Re: [PATCH 00/16] Add styling to the gdb CLI and TUI

[Eli Zaretskii <eliz@gnu.org>]

> From: Tom Tromey <tom@tromey.com>
> Cc: Tom Tromey <tom@tromey.com>,  gdb-patches@sourceware.org
> Date: Mon, 04 Mar 2019 10:40:46 -0700
> 
> >>>>> "Eli" == Eli Zaretskii <eliz@gnu.org> writes:
> 
> Eli> What do you think about the idea to add a convenience variable that
> Eli> would provide the GDB version?
> 
> Seems reasonable to me.

How about the patch below?  Is it okay to go in?  (Note that I took
this opportunity to clean up whitespace in top.c, I hope it's OK to do
that as part of unrelated code changes.)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ac61e65..f2915d0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2019-03-06  Eli Zaretskii  <eliz@gnu.org>
+
+	* NEWS: Announce $_gdb_version.
+
+	* top.c (init_gdb_version_var): New function.
+	(gdb_init): Call init_gdb_version_var.
+
 2019-03-06  Tom Tromey  <tromey@adacore.com>
 
 	* remote-sim.c (gdbsim_target_open): Use result of
diff --git a/gdb/NEWS b/gdb/NEWS
index cc7c35c..260e6cc 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,12 @@
 
 *** Changes since GDB 8.3
 
+* New built-in convenience variable $_gdb_version provides the GDB
+  version.  It is handy for conditionally using features available
+  only in or since specific GDB versions, in scripts that should work
+  error-free with many different versions, such as in system-wide init
+  files.
+
 *** Changes in GDB 8.3
 
 * GDB and GDBserver now support access to additional registers on
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 0380322..313a061 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,7 @@
+2019-03-06  Eli Zaretskii  <eliz@gnu.org>
+
+	* gdb.texinfo (Convenience Vars): Document $_gdb_version.
+
 2019-03-05  Simon Marchi  <simon.marchi@efficios.com>
 
 	* python.texi (Values From Inferior): Change synopsys of the
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f2028f8..9d15337 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -11197,7 +11197,7 @@
 @vindex $_tlb@r{, convenience variable}
 The variable @code{$_tlb} is automatically set when debugging
 applications running on MS-Windows in native mode or connected to
-gdbserver that supports the @code{qGetTIBAddr} request. 
+gdbserver that supports the @code{qGetTIBAddr} request.
 @xref{General Query Packets}.
 This variable contains the address of the thread information block.
 
@@ -11211,6 +11211,17 @@
 @item $_gthread
 The global number of the current thread.  @xref{global thread numbers}.
 
+@item $_gdb_version
+@vindex $_gdb_version@r{, convenience variable}
+The version of the running @value{GDBN}.  The value is an integer
+number that encodes the major and minor @value{GDBN} versions as
+@w{@code{@var{major}*100 + @var{minor}}}, so, e.g., @value{GDBN}
+version 9.10 will produce the value @code{910}.  Development snapshots
+and pretest versions have their minor version incremented by one;
+thus, @value{GDBN} pretest 9.11.90 will produce the value 912.  This
+variable allows you to write scripts that work with different versions
+of @value{GDBN} without errors caused by features unavailable in some
+of those versions.
 @end table
 
 @node Convenience Funs
diff --git a/gdb/top.c b/gdb/top.c
index 22e6f7e..97b349a 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -147,22 +147,22 @@ int server_command;
 
 /* Timeout limit for response from target.  */
 
-/* The default value has been changed many times over the years.  It 
-   was originally 5 seconds.  But that was thought to be a long time 
+/* The default value has been changed many times over the years.  It
+   was originally 5 seconds.  But that was thought to be a long time
    to sit and wait, so it was changed to 2 seconds.  That was thought
-   to be plenty unless the connection was going through some terminal 
+   to be plenty unless the connection was going through some terminal
    server or multiplexer or other form of hairy serial connection.
 
-   In mid-1996, remote_timeout was moved from remote.c to top.c and 
+   In mid-1996, remote_timeout was moved from remote.c to top.c and
    it began being used in other remote-* targets.  It appears that the
    default was changed to 20 seconds at that time, perhaps because the
    Renesas E7000 ICE didn't always respond in a timely manner.
 
    But if 5 seconds is a long time to sit and wait for retransmissions,
-   20 seconds is far worse.  This demonstrates the difficulty of using 
+   20 seconds is far worse.  This demonstrates the difficulty of using
    a single variable for all protocol timeouts.
 
-   As remote.c is used much more than remote-e7000.c, it was changed 
+   As remote.c is used much more than remote-e7000.c, it was changed
    back to 2 seconds in 1999.  */
 
 int remote_timeout = 2;
@@ -188,9 +188,9 @@ int (*deprecated_ui_loop_hook) (int);
 
 /* Called from print_frame_info to list the line we stopped in.  */
 
-void (*deprecated_print_frame_info_listing_hook) (struct symtab * s, 
+void (*deprecated_print_frame_info_listing_hook) (struct symtab * s,
 						  int line,
-						  int stopline, 
+						  int stopline,
 						  int noerror);
 /* Replaces most of query.  */
 
@@ -237,7 +237,7 @@ ptid_t (*deprecated_target_wait_hook) (ptid_t ptid,
 /* Used by UI as a wrapper around command execution.  May do various
    things like enabling/disabling buttons, etc...  */
 
-void (*deprecated_call_command_hook) (struct cmd_list_element * c, 
+void (*deprecated_call_command_hook) (struct cmd_list_element * c,
 				      const char *cmd, int from_tty);
 
 /* Called when the current thread changes.  Argument is thread id.  */
@@ -1339,8 +1339,9 @@ There is NO WARRANTY, to the extent permitted by law.");
 resources online at:\n    <http://www.gnu.org/software/gdb/documentation/>."));
   fprintf_filtered (stream, "\n\n");
   fprintf_filtered (stream, _("For help, type \"help\".\n"));
-  fprintf_filtered (stream, _("Type \"apropos word\" to search for \
-commands related to \"word\"."));
+  fprintf_filtered (stream,
+		    _("Type \"apropos word\" to search for commands \
+related to \"word\"."));
 }
 
 /* Print the details of GDB build-time configuration.  */
@@ -1608,7 +1609,7 @@ quit_force (int *exit_arg, int from_tty)
 
   undo_terminal_modifications_before_exit ();
 
-  /* An optional expression may be used to cause gdb to terminate with the 
+  /* An optional expression may be used to cause gdb to terminate with the
      value of that expression.  */
   if (exit_arg)
     exit_code = *exit_arg;
@@ -1998,11 +1999,21 @@ set_history_filename (const char *args,
      directories the file written will be the same as the one
      that was read.  */
   if (!IS_ABSOLUTE_PATH (history_filename))
-    history_filename = reconcat (history_filename, current_directory, "/", 
+    history_filename = reconcat (history_filename, current_directory, "/",
 				 history_filename, (char *) NULL);
 }
 
 static void
+init_gdb_version_var (void)
+{
+  struct internalvar *version_var = create_internalvar ("_gdb_version");
+  int vmajor = 0, vminor = 0, vrevision = 0;
+  sscanf (version, "%d.%d.%d", &vmajor, &vminor, &vrevision);
+  set_internalvar_integer (version_var,
+			   vmajor * 100 + vminor + (vrevision > 0));
+}
+
+static void
 init_main (void)
 {
   struct cmd_list_element *c;
@@ -2206,4 +2217,7 @@ gdb_init (char *argv0)
      prefix to be installed.  Keep things simple and just do final
      script initialization here.  */
   finish_ext_lang_initialization ();
+
+  /* Create $_gdb_version convenience variable.  */
+  init_gdb_version_var ();
 }