diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index a39ea22604..87bacd131c 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -51,6 +51,7 @@
 #include "cli/cli-cmds.h"
 #include "cli/cli-style.h"
 #include "cli/cli-utils.h"
+#include "cli/cli-style.h"
 
 #include "extension.h"
 #include "gdbsupport/pathstuff.h"
@@ -231,6 +232,7 @@ with_command_1 (const char *set_cmd_prefix,
     nested_cmd = repeat_previous ();
 
   cmd_list_element *set_cmd = lookup_cmd (&args, setlist, set_cmd_prefix,
+					  nullptr,
 					  /*allow_unknown=*/ 0,
 					  /*ignore_help_classes=*/ 1);
   gdb_assert (set_cmd != nullptr);
@@ -325,6 +327,146 @@ with_command_completer (struct cmd_list_element *ignore,
   with_command_completer_1 ("set ", tracker,  text);
 }
 
+/* Completer for the "set|show leading-args" commands.  */
+
+static void
+leading_args_cmd_completer (struct cmd_list_element *ignore,
+			    completion_tracker &tracker,
+			    const char *text, const char *word)
+{
+  tracker.set_use_custom_word_point (true);
+
+  complete_nested_command_line (tracker, text);
+}
+
+/* Look up the contents of TEXT as a command usable with leading args.
+   Throws an error if no such command is found.
+   Return the found command and advances TEXT past the found command.
+   If the found command is a postfix command, set *PREFIX_CMD to its prefix command.  */
+
+static struct cmd_list_element *
+lookup_cmd_for_leading_args (const char **text,
+			     struct cmd_list_element **prefix_cmd)
+{
+  const char *orig_text = *text;
+  struct cmd_list_element *lcmd, *alias, *cmd;
+
+  if (*text == nullptr || skip_spaces (*text) == nullptr)
+    error (_("COMMAND missing."));
+
+  /* We first use lookup_cmd to verify TEXT unambiguously identifies
+     a command.  */
+  lcmd = lookup_cmd (text, cmdlist, "", NULL,
+		     /*allow_unknown=*/ 0,
+		     /*ignore_help_classes=*/ 1);
+
+  /* Note that we accept leading args for prefix commands,
+     as a prefix command can also be a valid usable
+     command accepting some arguments.
+     For example, "thread apply" applies a command to a
+     list of thread ids, and is also the prefix command for
+     thread apply all.  */
+
+  /* We have an unambiguous command for which leading args
+     can be specified.  What remains after having fond LCMD
+     is either spaces, or the leading args character.  */
+
+  /* We then use lookup_cmd_composition to detect if the user
+     has specified an alias, and find the possible prefix_cmd
+     of cmd.  */
+  lookup_cmd_composition
+    (std::string (orig_text, *text - orig_text).c_str (),
+     &alias, prefix_cmd, &cmd);
+  gdb_assert (cmd != nullptr);
+  gdb_assert (cmd == lcmd);
+  if (alias != nullptr)
+    cmd = alias;
+
+  return cmd;
+}
+
+/* Implementation of the "set leading-args" command.  */
+
+static void
+set_leading_args_command (const char *arg, int from_tty)
+{
+  struct cmd_list_element *prefix_cmd;
+  struct cmd_list_element *cmd = lookup_cmd_for_leading_args (&arg, &prefix_cmd);
+
+  const char *leading_args = skip_spaces (arg);
+
+  if (*leading_args == '\0')
+    leading_args = nullptr;
+
+  if (cmd->leading_args)
+    xfree ((char *) cmd->leading_args);
+  if (leading_args == nullptr)
+    cmd->leading_args = nullptr;
+  else
+    cmd->leading_args = xstrdup (leading_args);
+}
+
+/* Print a message showing C's name and its leading args or <no leading args>
+   if C has no leading args.
+   If SILENT_FOR_NO_LEADING_ARGS, does nothing if C has no leading args.  */
+
+static void
+show_leading_args (struct cmd_list_element *c,
+		   const char *prefix,
+		   bool silent_for_no_leading_args)
+{
+  if (c->leading_args != nullptr || !silent_for_no_leading_args)
+    {
+      fputs_filtered ("leading-args ", gdb_stdout);
+      fprintf_styled (gdb_stdout, title_style.style (),
+		      "%s%s",
+		      prefix == nullptr ? "" : prefix, c->name);
+      fprintf_filtered (gdb_stdout, " = %s\n",
+			c->leading_args == nullptr
+			? "<no leading args>" : c->leading_args);
+    }
+}
+
+/* Recursively traverse COMMANDLIST and prints a message showing
+   the leading-args of the commands that have non-null leading args.
+   PREFIX is the prefix that led to COMMANDLIST.  */
+
+static void
+show_leading_args_command_1 (struct cmd_list_element *commandlist,
+			     const char *prefix)
+{
+  /* Walk through the commands.  */
+  for (cmd_list_element *c = commandlist; c; c = c->next)
+    {
+      show_leading_args (c, prefix, true);
+      /* If C has subcommands, recursively search if its subcommands
+	 have leading args.
+	 Do not recurse for abbreviations to avoid duplicates
+	 in the output.  */
+      if (c->prefixlist != NULL && !c->abbrev_flag)
+	show_leading_args_command_1 (*c->prefixlist, c->prefixname);
+    }
+}
+
+/* Implementation of the "show leading-args" command.  */
+
+static void
+show_leading_args_command (const char *arg, int from_tty)
+{
+  if (skip_spaces (arg) != nullptr)
+    {
+      struct cmd_list_element *prefix_cmd;
+      struct cmd_list_element *c = lookup_cmd_for_leading_args (&arg,
+								&prefix_cmd);
+
+      show_leading_args (c,
+			 prefix_cmd == nullptr ? "" : prefix_cmd->prefixname,
+			 false);
+    }
+  else
+    show_leading_args_command_1 (cmdlist, "");
+}
+
 
 /* Provide documentation on command or list given by COMMAND.  FROM_TTY
    is ignored.  */
@@ -1543,7 +1685,7 @@ show_user (const char *args, int from_tty)
     {
       const char *comname = args;
 
-      c = lookup_cmd (&comname, cmdlist, "", 0, 1);
+      c = lookup_cmd (&comname, cmdlist, "", NULL, 0, 1);
       if (!cli_user_command_p (c))
 	error (_("Not a user command."));
       show_user_1 (c, "", args, gdb_stdout);
@@ -1575,6 +1717,71 @@ apropos_command (const char *arg, int from_tty)
   apropos_cmd (gdb_stdout, cmdlist, verbose, pattern, "");
 }
 
+/* The options for the "alias" command.  */
+
+struct alias_opts
+{
+  /* For "-a".  */
+  bool abbrev_flag = 0;
+};
+
+static const gdb::option::option_def alias_option_defs[] = {
+
+  gdb::option::flag_option_def<alias_opts> {
+    "a",
+    [] (alias_opts *opts) { return &opts->abbrev_flag; },
+    N_("Specify that ALIAS is an abbreviation of COMMAND.\n\
+Abbreviations are not shown in command lists displayed by the 'help' command."),
+  },
+
+};
+
+/* Create an option_def_group for the "alias" options, with
+   A_OPTS as context.  */
+
+static inline gdb::option::option_def_group
+make_alias_options_def_group (alias_opts *a_opts)
+{
+  return {{alias_option_defs}, a_opts};
+}
+
+/* Completer for the "alias_command".  */
+
+static void
+alias_command_completer (struct cmd_list_element *ignore,
+			 completion_tracker &tracker,
+			 const char *text, const char *word)
+{
+  const auto grp = make_alias_options_def_group (nullptr);
+
+  tracker.set_use_custom_word_point (true);
+
+  if (gdb::option::complete_options
+      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, grp))
+    return;
+
+  const char *delim = strstr (text, "=");
+
+  /* If we're past the "=" delimiter, complete the
+     "alias ALIAS = COMMAND [LEADING-ARGS...]" as if the user is
+     typing COMMAND LEADING-ARGS...  */
+  if (delim != text
+      && delim != nullptr
+      && isspace (delim[-1])
+      && (isspace (delim[1]) || delim[1] == '\0'))
+    {
+      std::string new_text = std::string (delim + 1);
+
+      tracker.advance_custom_word_point_by (delim + 1 - text);
+      complete_nested_command_line (tracker, new_text.c_str ());
+      return;
+    }
+
+  /* We're not yet past the "=" delimiter.  Complete a command, as
+     the user might type an alias following a prefix command.  */
+  complete_nested_command_line (tracker, text);
+}
+
 /* Subroutine of alias_command to simplify it.
    Return the first N elements of ARGV flattened back to a string
    with a space separating each element.
@@ -1609,7 +1816,7 @@ valid_command_p (const char *command)
 {
   struct cmd_list_element *c;
 
-  c = lookup_cmd_1 (& command, cmdlist, NULL, 1);
+  c = lookup_cmd_1 (& command, cmdlist, NULL, NULL, 1);
 
   if (c == NULL || c == (struct cmd_list_element *) -1)
     return false;
@@ -1627,7 +1834,7 @@ valid_command_p (const char *command)
 static void
 alias_usage_error (void)
 {
-  error (_("Usage: alias [-a] [--] ALIAS = COMMAND"));
+  error (_("Usage: alias [-a] [--] ALIAS = COMMAND [LEADING-ARGS...]"));
 }
 
 /* Make an alias of an existing command.  */
@@ -1635,8 +1842,13 @@ alias_usage_error (void)
 static void
 alias_command (const char *args, int from_tty)
 {
+  alias_opts a_opts;
+
+  auto grp = make_alias_options_def_group (&a_opts);
+  gdb::option::process_options
+    (&args, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, grp);
+
   int i, alias_argc, command_argc;
-  int abbrev_flag = 0;
   const char *equals;
   const char *alias, *command;
 
@@ -1647,24 +1859,18 @@ alias_command (const char *args, int from_tty)
   std::string args2 (args, equals - args);
 
   gdb_argv built_alias_argv (args2.c_str ());
-  gdb_argv command_argv (equals + 1);
+
+  const char *leading_args = equals + 1;
+  struct cmd_list_element *c_command_prefix;
+
+  lookup_cmd_for_leading_args (&leading_args, &c_command_prefix);
+  std::string command_argv_str (equals + 1,
+				leading_args == nullptr
+				? strlen (equals + 1)
+				: leading_args - equals - 1);
+  gdb_argv command_argv (command_argv_str.c_str ());
 
   char **alias_argv = built_alias_argv.get ();
-  while (alias_argv[0] != NULL)
-    {
-      if (strcmp (alias_argv[0], "-a") == 0)
-	{
-	  ++alias_argv;
-	  abbrev_flag = 1;
-	}
-      else if (strcmp (alias_argv[0], "--") == 0)
-	{
-	  ++alias_argv;
-	  break;
-	}
-      else
-	break;
-    }
 
   if (alias_argv[0] == NULL || command_argv[0] == NULL
       || *alias_argv[0] == '\0' || *command_argv[0] == '\0')
@@ -1699,6 +1905,8 @@ alias_command (const char *args, int from_tty)
   if (valid_command_p (alias))
     error (_("Alias already exists: %s"), alias);
 
+  struct cmd_list_element *alias_cmd;
+
   /* If ALIAS is one word, it is an alias for the entire COMMAND.
      Example: alias spe = set print elements
 
@@ -1711,8 +1919,8 @@ alias_command (const char *args, int from_tty)
   if (alias_argc == 1)
     {
       /* add_cmd requires *we* allocate space for name, hence the xstrdup.  */
-      add_com_alias (xstrdup (alias_argv[0]), command, class_alias,
-		     abbrev_flag);
+      alias_cmd = add_com_alias (xstrdup (alias_argv[0]), command, class_alias,
+				 a_opts.abbrev_flag);
     }
   else
     {
@@ -1732,19 +1940,30 @@ alias_command (const char *args, int from_tty)
       alias_prefix = alias_prefix_string.c_str ();
       command_prefix = command_prefix_string.c_str ();
 
-      c_command = lookup_cmd_1 (& command_prefix, cmdlist, NULL, 1);
+      c_command = lookup_cmd_1 (& command_prefix, cmdlist, NULL, NULL, 1);
       /* We've already tried to look up COMMAND.  */
       gdb_assert (c_command != NULL
 		  && c_command != (struct cmd_list_element *) -1);
       gdb_assert (c_command->prefixlist != NULL);
-      c_alias = lookup_cmd_1 (& alias_prefix, cmdlist, NULL, 1);
+      c_alias = lookup_cmd_1 (& alias_prefix, cmdlist, NULL, NULL, 1);
       if (c_alias != c_command)
 	error (_("ALIAS and COMMAND prefixes do not match."));
 
       /* add_cmd requires *we* allocate space for name, hence the xstrdup.  */
-      add_alias_cmd (xstrdup (alias_argv[alias_argc - 1]),
-		     command_argv[command_argc - 1],
-		     class_alias, abbrev_flag, c_command->prefixlist);
+      alias_cmd = add_alias_cmd (xstrdup (alias_argv[alias_argc - 1]),
+				 command_argv[command_argc - 1],
+				 class_alias, a_opts.abbrev_flag,
+				 c_command->prefixlist);
+    }
+
+  gdb_assert (alias_cmd);
+  gdb_assert (alias_cmd->leading_args == nullptr);
+  if (leading_args != nullptr)
+    {
+      leading_args = skip_spaces (leading_args);
+
+      if (*leading_args != '\0')
+	alias_cmd->leading_args = xstrdup (leading_args);
     }
 }
 
@@ -2059,6 +2278,26 @@ You can supply a command number to start with, or a `+' to start after\n\
 the previous command number shown."),
 	   &showlist);
 
+  c = add_cmd ("leading-args", class_support, set_leading_args_command, _("\
+Set or clear leading args automatically prepended to a command or alias.\n\
+Usage: set leading-args COMMAND [LEADING-ARGS...]\n\
+Set or clear the leading arguments automatically prepended\n\
+to the arguments the user provides when COMMAND is run.\n\
+Note that COMMAND can be an alias.  Commands and their aliases\n\
+do not share their leading arguments, so you can specify different\n\
+leading arguments for a command and for each of its aliases.\n\
+Without the [= LEADING-ARGS...], clears COMMAND leading arguments."),
+	   &setlist);
+  set_cmd_completer_handle_brkchars (c, leading_args_cmd_completer);
+
+  c = add_cmd ("leading-args", class_support, show_leading_args_command, _("\
+Show the leading args of a command, or of all commands.\n\
+Usage: show leading-args [COMMAND]\n\
+Show the leading args of COMMAND.  Without COMMAND, show the leading args\n\
+of all commands."),
+	   &showlist);
+  set_cmd_completer_handle_brkchars (c, leading_args_cmd_completer);
+
   add_cmd ("version", no_set_class, show_version,
 	   _("Show what version of GDB this is."), &showlist);
 
@@ -2210,19 +2449,37 @@ When 'on', each command is displayed as it is executed."),
 			   NULL,
 			   &setlist, &showlist);
 
-  c = add_com ("alias", class_support, alias_command, _("\
+  const auto alias_opts = make_alias_options_def_group (nullptr);
+
+  static std::string alias_help
+    = gdb::option::build_help (_("\
 Define a new command that is an alias of an existing command.\n\
-Usage: alias [-a] [--] ALIAS = COMMAND\n\
+Usage: alias [-a] [--] ALIAS = COMMAND [LEADING-ARGS...]\n\
 ALIAS is the name of the alias command to create.\n\
 COMMAND is the command being aliased to.\n\
-If \"-a\" is specified, the command is an abbreviation,\n\
-and will not appear in help command list output.\n\
+\n\
+Options:\n\
+%OPTIONS%\
+You can optionally provide LEADING-ARGS to define at the same time\n\
+ALIAS and its leading args.  This is the equivalent of:\n\
+  alias ALIAS = COMMAND\n\
+  set leading-args ALIAS LEADING-ARGS...\n\
 \n\
 Examples:\n\
 Make \"spe\" an alias of \"set print elements\":\n\
-  alias spe = set print elements\n\
+  alias spe set print elements\n\
 Make \"elms\" an alias of \"elements\" in the \"set print\" command:\n\
-  alias -a set print elms = set print elements"));
+  alias -a set print elms set print elements\n\
+Make \"btf\" an alias of \"backtrace -full -past-entry -past-main\" :\n\
+  alias btf = backtrace -full -past-entry -past-main\n\
+Make \"wLapPeu\" an alias of 2 nested \"with\":\n\
+  alias wLapPeu = with language pascal -- with print elements unlimited --"),
+			       alias_opts);
+
+  c = add_com ("alias", class_support, alias_command,
+	       alias_help.c_str ());
+
+  set_cmd_completer_handle_brkchars (c, alias_command_completer);
 
   const char *source_help_text = xstrprintf (_("\
 Read commands from a file named FILE.\n\
diff --git a/gdb/cli/cli-decode.c b/gdb/cli/cli-decode.c
index debffbc0f7..b6c87180d9 100644
--- a/gdb/cli/cli-decode.c
+++ b/gdb/cli/cli-decode.c
@@ -343,7 +343,7 @@ add_alias_cmd (const char *name, const char *oldname,
   struct cmd_list_element *old;
 
   tmp = oldname;
-  old = lookup_cmd (&tmp, *list, "", 1, 1);
+  old = lookup_cmd (&tmp, *list, "", NULL, 1, 1);
 
   return add_alias_cmd (name, old, theclass, abbrev_flag, list);
 }
@@ -1045,6 +1045,7 @@ void
 help_cmd (const char *command, struct ui_file *stream)
 {
   struct cmd_list_element *c;
+  const char *initial_command = command;
 
   if (!command)
     {
@@ -1058,7 +1059,7 @@ help_cmd (const char *command, struct ui_file *stream)
       return;
     }
 
-  c = lookup_cmd (&command, cmdlist, "", 0, 0);
+  c = lookup_cmd (&command, cmdlist, "", NULL, 0, 0);
 
   if (c == 0)
     return;
@@ -1078,6 +1079,41 @@ help_cmd (const char *command, struct ui_file *stream)
   fputs_filtered (c->doc, stream);
   fputs_filtered ("\n", stream);
 
+  if (c->func != nullptr)
+    {
+      /* Print the leading args of the command if it has some.
+	 Use lookup_cmd_composition to find if help was requested for
+	 an alias.  In this case, rather print the alias leading_args.  */
+
+      struct cmd_list_element *alias, *prefix_cmd, *cmd;
+      const char *name, *leading_args;
+
+      lookup_cmd_composition (initial_command,
+			      &alias, &prefix_cmd, &cmd);
+      gdb_assert (cmd != nullptr);
+      gdb_assert (cmd == c);
+
+      if (alias == nullptr)
+	{
+	  name = c->name;
+	  leading_args = c->leading_args;
+	}
+      else
+	{
+	  name = alias->name;
+	  leading_args = alias->leading_args;
+	}
+      if (leading_args != nullptr)
+	{
+	  fputs_filtered ("leading-args ", stream);
+	  fprintf_styled (stream, title_style.style (),
+			  "%s%s",
+			  prefix_cmd == nullptr ? "" : prefix_cmd->prefixname,
+			  name);
+	  fprintf_filtered (stream, " = %s\n", leading_args);
+	}
+    }
+
   if (c->prefixlist == 0 && c->func != NULL)
     return;
   fprintf_filtered (stream, "\n");
@@ -1271,6 +1307,13 @@ print_help_for_command (struct cmd_list_element *c, const char *prefix,
   fputs_filtered (" -- ", stream);
   print_doc_line (stream, c->doc, false);
   fputs_filtered ("\n", stream);
+  if (c->leading_args != nullptr)
+    {
+      fputs_filtered ("  leading-args ", stream);
+      fprintf_styled (stream, title_style.style (),
+		      "%s%s", prefix, c->name);
+      fprintf_filtered (stream, " = %s\n", c->leading_args);
+    }
 
   if (recurse
       && c->prefixlist != 0
@@ -1418,8 +1461,12 @@ valid_user_defined_cmd_name_p (const char *name)
    the list in which there are ambiguous choices (and *TEXT will be set to
    the ambiguous text string).
 
+   if LEADING_ARGS is not null and the found command has leading args defined,
+   then *LEADING_ARGS points at these leading args.
+
    If the located command was an abbreviation, this routine returns the base
-   command of the abbreviation.
+   command of the abbreviation.  Note that *LEADING_ARGS will point at the
+   leading args defined for the alias.
 
    It does no error reporting whatsoever; control will always return
    to the superior routine.
@@ -1446,11 +1493,13 @@ valid_user_defined_cmd_name_p (const char *name)
 
 struct cmd_list_element *
 lookup_cmd_1 (const char **text, struct cmd_list_element *clist,
-	      struct cmd_list_element **result_list, int ignore_help_classes)
+	      struct cmd_list_element **result_list, const char **leading_args,
+	      int ignore_help_classes)
 {
   char *command;
   int len, nfound;
   struct cmd_list_element *found, *c;
+  bool found_alias = false;
   const char *line = *text;
 
   while (**text == ' ' || **text == '\t')
@@ -1486,6 +1535,8 @@ lookup_cmd_1 (const char **text, struct cmd_list_element *clist,
 	/* Will be modified in calling routine
 	   if we know what the prefix command is.  */
 	*result_list = 0;
+      if (leading_args != NULL)
+	*leading_args = nullptr;
       return CMD_LIST_AMBIGUOUS;	/* Ambiguous.  */
     }
 
@@ -1501,22 +1552,30 @@ lookup_cmd_1 (const char **text, struct cmd_list_element *clist,
        are warning about the alias, we may also warn about the command
        itself and we will adjust the appropriate DEPRECATED_WARN_USER
        flags.  */
-      
+
       if (found->deprecated_warn_user)
 	deprecated_cmd_warning (line);
+
+      /* Return the leading_args of the alias, not the leading_args
+	 of the command it is pointing to.  */
+      if (leading_args != NULL)
+	*leading_args = found->leading_args;
       found = found->cmd_pointer;
+      found_alias = true;
     }
   /* If we found a prefix command, keep looking.  */
 
   if (found->prefixlist)
     {
       c = lookup_cmd_1 (text, *found->prefixlist, result_list,
-			ignore_help_classes);
+			leading_args, ignore_help_classes);
       if (!c)
 	{
 	  /* Didn't find anything; this is as far as we got.  */
 	  if (result_list != NULL)
 	    *result_list = clist;
+	  if (!found_alias && leading_args != NULL)
+	    *leading_args = found->leading_args;
 	  return found;
 	}
       else if (c == CMD_LIST_AMBIGUOUS)
@@ -1531,6 +1590,9 @@ lookup_cmd_1 (const char **text, struct cmd_list_element *clist,
 	         at the top of this function to clarify what is
 	         supposed to be going on.  */
 	      *result_list = found;
+	  /* For ambiguous commands, do not return any leading_args args.  */
+	  if (leading_args != nullptr)
+	    *leading_args = nullptr;
 	  return c;
 	}
       else
@@ -1543,6 +1605,8 @@ lookup_cmd_1 (const char **text, struct cmd_list_element *clist,
     {
       if (result_list != NULL)
 	*result_list = clist;
+      if (!found_alias && leading_args != NULL)
+	*leading_args = found->leading_args;
       return found;
     }
 }
@@ -1562,21 +1626,28 @@ undef_cmd_error (const char *cmdtype, const char *q)
 
 /* Look up the contents of *LINE as a command in the command list LIST.
    LIST is a chain of struct cmd_list_element's.
-   If it is found, return the struct cmd_list_element for that command
-   and update *LINE to point after the command name, at the first argument.
+   If it is found, return the struct cmd_list_element for that command,
+   update *LINE to point after the command name, at the first argument
+   and update *LEADING_ARGS (if LEADING_ARGS is not null) to point at
+   the leading args to prepend to the user provided args when running
+   the command.
+   Note that if the found cmd_list_element is found via an alias,
+   the leading args of the alias are returned.
+
    If not found, call error if ALLOW_UNKNOWN is zero
    otherwise (or if error returns) return zero.
    Call error if specified command is ambiguous,
    unless ALLOW_UNKNOWN is negative.
    CMDTYPE precedes the word "command" in the error message.
 
-   If INGNORE_HELP_CLASSES is nonzero, ignore any command list
+   If IGNORE_HELP_CLASSES is nonzero, ignore any command list
    elements which are actually help classes rather than commands (i.e.
    the function field of the struct cmd_list_element is 0).  */
 
 struct cmd_list_element *
 lookup_cmd (const char **line, struct cmd_list_element *list,
 	    const char *cmdtype,
+	    const char **leading_args,
 	    int allow_unknown, int ignore_help_classes)
 {
   struct cmd_list_element *last_list = 0;
@@ -1588,7 +1659,7 @@ lookup_cmd (const char **line, struct cmd_list_element *list,
   if (!*line)
     error (_("Lack of needed %scommand"), cmdtype);
 
-  c = lookup_cmd_1 (line, list, &last_list, ignore_help_classes);
+  c = lookup_cmd_1 (line, list, &last_list, leading_args, ignore_help_classes);
 
   if (!c)
     {
diff --git a/gdb/cli/cli-decode.h b/gdb/cli/cli-decode.h
index 2ec4a97d81..b02076191f 100644
--- a/gdb/cli/cli-decode.h
+++ b/gdb/cli/cli-decode.h
@@ -69,6 +69,8 @@ struct cmd_list_element
     {
       if (doc && doc_allocated)
 	xfree ((char *) doc);
+      if (leading_args)
+	xfree ((char *) leading_args);
     }
 
     DISABLE_COPY_AND_ASSIGN (cmd_list_element);
@@ -176,6 +178,10 @@ struct cmd_list_element
     /* Hook for another command to be executed after this command.  */
     struct cmd_list_element *hook_post = nullptr;
 
+    /* Leading arguments to automatically prepend to the user
+       provided arguments when running this command or alias.  */
+    const char *leading_args = nullptr;
+
     /* Nonzero identifies a prefix command.  For them, the address
        of the variable containing the list of subcommands.  */
     struct cmd_list_element **prefixlist = nullptr;
diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index 3137955265..959c527ee0 100644
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -970,7 +970,7 @@ process_next_line (const char *p, struct command_line **command,
       /* Resolve command abbreviations (e.g. 'ws' for 'while-stepping').  */
       const char *cmd_name = p;
       struct cmd_list_element *cmd
-	= lookup_cmd_1 (&cmd_name, cmdlist, NULL, 1);
+	= lookup_cmd_1 (&cmd_name, cmdlist, NULL, NULL, 1);
       cmd_name = skip_spaces (cmd_name);
       bool inline_cmd = *cmd_name != '\0';
 
@@ -1327,7 +1327,7 @@ validate_comname (const char **comname)
       std::string prefix (*comname, last_word - 1);
       const char *tem = prefix.c_str ();
 
-      c = lookup_cmd (&tem, cmdlist, "", 0, 1);
+      c = lookup_cmd (&tem, cmdlist, "", NULL, 0, 1);
       if (c->prefixlist == NULL)
 	error (_("\"%s\" is not a prefix command."), prefix.c_str ());
 
@@ -1383,7 +1383,7 @@ do_define_command (const char *comname, int from_tty,
 
   /* Look it up, and verify that we got an exact match.  */
   tem = comname;
-  c = lookup_cmd (&tem, *list, "", -1, 1);
+  c = lookup_cmd (&tem, *list, "", NULL, -1, 1);
   if (c && strcmp (comname, c->name) != 0)
     c = 0;
 
@@ -1418,7 +1418,7 @@ do_define_command (const char *comname, int from_tty,
     {
       /* Look up cmd it hooks, and verify that we got an exact match.  */
       tem = comname + hook_name_size;
-      hookc = lookup_cmd (&tem, *list, "", -1, 0);
+      hookc = lookup_cmd (&tem, *list, "", NULL, -1, 0);
       if (hookc && strcmp (comname + hook_name_size, hookc->name) != 0)
 	hookc = 0;
       if (!hookc && commands == nullptr)
@@ -1487,7 +1487,7 @@ document_command (const char *comname, int from_tty)
   list = validate_comname (&comname);
 
   tem = comname;
-  c = lookup_cmd (&tem, *list, "", 0, 1);
+  c = lookup_cmd (&tem, *list, "", NULL, 0, 1);
 
   if (c->theclass != class_user)
     error (_("Command \"%s\" is built-in."), comfull);
diff --git a/gdb/command.h b/gdb/command.h
index cf190ef649..044e3319d4 100644
--- a/gdb/command.h
+++ b/gdb/command.h
@@ -244,11 +244,13 @@ extern enum cmd_types cmd_type (struct cmd_list_element *cmd);
 extern struct cmd_list_element *lookup_cmd (const char **,
 					    struct cmd_list_element *,
 					    const char *,
+					    const char **,
 					    int, int);
 
 extern struct cmd_list_element *lookup_cmd_1 (const char **,
 					      struct cmd_list_element *,
 					      struct cmd_list_element **,
+					      const char **,
 					      int);
 
 extern struct cmd_list_element *deprecate_cmd (struct cmd_list_element *,
diff --git a/gdb/completer.c b/gdb/completer.c
index 07facfb012..b88bdbdeca 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -1341,7 +1341,7 @@ complete_line_internal_1 (completion_tracker &tracker,
     }
   else
     {
-      c = lookup_cmd_1 (&p, cmdlist, &result_list, ignore_help_classes);
+      c = lookup_cmd_1 (&p, cmdlist, &result_list, NULL, ignore_help_classes);
     }
 
   /* Move p up to the next interesting thing.  */
diff --git a/gdb/guile/scm-cmd.c b/gdb/guile/scm-cmd.c
index f2fa40e453..8cf70f6e52 100644
--- a/gdb/guile/scm-cmd.c
+++ b/gdb/guile/scm-cmd.c
@@ -515,7 +515,7 @@ gdbscm_parse_command_name (const char *name,
   prefix_text[i + 1] = '\0';
 
   prefix_text2 = prefix_text;
-  elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, 1);
+  elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, NULL, 1);
   if (elt == NULL || elt == CMD_LIST_AMBIGUOUS)
     {
       msg = xstrprintf (_("could not find command prefix '%s'"), prefix_text);
diff --git a/gdb/guile/scm-param.c b/gdb/guile/scm-param.c
index 6d24c2c37b..adadb42e10 100644
--- a/gdb/guile/scm-param.c
+++ b/gdb/guile/scm-param.c
@@ -466,13 +466,13 @@ add_setshow_generic (enum var_types param_type, enum command_class cmd_class,
   /* Lookup created parameter, and register Scheme object against the
      parameter context.  Perform this task against both lists.  */
   tmp_name = cmd_name;
-  param = lookup_cmd (&tmp_name, *show_list, "", 0, 1);
+  param = lookup_cmd (&tmp_name, *show_list, "", NULL, 0, 1);
   gdb_assert (param != NULL);
   set_cmd_context (param, self);
   *set_cmd = param;
 
   tmp_name = cmd_name;
-  param = lookup_cmd (&tmp_name, *set_list, "", 0, 1);
+  param = lookup_cmd (&tmp_name, *set_list, "", NULL, 0, 1);
   gdb_assert (param != NULL);
   set_cmd_context (param, self);
   *show_cmd = param;
@@ -969,7 +969,7 @@ pascm_parameter_defined_p (const char *name, struct cmd_list_element *list)
 {
   struct cmd_list_element *c;
 
-  c = lookup_cmd_1 (&name, list, NULL, 1);
+  c = lookup_cmd_1 (&name, list, NULL, NULL, 1);
 
   /* If the name is ambiguous that's ok, it's a new parameter still.  */
   return c != NULL && c != CMD_LIST_AMBIGUOUS;
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 465d3a10e5..e63ae9b40a 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -3146,7 +3146,7 @@ is restored."),
 				     show_inferior_tty_command,
 				     &setlist, &showlist);
   cmd_name = "inferior-tty";
-  c = lookup_cmd (&cmd_name, setlist, "", -1, 1);
+  c = lookup_cmd (&cmd_name, setlist, "", NULL, -1, 1);
   gdb_assert (c != NULL);
   add_alias_cmd ("tty", c, class_alias, 0, &cmdlist);
 
@@ -3159,7 +3159,7 @@ Follow this command with any number of args, to be passed to the program."),
 				   set_args_command,
 				   show_args_command,
 				   &setlist, &showlist);
-  c = lookup_cmd (&cmd_name, setlist, "", -1, 1);
+  c = lookup_cmd (&cmd_name, setlist, "", NULL, -1, 1);
   gdb_assert (c != NULL);
   set_cmd_completer (c, filename_completer);
 
@@ -3178,7 +3178,7 @@ working directory."),
 				   set_cwd_command,
 				   show_cwd_command,
 				   &setlist, &showlist);
-  c = lookup_cmd (&cmd_name, setlist, "", -1, 1);
+  c = lookup_cmd (&cmd_name, setlist, "", NULL, -1, 1);
   gdb_assert (c != NULL);
   set_cmd_completer (c, filename_completer);
 
diff --git a/gdb/python/py-auto-load.c b/gdb/python/py-auto-load.c
index ade2aa1b37..af41c7c459 100644
--- a/gdb/python/py-auto-load.c
+++ b/gdb/python/py-auto-load.c
@@ -84,12 +84,12 @@ Show the debugger's behaviour regarding auto-loaded Python scripts, "
 			   NULL, NULL, show_auto_load_python_scripts,
 			   &setlist, &showlist);
   cmd_name = "auto-load-scripts";
-  cmd = lookup_cmd (&cmd_name, setlist, "", -1, 1);
+  cmd = lookup_cmd (&cmd_name, setlist, "", NULL, -1, 1);
   deprecate_cmd (cmd, "set auto-load python-scripts");
 
   /* It is needed because lookup_cmd updates the CMD_NAME pointer.  */
   cmd_name = "auto-load-scripts";
-  cmd = lookup_cmd (&cmd_name, showlist, "", -1, 1);
+  cmd = lookup_cmd (&cmd_name, showlist, "", NULL, -1, 1);
   deprecate_cmd (cmd, "show auto-load python-scripts");
 
   add_cmd ("python-scripts", class_info, info_auto_load_python_scripts,
diff --git a/gdb/python/py-cmd.c b/gdb/python/py-cmd.c
index 87d1888c52..70e328080c 100644
--- a/gdb/python/py-cmd.c
+++ b/gdb/python/py-cmd.c
@@ -396,7 +396,7 @@ gdbpy_parse_command_name (const char *name,
   std::string prefix_text (name, i + 1);
 
   prefix_text2 = prefix_text.c_str ();
-  elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, 1);
+  elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, NULL, 1);
   if (elt == NULL || elt == CMD_LIST_AMBIGUOUS)
     {
       PyErr_Format (PyExc_RuntimeError, _("Could not find command prefix %s."),
diff --git a/gdb/python/py-param.c b/gdb/python/py-param.c
index 4794366583..6233f119ef 100644
--- a/gdb/python/py-param.c
+++ b/gdb/python/py-param.c
@@ -569,12 +569,12 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
   /* Lookup created parameter, and register Python object against the
      parameter context.  Perform this task against both lists.  */
   tmp_name = cmd_name;
-  param = lookup_cmd (&tmp_name, *show_list, "", 0, 1);
+  param = lookup_cmd (&tmp_name, *show_list, "", NULL, 0, 1);
   if (param)
     set_cmd_context (param, self);
 
   tmp_name = cmd_name;
-  param = lookup_cmd (&tmp_name, *set_list, "", 0, 1);
+  param = lookup_cmd (&tmp_name, *set_list, "", NULL, 0, 1);
   if (param)
     set_cmd_context (param, self);
 }
diff --git a/gdb/remote.c b/gdb/remote.c
index 5e1745db44..7a841f0500 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -14294,10 +14294,10 @@ If set, a break, instead of a cntrl-c, is sent to the remote target."),
 			   set_remotebreak, show_remotebreak,
 			   &setlist, &showlist);
   cmd_name = "remotebreak";
-  cmd = lookup_cmd (&cmd_name, setlist, "", -1, 1);
+  cmd = lookup_cmd (&cmd_name, setlist, "", NULL, -1, 1);
   deprecate_cmd (cmd, "set remote interrupt-sequence");
   cmd_name = "remotebreak"; /* needed because lookup_cmd updates the pointer */
-  cmd = lookup_cmd (&cmd_name, showlist, "", -1, 1);
+  cmd = lookup_cmd (&cmd_name, showlist, "", NULL, -1, 1);
   deprecate_cmd (cmd, "show remote interrupt-sequence");
 
   add_setshow_enum_cmd ("interrupt-sequence", class_support,
diff --git a/gdb/top.c b/gdb/top.c
index 15d4fab8be..f546a3c667 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -533,6 +533,11 @@ set_repeat_arguments (const char *args)
   repeat_arguments = args;
 }
 
+/* Flag for whether we want to use the configured leading args.
+   Default is yes.  */
+
+static bool enable_leading_args_var = true;
+
 /* Execute the line P as a command, in the current user context.
    Pass FROM_TTY as second argument to the defining function.  */
 
@@ -561,6 +566,8 @@ execute_command (const char *p, int from_tty)
     {
       const char *cmd = p;
       const char *arg;
+      const char *leading_args;
+      std::string leading_args_and_arg;
       int was_sync = current_ui->prompt_state == PROMPT_BLOCKED;
 
       line = p;
@@ -568,15 +575,27 @@ execute_command (const char *p, int from_tty)
       /* If trace-commands is set then this will print this command.  */
       print_command_trace ("%s", p);
 
-      c = lookup_cmd (&cmd, cmdlist, "", 0, 1);
+      c = lookup_cmd (&cmd, cmdlist, "", &leading_args, 0, 1);
       p = cmd;
 
       scoped_restore save_repeat_args
 	= make_scoped_restore (&repeat_arguments, nullptr);
       const char *args_pointer = p;
 
-      /* Pass null arg rather than an empty one.  */
-      arg = *p ? p : 0;
+      if (leading_args != nullptr && enable_leading_args_var)
+	{
+	  if (*p)
+	    leading_args_and_arg = std::string (leading_args)
+	      + ' ' + std::string (p);
+	  else
+	    leading_args_and_arg = std::string (leading_args);
+	  arg = leading_args_and_arg.c_str ();
+	}
+      else
+	{
+	  /* Pass null arg rather than an empty one.  */
+	  arg = *p ? p : 0;
+	}
 
       /* FIXME: cagney/2002-02-02: The c->type test is pretty dodgy
          while the is_complete_command(cfunc) test is just plain
@@ -1883,7 +1902,7 @@ set_verbose (const char *args, int from_tty, struct cmd_list_element *c)
   const char *cmdname = "verbose";
   struct cmd_list_element *showcmd;
 
-  showcmd = lookup_cmd_1 (&cmdname, showlist, NULL, 1);
+  showcmd = lookup_cmd_1 (&cmdname, showlist, NULL, NULL, 1);
   gdb_assert (showcmd != NULL && showcmd != CMD_LIST_AMBIGUOUS);
 
   if (c->doc && c->doc_allocated)
@@ -2113,6 +2132,19 @@ EMACS-like or VI-like commands like control-P or ESC."),
 			   show_editing,
 			   &setlist, &showlist);
 
+  add_setshow_boolean_cmd ("enable-leading-args", class_support,
+			   &enable_leading_args_var, _("\
+Set whether GDB prepends leading args when running a command.\n\
+The leading args for a command are configured using\n\
+\"set leading-args COMMAND = LEADING-ARGS..."), _("\
+Show whether GDB prepends leading args when running a command."), _("\
+Use \"on\" to enable the usage of the configured leading args,\n\
+and \"off\" to disable it.\n\
+Without an argument, leading args usage is enabled."),
+			   NULL,
+			   NULL,
+			   &setlist, &showlist);
+
   add_setshow_boolean_cmd ("save", no_class, &write_history_p, _("\
 Set saving of the history record on exit."), _("\
 Show saving of the history record on exit."), _("\
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index 4db70607ef..40e6b03663 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -651,7 +651,7 @@ validate_actionline (const char *line, struct breakpoint *b)
   if (*p == '#')		/* comment line */
     return;
 
-  c = lookup_cmd (&p, cmdlist, "", -1, 1);
+  c = lookup_cmd (&p, cmdlist, "", NULL, -1, 1);
   if (c == 0)
     error (_("`%s' is not a tracepoint action, or is ambiguous."), p);
 
@@ -1309,7 +1309,7 @@ encode_actions_1 (struct command_line *action,
       action_exp = action->line;
       action_exp = skip_spaces (action_exp);
 
-      cmd = lookup_cmd (&action_exp, cmdlist, "", -1, 1);
+      cmd = lookup_cmd (&action_exp, cmdlist, "", NULL, -1, 1);
       if (cmd == 0)
 	error (_("Bad action list item: %s"), action_exp);
 
@@ -2679,7 +2679,7 @@ trace_dump_actions (struct command_line *action,
       if (*action_exp == '#')	/* comment line */
 	continue;
 
-      cmd = lookup_cmd (&action_exp, cmdlist, "", -1, 1);
+      cmd = lookup_cmd (&action_exp, cmdlist, "", NULL, -1, 1);
       if (cmd == 0)
 	error (_("Bad action list item: %s"), action_exp);
 
-- 
2.20.1


From 90dcc6725bfc1d4d3e285e902c2fb3863002c53a Mon Sep 17 00:00:00 2001
From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Sun, 23 Jun 2019 23:13:57 +0200
Subject: [PATCH 2/3] Add tests for new leading-args related commands and
 arguments.

Test the new leading-args behaviour and completion.
Note that gdb.base/leading-args.exp is somewhat copied from
with.exp (the test of the with command), while leading-exp.c
is a plain copy of with.c.

gdb/testsuite/ChangeLog
2019-09-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* gdb.base/leading-args.exp: New test.
	* gdb.base/leading.c: New file.
	* gdb.base/alias.exp: Update expected error msg for alias foo=bar.
---
 gdb/testsuite/gdb.base/alias.exp        |   2 +-
 gdb/testsuite/gdb.base/leading-args.c   |  41 +++++++
 gdb/testsuite/gdb.base/leading-args.exp | 151 ++++++++++++++++++++++++
 3 files changed, 193 insertions(+), 1 deletion(-)
 create mode 100644 gdb/testsuite/gdb.base/leading-args.c
 create mode 100644 gdb/testsuite/gdb.base/leading-args.exp

diff --git a/gdb/testsuite/gdb.base/alias.exp b/gdb/testsuite/gdb.base/alias.exp
index 20722e5dea..764d3ff8ff 100644
--- a/gdb/testsuite/gdb.base/alias.exp
+++ b/gdb/testsuite/gdb.base/alias.exp
@@ -56,7 +56,7 @@ test_abbrev_alias set6 "alias -a -- set6 = set" 46
 test_abbrev_alias -a "alias -a -- -a = set" 47
 
 gdb_test "alias set2=set" "already exists: set2"
-gdb_test "alias foo=bar" "Invalid command to alias to: bar"
+gdb_test "alias foo=bar" "Undefined command: \"bar\".  Try \"help\"."
 
 gdb_test_no_output "alias spe = set p elem"
 gdb_test_no_output "spe 50"
diff --git a/gdb/testsuite/gdb.base/leading-args.c b/gdb/testsuite/gdb.base/leading-args.c
new file mode 100644
index 0000000000..c6426625d4
--- /dev/null
+++ b/gdb/testsuite/gdb.base/leading-args.c
@@ -0,0 +1,41 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   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/>.  */
+
+int xxx1 = 123;
+
+struct S
+{
+  int a;
+  int b;
+  int c;
+};
+
+struct S g_s = {1, 2, 3};
+
+static void
+inc ()
+{
+  g_s.a++;;
+}
+
+int
+main ()
+{
+  inc ();
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/leading-args.exp b/gdb/testsuite/gdb.base/leading-args.exp
new file mode 100644
index 0000000000..ecc308fb51
--- /dev/null
+++ b/gdb/testsuite/gdb.base/leading-args.exp
@@ -0,0 +1,151 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# 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 "leading-args" related commands and arguments.
+
+load_lib completion-support.exp
+
+standard_testfile .c
+
+if {[build_executable "failed to prepare" $testfile $srcfile debug]} {
+    return -1
+}
+
+clean_restart $binfile
+
+# Basic/core tests using user-visible commands.
+with_test_prefix "basics" {
+    # Define an alias to pretty print something.
+    gdb_test "print g_s" " = {a = 1, b = 2, c = 3}" "simple print"
+    gdb_test_no_output "alias PP = print -pretty --" "alias PP"
+    gdb_test "show leading-args PP" "leading-args PP = -pretty --"
+    gdb_test "PP g_s" \
+	[multi_line  \
+	     " = {" \
+	     "  a = 1," \
+	     "  b = 2," \
+	     "  c = 3" \
+	     "}"]
+
+    # Define leading-args for "inspect", should not impact "print".
+    gdb_test_no_output "set leading-args inspect -pretty --" "inspect -pretty"
+    gdb_test "show leading-args inspect" "leading-args inspect = -pretty --"
+    gdb_test "print g_s" " = {a = 1, b = 2, c = 3}" "simple print not impacted"
+    gdb_test "inspect g_s" \
+	[multi_line  \
+	     " = {" \
+	     "  a = 1," \
+	     "  b = 2," \
+	     "  c = 3" \
+	     "}"]
+
+    # Set hex as default FMT for print.
+    gdb_test_no_output "set leading-args print -- /x" "print hex"
+    gdb_test "inspect g_s" \
+	[multi_line  \
+	     " = {" \
+	     "  a = 1," \
+	     "  b = 2," \
+	     "  c = 3" \
+	     "}"] "inspect g_s still pretty"
+    gdb_test "print g_s" " = {a = 0x1, b = 0x2, c = 0x3}" "simple print hex"
+
+    # Test disabling leading args.
+    gdb_test "show enable-leading-args" \
+	"Whether GDB prepends leading args when running a command is on\."
+    gdb_test_no_output "set enable-leading-args off"
+    gdb_test "print g_s" " = {a = 1, b = 2, c = 3}" \
+	"simple print with enable-leading-args off"
+    gdb_test_no_output "set enable-leading-args on"
+    
+
+    # Define leading-args for an alias of frame apply all
+    gdb_test_no_output "alias frame apply tout = frame apply all -past-entry -past-main" \
+	"alias frame apply tout"
+    gdb_test "show leading-args frame apply tout" \
+	"leading-args frame apply tout = -past-entry -past-main"
+
+    # Show all leading args.
+    gdb_test "show leading-args" \
+	[multi_line  \
+	     "leading-args PP = -pretty --" \
+	     "leading-args frame apply tout = -past-entry -past-main" \
+	     "leading-args inspect = -pretty --" \
+	     "leading-args print = -- /x"] "show leading-args"
+
+    # Clear the leading-args of "inspect".
+    gdb_test_no_output "set leading-args inspect" "clear inspect leading-args"
+    gdb_test "show leading-args inspect" "leading-args inspect = <no leading args>"
+    gdb_test "inspect g_s" " = {a = 1, b = 2, c = 3}" "simple inspect"
+
+}
+
+# Check errors.
+with_test_prefix "errors" {
+    # Try an unknown root setting.
+    gdb_test "set leading-args xxxx yyyy -someoption" \
+	"Undefined command: \"xxxx\".  Try \"help\"\\."
+
+    # Try ambiguous command.
+    gdb_test "set leading-args a" \
+	"Ambiguous command \"a\":.*" "ambiguous a"
+    gdb_test "set leading-args frame a" \
+	"Ambiguous frame command \"a\":.*" "ambiguous frame a"
+}
+
+
+# Check completion.
+with_test_prefix "completion" {
+    test_gdb_complete_unique \
+	"alias set pri" \
+	"alias set print"
+
+    test_gdb_complete_unique \
+	"alias set print items = set pri" \
+	"alias set print items = set print"
+
+    test_gdb_complete_unique \
+	"alias set print items = set print ele" \
+	"alias set print items = set print elements"
+
+   test_gdb_complete_unique \
+	"alias btfu = backt" \
+	"alias btfu = backtrace"
+
+   test_gdb_complete_unique \
+	"alias btfu = backtrace -fu" \
+	"alias btfu = backtrace -full"
+
+   test_gdb_complete_unique \
+	"alias btfu = backtrace -full -past-e" \
+	"alias btfu = backtrace -full -past-entry"
+
+    gdb_test_no_output "alias btfu = backtrace -full -past-entry" \
+	"alias btfu"
+
+    # Test completion of 'set leading-args' (sharing most
+    # of the code that alias command uses to complete after
+    # the first =.
+    test_gdb_complete_unique \
+	"set leading-args btf" \
+	"set leading-args btfu"
+
+    test_gdb_complete_unique \
+	"set leading-args btfu -frame-a" \
+	"set leading-args btfu -frame-arguments"
+
+}
-- 
2.20.1


From 65bd84e184d6d8f82cf6f12312db3718b2cb08ee Mon Sep 17 00:00:00 2001
From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Tue, 25 Jun 2019 00:50:29 +0200
Subject: [PATCH 3/3] NEWS and documentation for leading-args related concept
 and commands.

gdb/ChangeLog
2019-09-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* NEWS: Mention new leading-args commands.  Mention change
	to the alias command.

gdb/doc/ChangeLog
2019-09-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* gdb.texinfo (Command leading args): New node documenting
	'set|show leading-args' and 'set|show enable-leading-args'.
	(Aliases): Document the new 'LEADING-ARGS...' option.
---
 gdb/NEWS            |  18 +++++++
 gdb/doc/gdb.texinfo | 126 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 143 insertions(+), 1 deletion(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 25e67e43c8..47a755ca8c 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -96,6 +96,18 @@ w SETTING [VALUE] [-- COMMAND]
 maint with SETTING [VALUE] [-- COMMAND]
   Like "with", but works with "maintenance set" settings.
 
+set leading-args COMMAND [LEADING-ARGS...]
+show leading-args [COMMAND]
+set enable-leading-args [on|off]
+show enable-leading-args
+  GDB can now automatically prepend leading args to a command or alias.
+  This allows to set default arguments or options for the GDB commands
+  or define easier to use aliases.
+  For example, 'set leading-args backtrace -full -frame-arguments all'
+  ensures that backtrace will automatically use the options -full
+  -frame-arguments all, without having to retype them for each backtrace
+  command.
+
 set may-call-functions [on|off]
 show may-call-functions
   This controls whether GDB will attempt to call functions in
@@ -174,6 +186,12 @@ info sources [-dirname | -basename] [--] [REGEXP]
   allow to restrict matching respectively to the dirname and basename
   parts of the files.
 
+alias [-a] [--] ALIAS = COMMAND [LEADING-ARGS...]
+  The alias command can now directly define leading-args
+  to prepend to arguments provided by the user on the command line.
+  See 'set leading-args COMMAND [LEADING-ARGS...]' for more
+  information about leading args concept.
+
 show style
   The "show style" and its subcommands are now styling
   a style name in their output using its own style, to help
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1208e4f615..30732886db 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -1564,6 +1564,7 @@ show you the alternatives available, if there is more than one possibility).
 * Command Settings::            How to change default behavior of commands
 * Completion::                  Command completion
 * Command Options::             Command options
+* Command leading args::        Automatically prepend arguments to commands and aliases
 * Help::                        How to ask @value{GDBN} for help
 @end menu
 
@@ -1984,6 +1985,116 @@ uppercase.
 (For more on using the @code{print} command, see @ref{Data, ,Examining
 Data}.)
 
+@node Command leading args
+@section Automatically prepend arguments to commands and aliases
+
+You can tell @value{GDBN} to always add some default options or
+arguments to a command.
+
+@cindex command options, automatically prepend
+@cindex command, default arguments
+
+@table @code
+@kindex set leading-args
+@item set leading-args @var{command} [@var{leading-args@dots{}}]
+
+If you repetitively use the same arguments or options for a command,
+you can tell @value{GDBN} to automatically prepend these arguments
+or options to the arguments you type explicitely.
+
+For example, if you always want to have the command @code{thread apply all}
+working on the threads in ascending order and to continue in case it
+encounters an error, you can tell @value{GDBN} to automatically preprend
+the @code{-ascending} and @code{-c} options by using:
+
+@smallexample
+(@value{GDBP}) set leading-args thread apply all -ascending -c
+@end smallexample
+
+Once you have set these leading args, any time you type
+the @code{thread apply all} followed by @code{some arguments},
+@value{GDBN} will execute  @code{thread apply all -ascending -c some arguments}.
+
+As usual, unambiguous abbreviations can be used for @var{command}
+and @var{leading-args}.
+
+Commands and their aliases do not share their leading args.
+So, for example, you can configure the commands @code{bt}, @code{where},
+@code{backtrace} and @code{info stack} to output different levels
+of information and define a new alias @code{bt_ALL} showing all possible
+information using:
+@smallexample
+(@value{GDBP}) set leading-args bt -entry-values no -frame-arguments none
+(@value{GDBP}) set leading-args where -entry-values no -frame-argu scalars
+(@value{GDBP}) set leading-args backtrace -entry-values no -frame-argu all
+(@value{GDBP}) set leading-args info stack -entry-val both -fr all
+(@value{GDBP}) alias bt_ALL = backtrace
+(@value{GDBP}) set leading-args bt_ALL -entry-values both -frame-arg all \
+-past-main -past-entry -full
+@end smallexample
+
+You can define an alias and specify its leading args in one command using the shorter to type:
+@smallexample
+(@value{GDBP}) alias bt_ALL = backtrace -entry-values both -frame-arg all \
+-past-main -past-entry -full
+@end smallexample
+(For more on using the @code{alias} command, see @ref{Aliases}.)
+
+Leading args are not limited to the arguments and options of @var{command},
+but can specify nested commands if @var{command} accepts such a nested command
+as argument.
+For example, the below defines @code{faalocalsoftype} that can be used to list
+the frames having locals of a certain type, together with the matching local
+vars:
+@smallexample
+(@value{GDBP}) alias faalocalsoftype = frame apply all info locals -q -t
+(@value{GDBP}) faalocalsoftype int
+#1  0x55554f5e in sleeper_or_burner (v=0xdf50) at sleepers.c:86
+i = 0
+ret = 21845
+@end smallexample
+
+This is also very useful to define an alias for a set of nested @code{with}
+commands to have a particular combination of temporary settings.  For example,
+the below defines the alias @code{pp10} that pretty prints an expression
+argument, with a maximum of 10 elements if the expression is a string or
+an array:
+@smallexample
+(@value{GDBP}) alias pp10 = with print pretty -- with print elem 10 -- print
+@end smallexample
+
+
+Use @code{set leading-args @var{command}} (without giving @var{LEADING-ARGS})
+to clear the leading args of @var{command}.
+
+@item show leading-args [@var{command}]
+
+Use @code{show leading-args @var{command}} to show the current values of
+the leading args for @var{command}.  For example:
+@smallexample
+(@value{GDBP}) show leading-args backtrace
+leading-args backtrace = -entry-values no -frame-arguments all
+(@value{GDBP}) show leading-args break
+leading-args break = <no leading args>
+@end smallexample
+
+To show all the commands and aliases that have some leading args configured,
+use the command
+@code{show leading-args} without giving a @var{command} argument. 
+
+@item set enable-leading-args @r{[}on|off@r{]}
+@itemx show enable-leading-args
+By default, @value{GDBN} will use the configured leading args.
+This can be disabled using @code{set enable-leading-args off}.
+The leading args of all commands are not cleared, but
+will not be used till you do @code{set enable-leading-args on}.
+This can be useful in user defined commands to ensure only the specified
+set of options are used by a command launched by the user-defined command.
+You can also use this setting in the @code{with} command, to temporarily
+run a command without its possibly configured leading args.
+
+@end table
+
 @node Help
 @section Getting Help
 @cindex online documentation
@@ -27150,7 +27261,7 @@ You can define a new alias with the @samp{alias} command.
 @table @code
 
 @kindex alias
-@item alias [-a] [--] @var{ALIAS} = @var{COMMAND}
+@item alias [-a] [--] @var{ALIAS} = @var{COMMAND} [LEADING-ARGS...]
 
 @end table
 
@@ -27168,6 +27279,19 @@ lists displayed by the @samp{help} command.
 The @samp{--} option specifies the end of options,
 and is useful when @var{ALIAS} begins with a dash.
 
+You can specify @var{leading-args} for your alias.
+These @var{leading-args} will be automatically added before the alias
+arguments typed explicitely on the command line.
+
+For example, the below defines an alias @code{btfullall} that shows all local
+variables and all frame arguments:
+@smallexample
+(@value{GDBP}) alias btfullall = backtrace -full -frame-arguments all
+@end smallexample
+
+For more information about @var{leading-args}, see @ref{Command leading args,
+,Automatically prepend arguments to commands and aliases}
+
 Here is a simple example showing how to make an abbreviation
 of a command so that there is less to type.
 Suppose you were tired of typing @samp{disas}, the current
