helper for the constructor, deduce ui_out_flags for the given
+     MI_VERSION.  */
+  static ui_out_flags make_flags (int mi_version)
+  {
+    ui_out_flags flags = 0;
+
+    /* In MI version 2 and below, multi-location breakpoints had a wrong
+       syntax.  It is fixed in version 3.  */
+    if (mi_version >= 3)
+      flags |= fix_multi_location_breakpoint_output;
+
+    /* In MI version 3 and below, the "script" field in breakpoint output
+       had a wrong syntax.  It is fixed in version 4.  */
+    if (mi_version >= 4)
+      flags |= fix_breakpoint_script_output;
+
+    return flags;
+  }
+
   bool m_suppress_field_separator;
   bool m_suppress_output;
   int m_mi_version;

gdb/testsuite/gdb.mi/mi-breakpoint-changed.exp

@@ -97,7 +97,7 @@ proc test_insert_delete_modify { } {
 	$test
     set test "dprintf marker, \"arg\" \""
     mi_gdb_test $test \
-	{.*=breakpoint-created,bkpt=\{number="6",type="dprintf".*,script=\{\"printf \\\"arg\\\" \\\"\"\}.*\}\r\n\^done} \
+	{.*=breakpoint-created,bkpt=\{number="6",type="dprintf".*,script=\[\"printf \\\"arg\\\" \\\"\"\].*\}\r\n\^done} \
 	$test
 
     # 2. when modifying condition

gdb/testsuite/gdb.mi/mi-breakpoint-script.c

@@ -0,0 +1,22 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2022 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/>.  */
+
+int
+main (void)
+{
+  return 0;
+}

gdb/testsuite/gdb.mi/mi-breakpoint-script.exp

@@ -0,0 +1,98 @@
+# Copyright 2022 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/>.
+
+# Tests the breakpoint script field, including the wrong syntax that GDB
+# emitted before version 13.1.
+
+load_lib mi-support.exp
+standard_testfile .c
+
+if {[gdb_compile "$srcdir/$subdir/$srcfile" $binfile executable {debug}] != "" } {
+    return -1
+}
+
+# Generate the regexp pattern used to match the breakpoint description emitted
+# in the various breakpoint command results/events.
+#
+# - EXPECT_FIXED_OUTPUT: If true, expect GDB to output the fixed output for the
+#   script field, else expect it to output the broken pre-mi4 format.
+
+proc make_pattern { expect_fixed_output } {
+    if $expect_fixed_output {
+	return "bkpt=\{number=\"${::decimal}\",type=\"breakpoint\",.*,script=\\\[\"abc\",\"def\"\\\],.*"
+    } else {
+	return "bkpt=\{number=\"${::decimal}\",type=\"breakpoint\",.*,script=\\\{\"abc\",\"def\"\\\},.*"
+    }
+}
+
+# Run the test with the following parameters:
+#
+# - MI_VERSION: the version of the MI interpreter to use (e.g. "2")
+# - USE_FIX_FLAG: Whether to issue the -fix-breakpoint-script-output
+#   command after starting GDB
+# - EXPECT_FIXED_OUTPUT: If true, expect GDB to output the fixed output for the
+#   script field, else expect it to output the broken pre-mi4 format.
+
+proc do_test { mi_version use_fix_flag expect_fixed_output } {
+    with_test_prefix "mi_version=${mi_version}" {
+	with_test_prefix "use_fix_flag=${use_fix_flag}" {
+	    save_vars { ::MIFLAGS } {
+		set ::MIFLAGS "-i=mi${mi_version}"
+
+		mi_clean_restart $::binfile
+	    }
+
+	    if $use_fix_flag {
+		mi_gdb_test "-fix-breakpoint-script-output" "\\^done" \
+		    "send -fix-multi-location-breakpoint-output"
+	    }
+
+            # Create a breakpoint.
+	    mi_gdb_test "-break-insert main" ".*" "add breakpoint on main"
+
+            set pattern [make_pattern $expect_fixed_output]
+
+            # Add commands.  Use the CLI command, so we can verify the
+            # =breakpoint-modified output.
+            mi_gdb_test "commands\nabc\ndef\nend" ".*=breakpoint-modified,$pattern\r\n\\^done" "add breakpoint commands"
+
+	    # Check the -break-info output.
+	    mi_gdb_test "-break-info" \
+		"\\^done,BreakpointTable=.*${pattern}" \
+		"-break-info"
+
+	    mi_gdb_exit
+	}
+    }
+}
+
+# Vanilla mi3
+do_test 3 0 0
+
+# mi3 with -fix-breakpoint-script-output
+do_test 3 1 1
+
+# Vanilla mi4
+do_test 4 0 1
+
+# mi4 with -fix-breakpoint-script-output
+do_test 4 1 1
+
+# Whatever MI version is currently the default one, vanilla
+do_test "" 0 1
+
+# Whatever MI version is currently the default one, with
+# -fix-breakpoint-script-output
+do_test "" 1 1

gdb/ui-out.h

@@ -55,7 +55,8 @@ enum ui_out_flag
   fix_multi_location_breakpoint_output = (1 << 1),
   /* This indicates that %pF should be disallowed in a printf format
      string.  */
-  disallow_ui_out_field = (1 << 2)
+  disallow_ui_out_field = (1 << 2),
+  fix_breakpoint_script_output = (1 << 3),
 };
 
 DEF_ENUM_FLAGS_TYPE (ui_out_flag, ui_out_flags);