Make 'text-property-default-nonsticky' buffer-local when set

* src/textprop.c (syms_of_textprop)
<text-property-default-nonsticky>: Make buffer-local when set.
(Bug#76445)

* etc/symbol-releases.eld: Add text-property-default-nonsticky.

* etc/NEWS:
* doc/lispref/text.texi (Sticky Properties): Document the change.

4 files changed, 12 insertions, 4 deletions

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index bada8bd734b..90aa45e8501 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -4135,10 +4135,10 @@ list, properties are rear-sticky @emph{unless} their names are in the
 list.
 
 @defvar text-property-default-nonsticky
-This variable holds an alist which defines the default rear-stickiness
-of various text properties.  Each element has the form
-@code{(@var{property} . @var{nonstickiness})}, and it defines the
-stickiness of a particular text property, @var{property}.
+This buffer-local variable holds an alist which defines the default
+rear-stickiness of various text properties in the buffer.  Each element
+has the form @code{(@var{property} . @var{nonstickiness})}, and it
+defines the stickiness of a particular text property, @var{property}.
 
 If @var{nonstickiness} is non-@code{nil}, this means that the property
 @var{property} is rear-nonsticky by default.  Since all properties are
diff --git a/etc/NEWS b/etc/NEWS
index bd7c678b8da..a03ffe91ab9 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1306,6 +1306,11 @@ An old alternative name (without the first 'e') has been removed.
 +++
 ** 'read-directory-name' now accepts an optional PREDICATE argument.
 
++++
+** 'text-property-default-nonsticky' is now buffer-local.
+This variable now becomes buffer-local when set.  Use 'setq-default' in
+(the unlikely) case you want to change the global value.
+
 ---
 ** All the digit characters now have the 'digit' category.
 All the characters whose Unicode general-category is Nd now have the
diff --git a/etc/symbol-releases.eld b/etc/symbol-releases.eld
index 645ab77972d..41200581be5 100644
--- a/etc/symbol-releases.eld
+++ b/etc/symbol-releases.eld
@@ -44,6 +44,7 @@
  ("22.1" fun version<)
  ("22.1" fun version<=)
  ("22.1" fun read-number)
+ ("21.1" var text-property-default-nonsticky)
 
 ;; Since much of early Emacs source history is lost, these versions are
 ;; conservative estimates: the actual version of first appearance may very
diff --git a/src/textprop.c b/src/textprop.c
index 30c26ce4809..8fdaafccede 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -2427,6 +2427,7 @@ inherits it if NONSTICKINESS is nil.  The `front-sticky' and
      by default.  */
   Vtext_property_default_nonsticky
     = list2 (Fcons (Qsyntax_table, Qt), Fcons (Qdisplay, Qt));
+  Fmake_variable_buffer_local (Qtext_property_default_nonsticky);
 
   interval_insert_behind_hooks = Qnil;
   interval_insert_in_front_hooks = Qnil;
@@ -2444,6 +2445,7 @@ inherits it if NONSTICKINESS is nil.  The `front-sticky' and
   DEFSYM (Qlocal_map, "local-map");
   DEFSYM (Qfront_sticky, "front-sticky");
   DEFSYM (Qrear_nonsticky, "rear-nonsticky");
+  DEFSYM (Qtext_property_default_nonsticky, "text-property-default-nonsticky");
   DEFSYM (Qmouse_face, "mouse-face");
   DEFSYM (Qminibuffer_prompt, "minibuffer-prompt");