emacs-28 f02944f5a1: Prevent GC of window referenced from EmacsScroller

[Eli Zaretskii]

branch: emacs-28
commit f02944f5a1ad18ceed4ae40a0fbbdddc981b4893
Author: Gerd Moellmann <gerd.moellmann@gmail.com>
Commit: Eli Zaretskii <eliz@gnu.org>

    Prevent GC of window referenced from EmacsScroller
    
    * src/nsterm.m (EmacsScroller.mark, mark_nsterm): New functions.
    * src/nsterm.h (EmacsScroller.mark, mark_nsterm): Declare.
    * src/alloc.c (garbage_collect) [MAVE_NS]: Call mark_nsterm.
    (Bug#56095)
    
    (cherry picked from commit 5f1bd872478927ad4bc635502e74628d39885286)
---
 src/alloc.c  |  5 +++++
 src/nsterm.h |  4 ++++
 src/nsterm.m | 30 ++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/src/alloc.c b/src/alloc.c
index 5ad8097394..1fe5b8f3fb 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -6145,6 +6145,11 @@ garbage_collect (void)
   mark_fringe_data ();
 #endif
 
+
+#ifdef HAVE_NS
+  mark_nsterm ();
+#endif
+
   /* Everything is now marked, except for the data in font caches,
      undo lists, and finalizers.  The first two are compacted by
      removing an items which aren't reachable otherwise.  */
diff --git a/src/nsterm.h b/src/nsterm.h
index 911539844a..4cfed10982 100644
--- a/src/nsterm.h
+++ b/src/nsterm.h
@@ -683,6 +683,7 @@ typedef id instancetype;
    int em_whole;
    }
 
+- (void) mark;
 - (instancetype) initFrame: (NSRect )r window: (Lisp_Object)win;
 - (void)setFrame: (NSRect)r;
 
@@ -1347,4 +1348,7 @@ enum NSWindowTabbingMode
 #define NSControlStateValueOff NSOffState
 #define NSBezelStyleRounded NSRoundedBezelStyle
 #endif
+
+extern void mark_nsterm (void);
+
 #endif /* HAVE_NS */
diff --git a/src/nsterm.m b/src/nsterm.m
index 40540c47be..1643ba5427 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -9039,6 +9039,16 @@ nswindow_orderedIndex_sort (id w1, id w2, void *c)
   return ret;
 }
 
+- (void) mark
+{
+  if (window)
+    {
+      Lisp_Object win;
+      XSETWINDOW (win, window);
+      mark_object (win);
+    }
+}
+
 
 - (void)resetCursorRects
 {
@@ -9780,6 +9790,26 @@ ns_xlfd_to_fontname (const char *xlfd)
   return ret;
 }
 
+void
+mark_nsterm (void)
+{
+  NSTRACE ("mark_nsterm");
+  Lisp_Object tail, frame;
+  FOR_EACH_FRAME (tail, frame)
+    {
+      struct frame *f = XFRAME (frame);
+      if (FRAME_NS_P (f))
+       {
+         NSArray *subviews = [[FRAME_NS_VIEW (f) superview] subviews];
+         for (int i = [subviews count] - 1; i >= 0; --i)
+           {
+             id scroller = [subviews objectAtIndex: i];
+             if ([scroller isKindOfClass: [EmacsScroller class]])
+                  [scroller mark];
+           }
+       }
+    }
+}
 
 void
 syms_of_nsterm (void)