[PATCH v6 6/8] GDB: Allow arbitrary keywords in integer set commands

["Maciej W. Rozycki" <macro@embecosm.com>]

Rather than just `unlimited' allow the integer set commands (or command 
options) to define arbitrary keywords for the user to use, removing 
hardcoded arrangements for the `unlimited' keyword.

Remove the confusingly named `var_zinteger', `var_zuinteger' and 
`var_zuinteger_unlimited' `set'/`show' command variable types redefining 
them in terms of `var_uinteger', `var_integer' and `var_pinteger', which 
have the range of [0;UINT_MAX], [INT_MIN;INT_MAX], and [0;INT_MAX] each.

Following existing practice `var_pinteger' allows extra negative values 
to be used, however unlike `var_zuinteger_unlimited' any number of such 
values can be defined rather than just `-1'.

The "p" in `var_pinteger' stands for "positive", for the lack of a more 
appropriate unambiguous letter, even though 0 obviously is not positive; 
"n" would be confusing as to whether it stands for "non-negative" or 
"negative".

Add a new structure, `literal_def', the entries of which define extra 
keywords allowed for a command and numerical values they correspond to.  
Those values are not verified against the basic range supported by the 
underlying variable type, allowing extra values to be allowed outside 
that range, which may or may not be individually made visible to the 
user.  An optional value translation is possible with the structure to 
follow the existing practice for some commands where user-entered 0 is 
internally translated to UINT_MAX or INT_MAX.  Such translation can now 
be arbitrary.  Literals defined by this structure are automatically used 
for completion as necessary.

So for example:

const literal_def integer_unlimited_literals[] =
  {
    { "unlimited", INT_MAX, 0 },
    { nullptr }
  };

defines an extra `unlimited' keyword and a user-visible 0 value, both of 
which get translated to INT_MAX for the setting to be used with.

Similarly:

const literal_def zuinteger_unlimited_literals[] =
  {
    { "unlimited", -1, -1 },
    { nullptr }
  };

defines the same keyword and a corresponding user-visible -1 value that 
is used for the requested setting.  If the last member were omitted (or 
set to `{}') here, then only the keyword would be allowed for the user 
to enter and while -1 would still be used internally trying to enter it 
as a part of a command would result in an "integer -1 out of range" 
error.

Use said error message in all cases (citing the invalid value requested) 
replacing "only -1 is allowed to set as unlimited" previously used for 
`var_zuinteger_unlimited' settings only rather than propagating it to 
`var_pinteger' type.  It could only be used for the specific case where 
a single extra `unlimited' keyword was defined standing for -1 and the 
use of numeric equivalents is discouraged anyway as it is for historical 
reasons only that they expose GDB internals, confusingly different 
across variable types.  Similarly update the "must be >= -1" Guile error 
message.

Redefine Guile and Python parameter types in terms of the new variable 
types and interpret extra keywords as Scheme keywords and Python strings 
used to communicate corresponding parameter values.  Do not add a new
PARAM_INTEGER Guile parameter type, however do handle the `var_integer' 
variable type now, permitting existing parameters defined by GDB proper, 
such as `listsize', to be accessed from Scheme code.

With these changes in place it should be trivial for a Scheme or Python 
programmer to expand the syntax of the `make-parameter' command and the 
`gdb.Parameter' class initializer to have arbitrary extra literals along 
with their internal representation supplied.

Update the testsuite accordingly.
---
Changes from v5:

- Add a translation layer from Guile and Python parameter types to new
  GDB variable types and remove `var_zuinteger', `var_uinteger', and 
  `var_zuinteger_unlimited' variable types altogether now.

- Add an optional `extra_literals' initialiser to the `setting' class
  constructor.

- Remove the "only -1 is allowed to set as unlimited" error message
  altogether now rather than propagating it to `var_pinteger' type.

- Make the `val' member of `struct literal_def' optional and remove the
  `allow' member; simplify processing accordingly.

- Rename `zuinteger_unlimited_literals' to `pinteger_unlimited_literals',
  making the names of all `*_unlimited_literals' arrays consistent with 
  the corresponding `var_*' variable types.

- Rename `struct integer_option_def' to `struct pinteger_option_def',
  observing it's come from `struct zuinteger_unlimited_option_def' and 
  what used to be the `var_zuinteger_unlimited' now has `var_pinteger' 
  semantics.

- Update the names of test flags used by `maint test-options' accordingly.

- Add constructor variants to `struct uinteger_option_def' and `struct
  pinteger_option_def' that allow one to skip the `extra_literals' 
  initialiser altogether rather than having to pass in `nullptr'.

- Update Python documentation mentioning the use of literal `unlimited'
  with the respective parameter types.

No change from v4.

New change in v4.
---
 gdb/cli/cli-cmds.c       |   56 ++++----
 gdb/cli/cli-decode.c     |  302 ++++++++++++++++++++++++++++++++++++++---------
 gdb/cli/cli-option.c     |  116 +++++++++++-------
 gdb/cli/cli-option.h     |   34 +++--
 gdb/cli/cli-setshow.c    |  249 ++++++++++++++++++--------------------
 gdb/cli/cli-setshow.h    |   20 +--
 gdb/command.h            |  108 ++++++++++++++--
 gdb/guile/scm-param.c    |  102 +++++++++------
 gdb/maint-test-options.c |    4 
 gdb/python/py-param.c    |   39 ++++--
 gdb/python/python.c      |   49 +++----
 gdb/valprint.c           |    9 -
 12 files changed, 716 insertions(+), 372 deletions(-)

gdb-setshow-cmd-extra-literals.diff
Index: src/gdb/cli/cli-cmds.c
===================================================================
--- src.orig/gdb/cli/cli-cmds.c
+++ src/gdb/cli/cli-cmds.c
@@ -2200,22 +2200,37 @@ value_from_setting (const setting &var,
 {
   switch (var.type ())
     {
+    case var_uinteger:
     case var_integer:
-      if (var.get<int> () == INT_MAX)
-	return value_from_longest (builtin_type (gdbarch)->builtin_int,
-				   0);
-      else
-	return value_from_longest (builtin_type (gdbarch)->builtin_int,
-				   var.get<int> ());
-    case var_zinteger:
-      return value_from_longest (builtin_type (gdbarch)->builtin_int,
-				 var.get<int> ());
+    case var_pinteger:
+      {
+	LONGEST value
+	  = (var.type () == var_uinteger
+	     ? static_cast<LONGEST> (var.get<unsigned int> ())
+	     : static_cast<LONGEST> (var.get<int> ()));
+
+	if (var.extra_literals () != nullptr)
+	  for (const literal_def *l = var.extra_literals ();
+	       l->literal != nullptr;
+	       l++)
+	    if (value == l->use)
+	      {
+		value = l->val;
+		break;
+	      }
+
+	if (var.type () == var_uinteger)
+	  return
+	    value_from_ulongest (builtin_type (gdbarch)->builtin_unsigned_int,
+				 static_cast<const unsigned int> (value));
+	else
+	  return
+	    value_from_longest (builtin_type (gdbarch)->builtin_int,
+				static_cast<const int> (value));
+      }
     case var_boolean:
       return value_from_longest (builtin_type (gdbarch)->builtin_int,
 				 var.get<bool> () ? 1 : 0);
-    case var_zuinteger_unlimited:
-      return value_from_longest (builtin_type (gdbarch)->builtin_int,
-				 var.get<int> ());
     case var_auto_boolean:
       {
 	int val;
@@ -2237,17 +2252,6 @@ value_from_setting (const setting &var,
 	return value_from_longest (builtin_type (gdbarch)->builtin_int,
 				   val);
       }
-    case var_uinteger:
-      if (var.get<unsigned int> () == UINT_MAX)
-	return value_from_ulongest
-	  (builtin_type (gdbarch)->builtin_unsigned_int, 0);
-      else
-	return value_from_ulongest
-	  (builtin_type (gdbarch)->builtin_unsigned_int,
-	   var.get<unsigned int> ());
-    case var_zuinteger:
-      return value_from_ulongest (builtin_type (gdbarch)->builtin_unsigned_int,
-				  var.get<unsigned int> ());
     case var_string:
     case var_string_noescape:
     case var_optional_filename:
@@ -2317,13 +2321,11 @@ str_value_from_setting (const setting &v
 {
   switch (var.type ())
     {
+    case var_uinteger:
     case var_integer:
-    case var_zinteger:
+    case var_pinteger:
     case var_boolean:
-    case var_zuinteger_unlimited:
     case var_auto_boolean:
-    case var_uinteger:
-    case var_zuinteger:
       {
 	std::string cmd_val = get_setshow_command_value_string (var);
 
Index: src/gdb/cli/cli-decode.c
===================================================================
--- src.orig/gdb/cli/cli-decode.c
+++ src/gdb/cli/cli-decode.c
@@ -580,11 +580,51 @@ add_setshow_cmd_full_erased (const char
   return {set, show};
 }
 
+/* Completes on integer commands that support extra literals.  */
+
+static void
+integer_literals_completer (struct cmd_list_element *c,
+			    completion_tracker &tracker,
+			    const char *text, const char *word)
+{
+  const literal_def *extra_literals = c->var->extra_literals ();
+
+  if (*text == '\0')
+    {
+      tracker.add_completion (make_unique_xstrdup ("NUMBER"));
+      for (const literal_def *l = extra_literals;
+	   l->literal != nullptr;
+	   l++)
+	tracker.add_completion (make_unique_xstrdup (l->literal));
+    }
+  else
+    for (const literal_def *l = extra_literals;
+	 l->literal != nullptr;
+	 l++)
+      if (startswith (l->literal, text))
+	tracker.add_completion (make_unique_xstrdup (l->literal));
+}
+
+/* Add element named NAME to both the command SET_LIST and SHOW_LIST.
+   THECLASS is as in add_cmd.  VAR_TYPE is the kind of thing we are
+   setting.  VAR is address of the variable being controlled by this
+   command.  EXTRA_LITERALS if non-NULL define extra literals to be
+   accepted in lieu of a number for integer variables.  If nullptr is
+   given as VAR, then both SET_SETTING_FUNC and GET_SETTING_FUNC must
+   be provided. SET_SETTING_FUNC and GET_SETTING_FUNC are callbacks
+   used to access and modify the underlying property, whatever its
+   storage is.  SET_FUNC and SHOW_FUNC are the callback functions
+   (if non-NULL).  SET_DOC, SHOW_DOC and HELP_DOC are the
+   documentation strings.
+
+   Return the newly created set and show commands.  */
+
 template<typename T>
 static set_show_commands
 add_setshow_cmd_full (const char *name,
 		      enum command_class theclass,
 		      var_types var_type, T *var,
+		      const literal_def *extra_literals,
 		      const char *set_doc, const char *show_doc,
 		      const char *help_doc,
 		      typename setting_func_types<T>::set set_setting_func,
@@ -595,18 +635,44 @@ add_setshow_cmd_full (const char *name,
 		      struct cmd_list_element **show_list)
 {
   auto erased_args
-    = setting::erase_args (var_type, var,
+    = setting::erase_args (var_type, var, extra_literals,
 			   set_setting_func, get_setting_func);
+  auto cmds = add_setshow_cmd_full_erased (name,
+					   theclass,
+					   var_type, erased_args,
+					   set_doc, show_doc,
+					   help_doc,
+					   set_func,
+					   show_func,
+					   set_list,
+					   show_list);
 
-  return add_setshow_cmd_full_erased (name,
-				      theclass,
-				      var_type, erased_args,
-				      set_doc, show_doc,
-				      help_doc,
-				      set_func,
-				      show_func,
-				      set_list,
-				      show_list);
+  if (extra_literals != nullptr)
+    set_cmd_completer (cmds.set, integer_literals_completer);
+
+  return cmds;
+}
+
+/* Same as above but omitting EXTRA_LITERALS.  */
+
+template<typename T>
+static set_show_commands
+add_setshow_cmd_full (const char *name,
+		      enum command_class theclass,
+		      var_types var_type, T *var,
+		      const char *set_doc, const char *show_doc,
+		      const char *help_doc,
+		      typename setting_func_types<T>::set set_setting_func,
+		      typename setting_func_types<T>::get get_setting_func,
+		      cmd_func_ftype *set_func,
+		      show_value_ftype *show_func,
+		      struct cmd_list_element **set_list,
+		      struct cmd_list_element **show_list)
+{
+  return add_setshow_cmd_full (name, theclass, var_type, var, nullptr,
+			       set_doc, show_doc, help_doc,
+			       set_setting_func, get_setting_func,
+			       set_func, show_func, set_list, show_list);
 }
 
 /* Add element named NAME to command list LIST (the list for set or
@@ -975,25 +1041,6 @@ add_setshow_optional_filename_cmd (const
   return cmds;
 }
 
-/* Completes on literal "unlimited".  Used by integer commands that
-   support a special "unlimited" value.  */
-
-static void
-integer_unlimited_completer (struct cmd_list_element *ignore,
-			     completion_tracker &tracker,
-			     const char *text, const char *word)
-{
-  static const char * const keywords[] =
-    {
-      "unlimited",
-      NULL,
-    };
-
-  if (*text == '\0')
-    tracker.add_completion (make_unique_xstrdup ("NUMBER"));
-  complete_on_enum (tracker, keywords, text, word);
-}
-
 /* Add element named NAME to both the set and show command LISTs (the
    list for set/show or some sublist thereof).  CLASS is as in
    add_cmd.  VAR is address of the variable which will contain the
@@ -1002,6 +1049,55 @@ integer_unlimited_completer (struct cmd_
 
 set_show_commands
 add_setshow_integer_cmd (const char *name, enum command_class theclass,
+			 int *var, const literal_def *extra_literals,
+			 const char *set_doc, const char *show_doc,
+			 const char *help_doc,
+			 cmd_func_ftype *set_func,
+			 show_value_ftype *show_func,
+			 struct cmd_list_element **set_list,
+			 struct cmd_list_element **show_list)
+{
+  set_show_commands commands
+    = add_setshow_cmd_full<int> (name, theclass, var_integer, var,
+				 extra_literals, set_doc, show_doc,
+				 help_doc, nullptr, nullptr, set_func,
+				 show_func, set_list, show_list);
+  return commands;
+}
+
+/* Same as above but using a getter and a setter function instead of a pointer
+   to a global storage buffer.  */
+
+set_show_commands
+add_setshow_integer_cmd (const char *name, command_class theclass,
+			 const literal_def *extra_literals,
+			 const char *set_doc, const char *show_doc,
+			 const char *help_doc,
+			 setting_func_types<int>::set set_func,
+			 setting_func_types<int>::get get_func,
+			 show_value_ftype *show_func,
+			 cmd_list_element **set_list,
+			 cmd_list_element **show_list)
+{
+  auto cmds = add_setshow_cmd_full<int> (name, theclass, var_integer, nullptr,
+					 extra_literals, set_doc, show_doc,
+					 help_doc, set_func, get_func, nullptr,
+					 show_func, set_list, show_list);
+  return cmds;
+}
+
+/* Accept `unlimited' or 0, translated internally to INT_MAX.  */
+const literal_def integer_unlimited_literals[] =
+  {
+    { "unlimited", 0, INT_MAX, true },
+    { nullptr }
+  };
+
+/* Same as above but using `integer_unlimited_literals', with a pointer
+   to a global storage buffer.  */
+
+set_show_commands
+add_setshow_integer_cmd (const char *name, enum command_class theclass,
 			 int *var,
 			 const char *set_doc, const char *show_doc,
 			 const char *help_doc,
@@ -1012,12 +1108,10 @@ add_setshow_integer_cmd (const char *nam
 {
   set_show_commands commands
     = add_setshow_cmd_full<int> (name, theclass, var_integer, var,
+				 integer_unlimited_literals,
 				 set_doc, show_doc, help_doc,
 				 nullptr, nullptr, set_func,
 				 show_func, set_list, show_list);
-
-  set_cmd_completer (commands.set, integer_unlimited_completer);
-
   return commands;
 }
 
@@ -1035,12 +1129,54 @@ add_setshow_integer_cmd (const char *nam
 			 cmd_list_element **show_list)
 {
   auto cmds = add_setshow_cmd_full<int> (name, theclass, var_integer, nullptr,
+					 integer_unlimited_literals,
 					 set_doc, show_doc, help_doc, set_func,
 					 get_func, nullptr, show_func, set_list,
 					 show_list);
+  return cmds;
+}
 
-  set_cmd_completer (cmds.set, integer_unlimited_completer);
+/* Add element named NAME to both the set and show command LISTs (the
+   list for set/show or some sublist thereof).  CLASS is as in
+   add_cmd.  VAR is address of the variable which will contain the
+   value.  SET_DOC and SHOW_DOC are the documentation strings.  */
+
+set_show_commands
+add_setshow_pinteger_cmd (const char *name, enum command_class theclass,
+			  int *var, const literal_def *extra_literals,
+			  const char *set_doc, const char *show_doc,
+			  const char *help_doc,
+			  cmd_func_ftype *set_func,
+			  show_value_ftype *show_func,
+			  struct cmd_list_element **set_list,
+			  struct cmd_list_element **show_list)
+{
+  set_show_commands commands
+    = add_setshow_cmd_full<int> (name, theclass, var_pinteger, var,
+				 extra_literals, set_doc, show_doc,
+				 help_doc, nullptr, nullptr, set_func,
+				 show_func, set_list, show_list);
+  return commands;
+}
 
+/* Same as above but using a getter and a setter function instead of a pointer
+   to a global storage buffer.  */
+
+set_show_commands
+add_setshow_pinteger_cmd (const char *name, command_class theclass,
+			  const literal_def *extra_literals,
+			  const char *set_doc, const char *show_doc,
+			  const char *help_doc,
+			  setting_func_types<int>::set set_func,
+			  setting_func_types<int>::get get_func,
+			  show_value_ftype *show_func,
+			  cmd_list_element **set_list,
+			  cmd_list_element **show_list)
+{
+  auto cmds = add_setshow_cmd_full<int> (name, theclass, var_pinteger, nullptr,
+					 extra_literals, set_doc, show_doc,
+					 help_doc, set_func, get_func, nullptr,
+					 show_func, set_list, show_list);
   return cmds;
 }
 
@@ -1051,7 +1187,7 @@ add_setshow_integer_cmd (const char *nam
 
 set_show_commands
 add_setshow_uinteger_cmd (const char *name, enum command_class theclass,
-			  unsigned int *var,
+			  unsigned int *var, const literal_def *extra_literals,
 			  const char *set_doc, const char *show_doc,
 			  const char *help_doc,
 			  cmd_func_ftype *set_func,
@@ -1061,12 +1197,9 @@ add_setshow_uinteger_cmd (const char *na
 {
   set_show_commands commands
     = add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger, var,
-					  set_doc, show_doc, help_doc,
-					  nullptr, nullptr, set_func,
+					  extra_literals, set_doc, show_doc,
+					  help_doc, nullptr, nullptr, set_func,
 					  show_func, set_list, show_list);
-
-  set_cmd_completer (commands.set, integer_unlimited_completer);
-
   return commands;
 }
 
@@ -1075,6 +1208,7 @@ add_setshow_uinteger_cmd (const char *na
 
 set_show_commands
 add_setshow_uinteger_cmd (const char *name, command_class theclass,
+			  const literal_def *extra_literals,
 			  const char *set_doc, const char *show_doc,
 			  const char *help_doc,
 			  setting_func_types<unsigned int>::set set_func,
@@ -1084,13 +1218,63 @@ add_setshow_uinteger_cmd (const char *na
 			  cmd_list_element **show_list)
 {
   auto cmds = add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger,
-						  nullptr, set_doc, show_doc,
-						  help_doc, set_func, get_func,
-						  nullptr, show_func, set_list,
+						  nullptr, extra_literals,
+						  set_doc, show_doc, help_doc,
+						  set_func, get_func, nullptr,
+						  show_func, set_list,
 						  show_list);
+  return cmds;
+}
 
-  set_cmd_completer (cmds.set, integer_unlimited_completer);
+/* Accept `unlimited' or 0, translated internally to UINT_MAX.  */
+const literal_def uinteger_unlimited_literals[] =
+  {
+    { "unlimited", 0, UINT_MAX, true },
+    { nullptr }
+  };
+
+/* Same as above but using `uinteger_unlimited_literals', with a pointer
+   to a global storage buffer.  */
+
+set_show_commands
+add_setshow_uinteger_cmd (const char *name, enum command_class theclass,
+			  unsigned int *var,
+			  const char *set_doc, const char *show_doc,
+			  const char *help_doc,
+			  cmd_func_ftype *set_func,
+			  show_value_ftype *show_func,
+			  struct cmd_list_element **set_list,
+			  struct cmd_list_element **show_list)
+{
+  set_show_commands commands
+    = add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger, var,
+					  uinteger_unlimited_literals,
+					  set_doc, show_doc, help_doc, nullptr,
+					  nullptr, set_func, show_func,
+					  set_list, show_list);
+  return commands;
+}
+
+/* Same as above but using a getter and a setter function instead of a pointer
+   to a global storage buffer.  */
 
+set_show_commands
+add_setshow_uinteger_cmd (const char *name, command_class theclass,
+			  const char *set_doc, const char *show_doc,
+			  const char *help_doc,
+			  setting_func_types<unsigned int>::set set_func,
+			  setting_func_types<unsigned int>::get get_func,
+			  show_value_ftype *show_func,
+			  cmd_list_element **set_list,
+			  cmd_list_element **show_list)
+{
+  auto cmds = add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger,
+						  nullptr,
+						  uinteger_unlimited_literals,
+						  set_doc, show_doc, help_doc,
+						  set_func, get_func, nullptr,
+						  show_func, set_list,
+						  show_list);
   return cmds;
 }
 
@@ -1109,7 +1293,7 @@ add_setshow_zinteger_cmd (const char *na
 			  struct cmd_list_element **set_list,
 			  struct cmd_list_element **show_list)
 {
-  return add_setshow_cmd_full<int> (name, theclass, var_zinteger, var,
+  return add_setshow_cmd_full<int> (name, theclass, var_integer, var,
 				    set_doc, show_doc, help_doc,
 				    nullptr, nullptr, set_func,
 				    show_func, set_list, show_list);
@@ -1128,12 +1312,22 @@ add_setshow_zinteger_cmd (const char *na
 			  cmd_list_element **set_list,
 			  cmd_list_element **show_list)
 {
-  return add_setshow_cmd_full<int> (name, theclass, var_zinteger, nullptr,
+  return add_setshow_cmd_full<int> (name, theclass, var_integer, nullptr,
 				    set_doc, show_doc, help_doc, set_func,
 				    get_func, nullptr, show_func, set_list,
 				    show_list);
 }
 
+/* Accept `unlimited' or -1, using -1 internally.  */
+const literal_def zuinteger_unlimited_literals[] =
+  {
+    { "unlimited", -1, -1, true },
+    { nullptr }
+  };
+
+/* Same as above but using `zuinteger_unlimited_literals', with a pointer
+   to a global storage buffer.  */
+
 set_show_commands
 add_setshow_zuinteger_unlimited_cmd (const char *name,
 				     enum command_class theclass,
@@ -1147,13 +1341,11 @@ add_setshow_zuinteger_unlimited_cmd (con
 				     struct cmd_list_element **show_list)
 {
   set_show_commands commands
-    = add_setshow_cmd_full<int> (name, theclass, var_zuinteger_unlimited, var,
+    = add_setshow_cmd_full<int> (name, theclass, var_pinteger, var,
+				 zuinteger_unlimited_literals,
 				 set_doc, show_doc, help_doc, nullptr,
 				 nullptr, set_func, show_func, set_list,
 				 show_list);
-
-  set_cmd_completer (commands.set, integer_unlimited_completer);
-
   return commands;
 }
 
@@ -1171,13 +1363,11 @@ add_setshow_zuinteger_unlimited_cmd (con
 				     cmd_list_element **show_list)
 {
   auto cmds
-    = add_setshow_cmd_full<int> (name, theclass, var_zuinteger_unlimited,
-				 nullptr, set_doc, show_doc, help_doc, set_func,
+    = add_setshow_cmd_full<int> (name, theclass, var_pinteger, nullptr,
+				 zuinteger_unlimited_literals,
+				 set_doc, show_doc, help_doc, set_func,
 				 get_func, nullptr, show_func, set_list,
 				 show_list);
-
-  set_cmd_completer (cmds.set, integer_unlimited_completer);
-
   return cmds;
 }
 
@@ -1196,7 +1386,7 @@ add_setshow_zuinteger_cmd (const char *n
 			   struct cmd_list_element **set_list,
 			   struct cmd_list_element **show_list)
 {
-  return add_setshow_cmd_full<unsigned int> (name, theclass, var_zuinteger,
+  return add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger,
 					     var, set_doc, show_doc, help_doc,
 					     nullptr, nullptr, set_func,
 					     show_func, set_list, show_list);
@@ -1215,7 +1405,7 @@ add_setshow_zuinteger_cmd (const char *n
 			   cmd_list_element **set_list,
 			   cmd_list_element **show_list)
 {
-  return add_setshow_cmd_full<unsigned int> (name, theclass, var_zuinteger,
+  return add_setshow_cmd_full<unsigned int> (name, theclass, var_uinteger,
 					     nullptr, set_doc, show_doc,
 					     help_doc, set_func, get_func,
 					     nullptr, show_func, set_list,
Index: src/gdb/cli/cli-option.c
===================================================================
--- src.orig/gdb/cli/cli-option.c
+++ src/gdb/cli/cli-option.c
@@ -38,7 +38,7 @@ union option_value
   /* For var_uinteger options.  */
   unsigned int uinteger;
 
-  /* For var_zuinteger_unlimited options.  */
+  /* For var_integer and var_pinteger options.  */
   int integer;
 
   /* For var_enum options.  */
@@ -356,42 +356,55 @@ parse_option (gdb::array_view<const opti
 	return option_def_and_value {*match, match_ctx, val};
       }
     case var_uinteger:
-    case var_zuinteger_unlimited:
+    case var_integer:
+    case var_pinteger:
       {
 	if (completion != nullptr)
 	  {
-	    if (**args == '\0')
-	      {
-		/* Convenience to let the user know what the option
-		   can accept.  Note there's no common prefix between
-		   the strings on purpose, so that readline doesn't do
-		   a partial match.  */
-		completion->tracker.add_completion
-		  (make_unique_xstrdup ("NUMBER"));
-		completion->tracker.add_completion
-		  (make_unique_xstrdup ("unlimited"));
-		return {};
-	      }
-	    else if (startswith ("unlimited", *args))
+	    if (match->extra_literals != nullptr)
 	      {
-		completion->tracker.add_completion
-		  (make_unique_xstrdup ("unlimited"));
-		return {};
+		/* Convenience to let the user know what the option can
+		   accept.  Make sure there's no common prefix between
+		   "NUMBER" and all the strings when adding new ones,
+		   so that readline doesn't do a partial match.  */
+		if (**args == '\0')
+		  {
+		    completion->tracker.add_completion
+		      (make_unique_xstrdup ("NUMBER"));
+		    for (const literal_def *l = match->extra_literals;
+			 l->literal != nullptr;
+			 l++)
+		      completion->tracker.add_completion
+			(make_unique_xstrdup (l->literal));
+		    return {};
+		  }
+		else
+		  {
+		    bool completions = false;
+		    for (const literal_def *l = match->extra_literals;
+			 l->literal != nullptr;
+			 l++)
+		      if (startswith (l->literal, *args))
+			{
+			  completion->tracker.add_completion
+			    (make_unique_xstrdup (l->literal));
+			  completions = true;
+			}
+		    if (completions)
+		      return {};
+		  }
 	      }
 	  }
 
-	if (match->type == var_zuinteger_unlimited)
-	  {
-	    option_value val;
-	    val.integer = parse_cli_var_zuinteger_unlimited (args, false);
-	    return option_def_and_value {*match, match_ctx, val};
-	  }
+	LONGEST v = parse_cli_var_integer (match->type,
+					   match->extra_literals,
+					   args, false);
+	option_value val;
+	if (match->type == var_uinteger)
+	  val.uinteger = v;
 	else
-	  {
-	    option_value val;
-	    val.uinteger = parse_cli_var_uinteger (match->type, args, false);
-	    return option_def_and_value {*match, match_ctx, val};
-	  }
+	  val.integer = v;
+	return option_def_and_value {*match, match_ctx, val};
       }
     case var_enum:
       {
@@ -593,7 +606,7 @@ save_option_value_in_ctx (gdb::optional<
       *ov->option.var_address.uinteger (ov->option, ov->ctx)
 	= ov->value->uinteger;
       break;
-    case var_zuinteger_unlimited:
+    case var_integer:
       *ov->option.var_address.integer (ov->option, ov->ctx)
 	= ov->value->integer;
       break;
@@ -664,8 +677,20 @@ get_val_type_str (const option_def &opt,
     case var_boolean:
       return "[on|off]";
     case var_uinteger:
-    case var_zuinteger_unlimited:
-      return "NUMBER|unlimited";
+    case var_integer:
+    case var_pinteger:
+      {
+	buffer = "NUMBER";
+	if (opt.extra_literals != nullptr)
+	  for (const literal_def *l = opt.extra_literals;
+	       l->literal != nullptr;
+	       l++)
+	    {
+	      buffer += '|';
+	      buffer += l->literal;
+	    }
+	return buffer.c_str ();
+      }
     case var_enum:
       {
 	buffer = "";
@@ -789,20 +814,31 @@ add_setshow_cmds_for_options (command_cl
 	{
 	  add_setshow_uinteger_cmd (option.name, cmd_class,
 				    option.var_address.uinteger (option, data),
+				    option.extra_literals,
 				    option.set_doc, option.show_doc,
 				    option.help_doc,
 				    nullptr, option.show_cmd_cb,
 				    set_list, show_list);
 	}
-      else if (option.type == var_zuinteger_unlimited)
+      else if (option.type == var_integer)
 	{
-	  add_setshow_zuinteger_unlimited_cmd
-	    (option.name, cmd_class,
-	     option.var_address.integer (option, data),
-	     option.set_doc, option.show_doc,
-	     option.help_doc,
-	     nullptr, option.show_cmd_cb,
-	     set_list, show_list);
+	  add_setshow_integer_cmd (option.name, cmd_class,
+				   option.var_address.integer (option, data),
+				   option.extra_literals,
+				   option.set_doc, option.show_doc,
+				   option.help_doc,
+				   nullptr, option.show_cmd_cb,
+				   set_list, show_list);
+	}
+      else if (option.type == var_pinteger)
+	{
+	  add_setshow_pinteger_cmd (option.name, cmd_class,
+				    option.var_address.integer (option, data),
+				    option.extra_literals,
+				    option.set_doc, option.show_doc,
+				    option.help_doc,
+				    nullptr, option.show_cmd_cb,
+				    set_list, show_list);
 	}
       else if (option.type == var_enum)
 	{
Index: src/gdb/cli/cli-option.h
===================================================================
--- src.orig/gdb/cli/cli-option.h
+++ src/gdb/cli/cli-option.h
@@ -49,12 +49,13 @@ struct option_def
      used to create the option's "set/show" commands.  */
   constexpr option_def (const char *name_,
 			var_types var_type_,
+			const literal_def *extra_literals_,
 			erased_get_var_address_ftype *erased_get_var_address_,
 			show_value_ftype *show_cmd_cb_,
 			const char *set_doc_,
 			const char *show_doc_,
 			const char *help_doc_)
-    : name (name_), type (var_type_),
+    : name (name_), type (var_type_), extra_literals (extra_literals_),
       erased_get_var_address (erased_get_var_address_),
       var_address {},
       show_cmd_cb (show_cmd_cb_),
@@ -68,6 +69,9 @@ struct option_def
   /* The option's type.  */
   var_types type;
 
+  /* Extra literals, such as `unlimited', accepted in lieu of a number.  */
+  const literal_def *extra_literals;
+
   /* A function that gets the controlling variable's address, type
      erased.  */
   erased_get_var_address_ftype *erased_get_var_address;
@@ -160,7 +164,7 @@ struct boolean_option_def : option_def
 		      const char *set_doc_,
 		      const char *show_doc_ = nullptr,
 		      const char *help_doc_ = nullptr)
-    : option_def (long_option_, var_boolean,
+    : option_def (long_option_, var_boolean, nullptr,
 		  (erased_get_var_address_ftype *) get_var_address_cb_,
 		  show_cmd_cb_,
 		  set_doc_, show_doc_, help_doc_)
@@ -207,11 +211,12 @@ struct uinteger_option_def : option_def
 {
   uinteger_option_def (const char *long_option_,
 		       unsigned int *(*get_var_address_cb_) (Context *),
+		       const literal_def *extra_literals_,
 		       show_value_ftype *show_cmd_cb_,
 		       const char *set_doc_,
 		       const char *show_doc_ = nullptr,
 		       const char *help_doc_ = nullptr)
-    : option_def (long_option_, var_uinteger,
+    : option_def (long_option_, var_uinteger, extra_literals_,
 		  (erased_get_var_address_ftype *) get_var_address_cb_,
 		  show_cmd_cb_,
 		  set_doc_, show_doc_, help_doc_)
@@ -220,18 +225,19 @@ struct uinteger_option_def : option_def
   }
 };
 
-/* A var_zuinteger_unlimited command line option.  */
+/* A var_integer command line option.  */
 
 template<typename Context>
-struct zuinteger_unlimited_option_def : option_def
+struct integer_option_def : option_def
 {
-  zuinteger_unlimited_option_def (const char *long_option_,
-				  int *(*get_var_address_cb_) (Context *),
-				  show_value_ftype *show_cmd_cb_,
-				  const char *set_doc_,
-				  const char *show_doc_ = nullptr,
-				  const char *help_doc_ = nullptr)
-    : option_def (long_option_, var_zuinteger_unlimited,
+  integer_option_def (const char *long_option_,
+		      int *(*get_var_address_cb_) (Context *),
+		      const literal_def *extra_literals_,
+		      show_value_ftype *show_cmd_cb_,
+		      const char *set_doc_,
+		      const char *show_doc_ = nullptr,
+		      const char *help_doc_ = nullptr)
+    : option_def (long_option_, var_integer, extra_literals_,
 		  (erased_get_var_address_ftype *) get_var_address_cb_,
 		  show_cmd_cb_,
 		  set_doc_, show_doc_, help_doc_)
@@ -252,7 +258,7 @@ struct enum_option_def : option_def
 		   const char *set_doc_,
 		   const char *show_doc_ = nullptr,
 		   const char *help_doc_ = nullptr)
-    : option_def (long_option_, var_enum,
+    : option_def (long_option_, var_enum, nullptr,
 		  (erased_get_var_address_ftype *) get_var_address_cb_,
 		  show_cmd_cb_,
 		  set_doc_, show_doc_, help_doc_)
@@ -273,7 +279,7 @@ struct string_option_def : option_def
 		     const char *set_doc_,
 		     const char *show_doc_ = nullptr,
 		     const char *help_doc_ = nullptr)
-    : option_def (long_option_, var_string,
+    : option_def (long_option_, var_string, nullptr,
 		  (erased_get_var_address_ftype *) get_var_address_cb_,
 		  show_cmd_cb_,
 		  set_doc_, show_doc_, help_doc_)
Index: src/gdb/cli/cli-setshow.c
===================================================================
--- src.orig/gdb/cli/cli-setshow.c
+++ src/gdb/cli/cli-setshow.c
@@ -149,10 +149,11 @@ deprecated_show_value_hack (struct ui_fi
     }
 }
 
-/* Returns true if ARG is "unlimited".  */
+/* Returns true and the value in VAL if ARG is an accepted literal.  */
 
 static bool
-is_unlimited_literal (const char **arg, bool expression)
+get_literal_val (LONGEST &val, const literal_def *extra_literals,
+		 const char **arg, bool expression)
 {
   *arg = skip_spaces (*arg);
 
@@ -162,85 +163,108 @@ is_unlimited_literal (const char **arg,
 
   size_t len = p - *arg;
 
-  if (len > 0 && strncmp ("unlimited", *arg, len) == 0)
-    {
-      *arg += len;
-
-      /* If parsing an expression (i.e., parsing for a "set" command),
-	 anything after "unlimited" is junk.  For options, anything
-	 after "unlimited" might be a command argument or another
-	 option.  */
-      if (expression)
+  if (len > 0 && extra_literals != nullptr)
+    for (const literal_def *l = extra_literals;
+	 l->literal != nullptr;
+	 l++)
+      if (strncmp (l->literal, *arg, len) == 0)
 	{
-	  const char *after = skip_spaces (*arg);
-	  if (*after != '\0')
-	    error (_("Junk after \"%.*s\": %s"),
-		   (int) len, unl_start, after);
-	}
+	  *arg += len;
 
-      return true;
-    }
+	  /* If parsing an expression (i.e., parsing for a "set" command),
+	     anything after the literal is junk.  For options, anything
+	     after the literal might be a command argument or another
+	     option.  */
+	  if (expression)
+	    {
+	      const char *after = skip_spaces (*arg);
+	      if (*after != '\0')
+		error (_("Junk after \"%.*s\": %s"),
+		       (int) len, unl_start, after);
+	    }
+
+	  val = l->use;
+	  return true;
+	}
 
   return false;
 }
 
 /* See cli-setshow.h.  */
 
-unsigned int
-parse_cli_var_uinteger (var_types var_type, const char **arg,
-			bool expression)
+LONGEST
+parse_cli_var_integer (var_types var_type, const literal_def *extra_literals,
+		       const char **arg, bool expression)
 {
   LONGEST val;
 
   if (*arg == nullptr || **arg == '\0')
     {
-      if (var_type == var_uinteger)
-	error_no_arg (_("integer to set it to, or \"unlimited\""));
-      else
+      if (extra_literals == nullptr)
 	error_no_arg (_("integer to set it to"));
-    }
-
-  if (var_type == var_uinteger && is_unlimited_literal (arg, expression))
-    val = 0;
-  else if (expression)
-    val = parse_and_eval_long (*arg);
-  else
-    val = get_ulongest (arg);
-
-  if (var_type == var_uinteger && val == 0)
-    val = UINT_MAX;
-  else if (val < 0
-	   /* For var_uinteger, don't let the user set the value
-	      to UINT_MAX directly, as that exposes an
-	      implementation detail to the user interface.  */
-	   || (var_type == var_uinteger && val >= UINT_MAX)
-	   || (var_type == var_zuinteger && val > UINT_MAX))
-    error (_("integer %s out of range"), plongest (val));
-
-  return val;
-}
-
-/* See cli-setshow.h.  */
+      else
+	{
+	  std::string buffer = "";
+	  size_t count = 0;
 
-int
-parse_cli_var_zuinteger_unlimited (const char **arg, bool expression)
-{
-  LONGEST val;
+	  for (const literal_def *l = extra_literals;
+	       l->literal != nullptr;
+	       l++, count++)
+	    {
+	      if (count != 0)
+		buffer += ", ";
+	      buffer = buffer + '"' + l->literal + '"';
+	    }
+	  if (count > 1)
+	    error_no_arg
+	      (string_printf (_("integer to set it to, or one of: %s"),
+			      buffer.c_str ()).c_str ());
+	  else
+	    error_no_arg
+	      (string_printf (_("integer to set it to, or %s"),
+			      buffer.c_str ()).c_str ());
+	}
+    }
 
-  if (*arg == nullptr || **arg == '\0')
-    error_no_arg (_("integer to set it to, or \"unlimited\""));
+  if (!get_literal_val (val, extra_literals, arg, expression))
+    {
+      if (expression)
+	val = parse_and_eval_long (*arg);
+      else
+	val = get_ulongest (arg);
 
-  if (is_unlimited_literal (arg, expression))
-    val = -1;
-  else if (expression)
-    val = parse_and_eval_long (*arg);
-  else
-    val = get_ulongest (arg);
+      enum tribool allowed = TRIBOOL_UNKNOWN;
+      if (extra_literals != nullptr)
+	{
+	  for (const literal_def *l = extra_literals;
+	       l->literal != nullptr;
+	       l++)
+	    if (val == l->val)
+	      {
+		allowed = l->allow ? TRIBOOL_TRUE : TRIBOOL_FALSE;
+		val = l->use;
+		break;
+	      }
+	    else if (val == l->use)
+	      {
+		allowed = TRIBOOL_FALSE;
+		break;
+	      }
+	}
 
-  if (val > INT_MAX)
-    error (_("integer %s out of range"), plongest (val));
-  else if (val < -1)
-    error (_("only -1 is allowed to set as unlimited"));
+      if (allowed == TRIBOOL_UNKNOWN)
+	{
+	  if (var_type == var_pinteger && val < 0)
+	    error (_("only -1 is allowed to set as unlimited"));
+	  else if (val > UINT_MAX || val < INT_MIN
+		   || (var_type == var_uinteger && val < 0)
+		   || (var_type == var_integer && val > INT_MAX)
+		   || (var_type == var_pinteger && val > INT_MAX))
+	    allowed = TRIBOOL_FALSE;
+	}
+      if (allowed == TRIBOOL_FALSE)
+	error (_("integer %s out of range"), plongest (val));
+    }
 
   return val;
 }
@@ -405,41 +429,18 @@ do_set_command (const char *arg, int fro
       option_changed = c->var->set<enum auto_boolean> (parse_auto_binary_operation (arg));
       break;
     case var_uinteger:
-    case var_zuinteger:
       option_changed
-	= c->var->set<unsigned int> (parse_cli_var_uinteger (c->var->type (),
-							     &arg, true));
+	= c->var->set<unsigned int> (parse_cli_var_integer (c->var->type (),
+							    c->var->
+							    extra_literals (),
+							    &arg, true));
       break;
     case var_integer:
-    case var_zinteger:
-      {
-	LONGEST val;
-
-	if (*arg == '\0')
-	  {
-	    if (c->var->type () == var_integer)
-	      error_no_arg (_("integer to set it to, or \"unlimited\""));
-	    else
-	      error_no_arg (_("integer to set it to"));
-	  }
-
-	if (c->var->type () == var_integer && is_unlimited_literal (&arg, true))
-	  val = 0;
-	else
-	  val = parse_and_eval_long (arg);
-
-	if (val == 0 && c->var->type () == var_integer)
-	  val = INT_MAX;
-	else if (val < INT_MIN
-		 /* For var_integer, don't let the user set the value
-		    to INT_MAX directly, as that exposes an
-		    implementation detail to the user interface.  */
-		 || (c->var->type () == var_integer && val >= INT_MAX)
-		 || (c->var->type () == var_zinteger && val > INT_MAX))
-	  error (_("integer %s out of range"), plongest (val));
-
-	option_changed = c->var->set<int> (val);
-      }
+    case var_pinteger:
+      option_changed
+	= c->var->set<int> (parse_cli_var_integer (c->var->type (),
+						   c->var->extra_literals (),
+						   &arg, true));
       break;
     case var_enum:
       {
@@ -454,10 +455,6 @@ do_set_command (const char *arg, int fro
 	option_changed = c->var->set<const char *> (match);
       }
       break;
-    case var_zuinteger_unlimited:
-      option_changed = c->var->set<int>
-	(parse_cli_var_zuinteger_unlimited (&arg, true));
-      break;
     default:
       error (_("gdb internal error: bad var_type in do_setshow_command"));
     }
@@ -551,7 +548,6 @@ do_set_command (const char *arg, int fro
 	  }
 	  break;
 	case var_uinteger:
-	case var_zuinteger:
 	  {
 	    char s[64];
 
@@ -560,8 +556,7 @@ do_set_command (const char *arg, int fro
 	  }
 	  break;
 	case var_integer:
-	case var_zinteger:
-	case var_zuinteger_unlimited:
+	case var_pinteger:
 	  {
 	    char s[64];
 
@@ -623,36 +618,32 @@ get_setshow_command_value_string (const
 	}
       break;
     case var_uinteger:
-    case var_zuinteger:
-      {
-	const unsigned int value = var.get<unsigned int> ();
-
-	if (var.type () == var_uinteger
-	    && value == UINT_MAX)
-	  stb.puts ("unlimited");
-	else
-	  stb.printf ("%u", value);
-      }
-      break;
     case var_integer:
-    case var_zinteger:
+    case var_pinteger:
       {
-	const int value = var.get<int> ();
+	bool printed = false;
+	const LONGEST value
+	  = (var.type () == var_uinteger
+	     ? static_cast<LONGEST> (var.get<unsigned int> ())
+	     : static_cast<LONGEST> (var.get<int> ()));
 
-	if (var.type () == var_integer
-	    && value == INT_MAX)
-	  stb.puts ("unlimited");
-	else
-	  stb.printf ("%d", value);
-      }
-      break;
-    case var_zuinteger_unlimited:
-      {
-	const int value = var.get<int> ();
-	if (value == -1)
-	  stb.puts ("unlimited");
-	else
-	  stb.printf ("%d", value);
+	if (var.extra_literals () != nullptr)
+	  for (const literal_def *l = var.extra_literals ();
+	       l->literal != nullptr;
+	       l++)
+	    if (value == l->use)
+	      {
+		stb.puts (l->literal);
+		printed = true;
+		break;
+	      }
+	if (!printed)
+	  {
+	    if (var.type () == var_uinteger)
+	      stb.printf ("%u", static_cast<const unsigned int> (value));
+	    else
+	      stb.printf ("%d", static_cast<const int> (value));
+	  }
       }
       break;
     default:
Index: src/gdb/cli/cli-setshow.h
===================================================================
--- src.orig/gdb/cli/cli-setshow.h
+++ src/gdb/cli/cli-setshow.h
@@ -29,21 +29,19 @@ extern int parse_cli_boolean_value (cons
    past a successfully parsed value.  */
 extern int parse_cli_boolean_value (const char **arg);
 
-/* Parse ARG, an option to a var_uinteger or var_zuinteger variable.
-   Either returns the parsed value on success or throws an error.  If
-   EXPRESSION is true, *ARG is parsed as an expression; otherwise, it
-   is parsed with get_ulongest.  It's not possible to parse the
+/* Parse ARG, an option to a var_uinteger, var_integer or var_pinteger
+   variable.  Return the parsed value on success or throw an error.  If
+   EXTRA_LITERALS is non-null, then interpret those literals accordingly.
+   If EXPRESSION is true, *ARG is parsed as an expression; otherwise,
+   it is parsed with get_ulongest.  It's not possible to parse the
    integer as an expression when there may be valid input after the
    integer, such as when parsing command options.  E.g., "print
    -elements NUMBER -obj --".  In such case, parsing as an expression
    would parse "-obj --" as part of the expression as well.  */
-extern unsigned int parse_cli_var_uinteger (var_types var_type,
-					    const char **arg,
-					    bool expression);
-
-/* Like parse_cli_var_uinteger, for var_zuinteger_unlimited.  */
-extern int parse_cli_var_zuinteger_unlimited (const char **arg,
-					      bool expression);
+extern LONGEST parse_cli_var_integer (var_types var_type,
+				      const literal_def *extra_literals,
+				      const char **arg,
+				      bool expression);
 
 /* Parse ARG, an option to a var_enum variable.  ENUM is a
    null-terminated array of possible values. Either returns the parsed
Index: src/gdb/command.h
===================================================================
--- src.orig/gdb/command.h
+++ src/gdb/command.h
@@ -84,16 +84,18 @@ typedef enum var_types
        value.  */
     var_auto_boolean,
 
-    /* Unsigned Integer.  *VAR is an unsigned int.  The user can type
-       0 to mean "unlimited", which is stored in *VAR as UINT_MAX.  */
+    /* Unsigned Integer.  *VAR is an unsigned int.  In the Guile and Python
+       APIs 0 means unlimited, which is stored in *VAR as UINT_MAX.  */
     var_uinteger,
 
-    /* Like var_uinteger but signed.  *VAR is an int.  The user can
-       type 0 to mean "unlimited", which is stored in *VAR as
-       INT_MAX.  The only remaining use of it is the Python API.
-       Don't use it elsewhere.  */
+    /* Like var_uinteger but signed.  *VAR is an int.  In the Guile and
+       Python APIs 0 means unlimited, which is stored in *VAR as INT_MAX.  */
     var_integer,
 
+    /* Like var_integer but negative numbers are not allowed,
+       except for special values.  *VAR is an int.  */
+    var_pinteger,
+
     /* String which the user enters with escapes (e.g. the user types
        \n and it is a real newline in the stored string).
        *VAR is a std::string, "" if the string is empty.  */
@@ -106,15 +108,16 @@ typedef enum var_types
     var_optional_filename,
     /* String which stores a filename.  (*VAR) is a std::string.  */
     var_filename,
-    /* ZeroableInteger.  *VAR is an int.  Like var_integer except
-       that zero really means zero.  */
+    /* Like var_integer.  *VAR is an int.  The only remaining uses
+       of it are the Guile and Python APIs.  Don't use it elsewhere.  */
     var_zinteger,
-    /* ZeroableUnsignedInteger.  *VAR is an unsigned int.  Zero really
-       means zero.  */
+    /* Like var_uinteger.  *VAR is an unsigned int.  The only remaining
+       uses of it are the Guile and Python APIs.  Don't use it elsewhere.  */
     var_zuinteger,
-    /* ZeroableUnsignedInteger with unlimited value.  *VAR is an int,
-       but its range is [0, INT_MAX].  -1 stands for unlimited and
-       other negative numbers are not allowed.  */
+    /* Like var_pinteger.  *VAR is an int, but its range is [-1, INT_MAX].
+       -1 stands for unlimited and other negative numbers are not allowed.
+       The only remaining uses of it are the Guile and Python APIs.  Don't
+       use it elsewhere.  */
     var_zuinteger_unlimited,
     /* Enumerated type.  Can only have one of the specified values.
        *VAR is a char pointer to the name of the element that we
@@ -123,6 +126,22 @@ typedef enum var_types
   }
 var_types;
 
+/* A structure describing an extra literal accepted and shown in place
+   of a number.  */
+typedef struct literal_defs
+  {
+    /* The literal to define, e.g. "unlimited".  */
+    const char *literal;
+    /* A number optionally accepted that stands for the literal.  */
+    LONGEST val;
+    /* The number to substitute internally for LITERAL or VAL;
+       the use of this number is not allowed (unless the same as VAL).  */
+    LONGEST use;
+    /* True if the use of VAL is allowed; otherwise only the literal is.  */
+    bool allow;
+  }
+literal_def;
+
 /* Return true if a setting of type VAR_TYPE is backed with type T.
 
    This function is left without definition intentionally.  This template is
@@ -153,15 +172,14 @@ inline bool var_type_uses<enum auto_bool
 template<>
 inline bool var_type_uses<unsigned int> (var_types t)
 {
-  return (t == var_uinteger || t == var_zinteger || t == var_zuinteger);
+  return t == var_uinteger;
 }
 
 /* Return true if a setting of type T is backed by an int variable.  */
 template<>
 inline bool var_type_uses<int> (var_types t)
 {
-  return (t == var_integer || t == var_zinteger
-	  || t == var_zuinteger_unlimited);
+  return t == var_integer || t == var_pinteger;
 }
 
 /* Return true if a setting of type T is backed by a std::string variable.  */
@@ -233,6 +251,7 @@ struct setting
   struct erased_args
   {
     void *var;
+    const void *extra_literals;
     erased_func setter;
     erased_func getter;
   };
@@ -240,6 +259,7 @@ struct setting
   template<typename T>
   static erased_args erase_args (var_types var_type,
 				 T *var,
+				 const literal_def *extra_literals,
 				 typename setting_func_types<T>::set set_setting_func,
 				 typename setting_func_types<T>::get get_setting_func)
   {
@@ -254,6 +274,7 @@ struct setting
 
     return {
 	var,
+	extra_literals,
 	reinterpret_cast<erased_func> (set_setting_func),
 	reinterpret_cast<erased_func> (get_setting_func)
     };
@@ -265,6 +286,7 @@ struct setting
   setting (var_types var_type, const erased_args &args)
     : m_var_type (var_type),
       m_var (args.var),
+      m_extra_literals (args.extra_literals),
       m_getter (args.getter),
       m_setter (args.setter)
   {
@@ -295,6 +317,10 @@ struct setting
   var_types type () const
   { return m_var_type; }
 
+  /* Access any extra literals accepted.  */
+  const literal_def *extra_literals () const
+  { return static_cast<const literal_def *> (m_extra_literals); }
+
   /* Return the current value.
 
      The template parameter T is the type of the variable used to store the
@@ -357,6 +383,9 @@ struct setting
      non-nullptr.  */
   void *m_var = nullptr;
 
+  /* Any extra literals accepted.  */
+  const void *m_extra_literals = nullptr;
+
   /* Pointer to a user provided getter.  */
   erased_func m_getter = nullptr;
 
@@ -652,6 +681,11 @@ typedef void (show_value_ftype) (struct
    instead print the value out directly.  */
 extern show_value_ftype deprecated_show_value_hack;
 
+/* Various sets of extra literals accepted.  */
+extern const literal_def integer_unlimited_literals[];
+extern const literal_def uinteger_unlimited_literals[];
+extern const literal_def zuinteger_unlimited_literals[];
+
 extern set_show_commands add_setshow_enum_cmd
   (const char *name, command_class theclass, const char *const *enumlist,
    const char **var, const char *set_doc, const char *show_doc,
@@ -748,6 +782,20 @@ extern set_show_commands add_setshow_opt
    cmd_list_element **show_list);
 
 extern set_show_commands add_setshow_integer_cmd
+  (const char *name, command_class theclass, int *var,
+   const literal_def *extra_literals, const char *set_doc,
+   const char *show_doc, const char *help_doc, cmd_func_ftype *set_func,
+   show_value_ftype *show_func, cmd_list_element **set_list,
+   cmd_list_element **show_list);
+
+extern set_show_commands add_setshow_integer_cmd
+  (const char *name, command_class theclass, const literal_def *extra_literals,
+   const char *set_doc, const char *show_doc, const char *help_doc,
+   setting_func_types<int>::set set_func,
+   setting_func_types<int>::get get_func, show_value_ftype *show_func,
+   cmd_list_element **set_list, cmd_list_element **show_list);
+
+extern set_show_commands add_setshow_integer_cmd
   (const char *name, command_class theclass, int *var, const char *set_doc,
    const char *show_doc, const char *help_doc, cmd_func_ftype *set_func,
    show_value_ftype *show_func, cmd_list_element **set_list,
@@ -760,6 +808,34 @@ extern set_show_commands add_setshow_int
    setting_func_types<int>::get get_func, show_value_ftype *show_func,
    cmd_list_element **set_list, cmd_list_element **show_list);
 
+extern set_show_commands add_setshow_pinteger_cmd
+  (const char *name, command_class theclass, int *var,
+   const literal_def *extra_literals, const char *set_doc,
+   const char *show_doc, const char *help_doc, cmd_func_ftype *set_func,
+   show_value_ftype *show_func, cmd_list_element **set_list,
+   cmd_list_element **show_list);
+
+extern set_show_commands add_setshow_pinteger_cmd
+  (const char *name, command_class theclass, const literal_def *extra_literals,
+   const char *set_doc, const char *show_doc, const char *help_doc,
+   setting_func_types<int>::set set_func,
+   setting_func_types<int>::get get_func, show_value_ftype *show_func,
+   cmd_list_element **set_list, cmd_list_element **show_list);
+
+extern set_show_commands add_setshow_uinteger_cmd
+  (const char *name, command_class theclass, unsigned int *var,
+   const literal_def *extra_literals,
+   const char *set_doc, const char *show_doc, const char *help_doc,
+   cmd_func_ftype *set_func, show_value_ftype *show_func,
+   cmd_list_element **set_list, cmd_list_element **show_list);
+
+extern set_show_commands add_setshow_uinteger_cmd
+  (const char *name, command_class theclass, const literal_def *extra_literals,
+   const char *set_doc, const char *show_doc, const char *help_doc,
+   setting_func_types<unsigned int>::set set_func,
+   setting_func_types<unsigned int>::get get_func, show_value_ftype *show_func,
+   cmd_list_element **set_list, cmd_list_element **show_list);
+
 extern set_show_commands add_setshow_uinteger_cmd
   (const char *name, command_class theclass, unsigned int *var,
    const char *set_doc, const char *show_doc, const char *help_doc,
Index: src/gdb/guile/scm-param.c
===================================================================
--- src.orig/gdb/guile/scm-param.c
+++ src/gdb/guile/scm-param.c
@@ -117,18 +117,33 @@ struct param_smob
 static setting
 make_setting (param_smob *s)
 {
-  if (var_type_uses<bool> (s->type))
-    return setting (s->type, &s->value.boolval);
-  else if (var_type_uses<int> (s->type))
-    return setting (s->type, &s->value.intval);
-  else if (var_type_uses<auto_boolean> (s->type))
-    return setting (s->type, &s->value.autoboolval);
-  else if (var_type_uses<unsigned int> (s->type))
-    return setting (s->type, &s->value.uintval);
-  else if (var_type_uses<std::string> (s->type))
-    return setting (s->type, s->value.stringval);
-  else if (var_type_uses<const char *> (s->type))
-    return setting (s->type, &s->value.cstringval);
+  enum var_types type = s->type;
+
+  switch (type)
+    {
+    case var_zinteger:
+      type = var_integer;
+      break;
+    case var_zuinteger:
+      type = var_uinteger;
+      break;
+    case var_zuinteger_unlimited:
+      type = var_pinteger;
+      break;
+    }
+
+  if (var_type_uses<bool> (type))
+    return setting (type, &s->value.boolval);
+  else if (var_type_uses<int> (type))
+    return setting (type, &s->value.intval);
+  else if (var_type_uses<auto_boolean> (type))
+    return setting (type, &s->value.autoboolval);
+  else if (var_type_uses<unsigned int> (type))
+    return setting (type, &s->value.uintval);
+  else if (var_type_uses<std::string> (type))
+    return setting (type, s->value.stringval);
+  else if (var_type_uses<const char *> (type))
+    return setting (type, &s->value.cstringval);
   else
     gdb_assert_not_reached ("unhandled var type");
 }
@@ -588,10 +603,6 @@ pascm_param_type_name (enum var_types pa
 static SCM
 pascm_param_value (const setting &var, int arg_pos, const char *func_name)
 {
-  /* Note: We *could* support var_integer here in case someone is trying to get
-     the value of a Python-created parameter (which is the only place that
-     still supports var_integer).  To further discourage its use we do not.  */
-
   switch (var.type ())
     {
     case var_string:
@@ -631,20 +642,35 @@ pascm_param_value (const setting &var, i
 	  return auto_keyword;
       }
 
-    case var_zuinteger_unlimited:
-      if (var.get<int> () == -1)
-	return unlimited_keyword;
-      gdb_assert (var.get<int> () >= 0);
-      /* Fall through.  */
-    case var_zinteger:
-      return scm_from_int (var.get<int> ());
-
     case var_uinteger:
-      if (var.get<unsigned int> ()== UINT_MAX)
-	return unlimited_keyword;
-      /* Fall through.  */
-    case var_zuinteger:
-      return scm_from_uint (var.get<unsigned int> ());
+    case var_integer:
+    case var_pinteger:
+      {
+	LONGEST value
+	  = (var.type () == var_uinteger
+	     ? static_cast<LONGEST> (var.get<unsigned int> ())
+	     : static_cast<LONGEST> (var.get<int> ()));
+
+	bool literal = false;
+	if (var.extra_literals () != nullptr)
+	  for (const literal_def *l = var.extra_literals ();
+	       l->literal != nullptr;
+	       l++)
+	    if (value == l->use)
+	      {
+		if (strcmp (l->literal, "unlimited") == 0)
+		  return unlimited_keyword;
+		value = l->val;
+		literal = true;
+	      }
+	if (var.type () == var_pinteger && !literal)
+	  gdb_assert (value >= 0);
+
+	if (var.type () == var_uinteger)
+	  return scm_from_uint (static_cast<const unsigned int> (value));
+	else
+	  return scm_from_int (static_cast<const int> (value));
+      }
 
     default:
       break;
@@ -666,14 +692,14 @@ pascm_set_param_value_x (param_smob *p_s
 {
   setting var = make_setting (p_smob);
 
-  switch (var.type ())
+  switch (p_smob->type)
     {
     case var_string:
     case var_string_noescape:
     case var_optional_filename:
     case var_filename:
       SCM_ASSERT_TYPE (scm_is_string (value)
-		       || (var.type () != var_filename
+		       || (p_smob->type != var_filename
 			   && gdbscm_is_false (value)),
 		       value, arg_pos, func_name,
 		       _("string or #f for non-PARAM_FILENAME parameters"));
@@ -739,8 +765,8 @@ pascm_set_param_value_x (param_smob *p_s
     case var_uinteger:
     case var_zuinteger:
     case var_zuinteger_unlimited:
-      if (var.type () == var_uinteger
-	  || var.type () == var_zuinteger_unlimited)
+      if (p_smob->type == var_uinteger
+	  || p_smob->type == var_zuinteger_unlimited)
 	{
 	  SCM_ASSERT_TYPE (gdbscm_is_bool (value)
 			   || scm_is_eq (value, unlimited_keyword),
@@ -748,7 +774,7 @@ pascm_set_param_value_x (param_smob *p_s
 			   _("integer or #:unlimited"));
 	  if (scm_is_eq (value, unlimited_keyword))
 	    {
-	      if (var.type () == var_uinteger)
+	      if (p_smob->type == var_uinteger)
 		var.set<unsigned int> (UINT_MAX);
 	      else
 		var.set<int> (-1);
@@ -761,12 +787,12 @@ pascm_set_param_value_x (param_smob *p_s
 			   _("integer"));
 	}
 
-      if (var.type () == var_uinteger
-	  || var.type () == var_zuinteger)
+      if (p_smob->type == var_uinteger
+	  || p_smob->type == var_zuinteger)
 	{
 	  unsigned int u = scm_to_uint (value);
 
-	  if (var.type () == var_uinteger && u == 0)
+	  if (p_smob->type == var_uinteger && u == 0)
 	    u = UINT_MAX;
 	  var.set<unsigned int> (u);
 	}
@@ -774,7 +800,7 @@ pascm_set_param_value_x (param_smob *p_s
 	{
 	  int i = scm_to_int (value);
 
-	  if (var.type () == var_zuinteger_unlimited && i < -1)
+	  if (p_smob->type == var_zuinteger_unlimited && i < -1)
 	    {
 	      gdbscm_out_of_range_error (func_name, arg_pos, value,
 					 _("must be >= -1"));
Index: src/gdb/maint-test-options.c
===================================================================
--- src.orig/gdb/maint-test-options.c
+++ src/gdb/maint-test-options.c
@@ -207,6 +207,7 @@ static const gdb::option::option_def tes
   gdb::option::uinteger_option_def<test_options_opts> {
     "uinteger",
     [] (test_options_opts *opts) { return &opts->uint_opt; },
+    uinteger_unlimited_literals,
     nullptr, /* show_cmd_cb */
     N_("A uinteger option."),
     nullptr, /* show_doc */
@@ -214,9 +215,10 @@ static const gdb::option::option_def tes
   },
 
   /* A zuinteger_unlimited option.  */
-  gdb::option::zuinteger_unlimited_option_def<test_options_opts> {
+  gdb::option::integer_option_def<test_options_opts> {
     "zuinteger-unlimited",
     [] (test_options_opts *opts) { return &opts->zuint_unl_opt; },
+    zuinteger_unlimited_literals,
     nullptr, /* show_cmd_cb */
     N_("A zuinteger-unlimited option."),
     nullptr, /* show_doc */
Index: src/gdb/python/py-param.c
===================================================================
--- src.orig/gdb/python/py-param.c
+++ src/gdb/python/py-param.c
@@ -96,18 +96,33 @@ struct parmpy_object
 static setting
 make_setting (parmpy_object *s)
 {
-  if (var_type_uses<bool> (s->type))
-    return setting (s->type, &s->value.boolval);
-  else if (var_type_uses<int> (s->type))
-    return setting (s->type, &s->value.intval);
-  else if (var_type_uses<auto_boolean> (s->type))
-    return setting (s->type, &s->value.autoboolval);
-  else if (var_type_uses<unsigned int> (s->type))
-    return setting (s->type, &s->value.uintval);
-  else if (var_type_uses<std::string> (s->type))
-    return setting (s->type, s->value.stringval);
-  else if (var_type_uses<const char *> (s->type))
-    return setting (s->type, &s->value.cstringval);
+  enum var_types type = s->type;
+
+  switch (type)
+    {
+    case var_zinteger:
+      type = var_integer;
+      break;
+    case var_zuinteger:
+      type = var_uinteger;
+      break;
+    case var_zuinteger_unlimited:
+      type = var_pinteger;
+      break;
+    }
+
+  if (var_type_uses<bool> (type))
+    return setting (type, &s->value.boolval);
+  else if (var_type_uses<int> (type))
+    return setting (type, &s->value.intval);
+  else if (var_type_uses<auto_boolean> (type))
+    return setting (type, &s->value.autoboolval);
+  else if (var_type_uses<unsigned int> (type))
+    return setting (type, &s->value.uintval);
+  else if (var_type_uses<std::string> (type))
+    return setting (type, s->value.stringval);
+  else if (var_type_uses<const char *> (type))
+    return setting (type, &s->value.cstringval);
   else
     gdb_assert_not_reached ("unhandled var type");
 }
Index: src/gdb/python/python.c
===================================================================
--- src.orig/gdb/python/python.c
+++ src/gdb/python/python.c
@@ -502,35 +502,34 @@ gdbpy_parameter_value (const setting &va
 	  Py_RETURN_NONE;
       }
 
-    case var_integer:
-      if (var.get<int> () == INT_MAX)
-	Py_RETURN_NONE;
-      /* Fall through.  */
-    case var_zinteger:
-      return gdb_py_object_from_longest (var.get<int> ()).release ();
-
-    case var_zuinteger_unlimited:
-      {
-	int val = var.get<int> ();
-
-	if (val == -1)
-	  Py_RETURN_NONE;
-	return gdb_py_object_from_longest (val).release ();
-      }
-
     case var_uinteger:
+    case var_integer:
+    case var_pinteger:
       {
-	unsigned int val = var.get<unsigned int> ();
+	LONGEST value
+	  = (var.type () == var_uinteger
+	     ? static_cast<LONGEST> (var.get<unsigned int> ())
+	     : static_cast<LONGEST> (var.get<int> ()));
 
-	if (val == UINT_MAX)
-	  Py_RETURN_NONE;
-	return gdb_py_object_from_ulongest (val).release ();
-      }
+	if (var.extra_literals () != nullptr)
+	  for (const literal_def *l = var.extra_literals ();
+	       l->literal != nullptr;
+	       l++)
+	    if (value == l->use)
+	      {
+		if (strcmp (l->literal, "unlimited") == 0)
+		  Py_RETURN_NONE;
+		value = l->val;
+	      }
 
-    case var_zuinteger:
-      {
-	unsigned int val = var.get<unsigned int> ();
-	return gdb_py_object_from_ulongest (val).release ();
+	if (var.type () == var_uinteger)
+	  return
+	    gdb_py_object_from_ulongest
+	      (static_cast<const unsigned int> (value)).release ();
+	else
+	  return
+	    gdb_py_object_from_longest
+	      (static_cast<const int> (value)).release ();
       }
     }
 
Index: src/gdb/valprint.c
===================================================================
--- src.orig/gdb/valprint.c
+++ src/gdb/valprint.c
@@ -2974,8 +2974,8 @@ using boolean_option_def
   = gdb::option::boolean_option_def<value_print_options>;
 using uinteger_option_def
   = gdb::option::uinteger_option_def<value_print_options>;
-using zuinteger_unlimited_option_def
-  = gdb::option::zuinteger_unlimited_option_def<value_print_options>;
+using integer_option_def
+  = gdb::option::integer_option_def<value_print_options>;
 
 /* Definitions of options for the "print" and "compile print"
    commands.  */
@@ -3011,15 +3011,17 @@ static const gdb::option::option_def val
   uinteger_option_def {
     "elements",
     [] (value_print_options *opt) { return &opt->print_max; },
+    uinteger_unlimited_literals,
     show_print_max, /* show_cmd_cb */
     N_("Set limit on string chars or array elements to print."),
     N_("Show limit on string chars or array elements to print."),
     N_("\"unlimited\" causes there to be no limit."),
   },
 
-  zuinteger_unlimited_option_def {
+  integer_option_def {
     "max-depth",
     [] (value_print_options *opt) { return &opt->max_depth; },
+    zuinteger_unlimited_literals,
     show_print_max_depth, /* show_cmd_cb */
     N_("Set maximum print depth for nested structures, unions and arrays."),
     N_("Show maximum print depth for nested structures, unions, and arrays."),
@@ -3079,6 +3081,7 @@ pretty-printers for that value.")
   uinteger_option_def {
     "repeats",
     [] (value_print_options *opt) { return &opt->repeat_count_threshold; },
+    uinteger_unlimited_literals,
     show_repeat_count_threshold, /* show_cmd_cb */
     N_("Set threshold for repeated print elements."),
     N_("Show threshold for repeated print elements."),