From 7313d60a163b66af039efc69046e4df4dff21457 Mon Sep 17 00:00:00 2001
From: Stefan Kangas <stefan@marxist.se>
Date: Sat, 25 Sep 2021 01:15:49 +0200
Subject: [PATCH 1/2] New :type natnum for defcustom

* lisp/wid-edit.el (natnum): New widget type.  (Bug#15809)
* doc/lispref/customize.texi (Simple Types): Document it.
---
 doc/lispref/customize.texi | 3 +++
 etc/NEWS                   | 5 +++++
 lisp/wid-edit.el           | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/doc/lispref/customize.texi b/doc/lispref/customize.texi
index bc35982c17..b93b8bc015 100644
--- a/doc/lispref/customize.texi
+++ b/doc/lispref/customize.texi
@@ -594,6 +594,9 @@ Simple Types
 @item integer
 The value must be an integer.
 
+@item natnum
+The value must be a nonnegative integer.
+
 @item number
 The value must be a number (floating point or integer).
 
diff --git a/etc/NEWS b/etc/NEWS
index c266dddafa..b2e7331517 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -3724,6 +3724,11 @@ instead of only becoming available after doing (for instance)
 ---
 ** ':safe' settings in 'defcustom' are now propagated to the loaddefs files.
 
++++
+** New ':type' for 'defcustom' for nonnegative integers.
+The new 'natnum' type can be used for options that should be
+nonnegative integers.
+
 +++
 ** ERT can now output more verbose test failure reports.
 If the 'EMACS_TEST_VERBOSE' environment variable is set, failure
diff --git a/lisp/wid-edit.el b/lisp/wid-edit.el
index ab358da7e3..72353b9190 100644
--- a/lisp/wid-edit.el
+++ b/lisp/wid-edit.el
@@ -3644,6 +3644,13 @@ 'integer
   :type-error "This field should contain an integer"
   :match-alternatives '(integerp))
 
+(define-widget 'natnum 'restricted-sexp
+  "A nonnegative integer."
+  :tag "Integer (positive)"
+  :value 0
+  :type-error "This field should contain a nonnegative integer"
+  :match-alternatives '(natnump))
+
 (define-widget 'number 'restricted-sexp
   "A number (floating point or integer)."
   :tag "Number"
-- 
2.30.2