fix(wininfo): when freeing windows, free the lowest priority wininfo

On master (and also before #31539) closing a window could cause the
used wininfo for a buffer to change. This is due to always removing the
previous NULL wininfo when deleting a window, even if that wininfo had
higher priority than the the deleted window's own wininfo.

Instead delete the wininfo with lowest priority. This retains the memory
saving efect while not affecting the effective value of window options
and so on.

1 files changed, 42 insertions, 0 deletions

diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 92999f383a..5d7dab2a7e 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -488,6 +488,48 @@ describe('API/win', function()
       assert_alive()
     end)
 
+    describe('after closing', function()
+      local buf, win0, win1, win2
+
+      before_each(function()
+        win0 = api.nvim_get_current_win()
+        command('new')
+        buf = api.nvim_get_current_buf()
+        win1 = api.nvim_get_current_win()
+        command('set numberwidth=10')
+        command('split')
+        win2 = api.nvim_get_current_win()
+        command('set numberwidth=15')
+        command('enew')
+        api.nvim_set_current_win(win1)
+        command('normal ix')
+        command('enew')
+        api.nvim_set_current_win(win0)
+        eq(4, api.nvim_get_option_value('numberwidth', {}))
+      end)
+
+      -- at this point buffer `buf` is current in no windows. Closing shouldn't affect its defaults
+      it('0 windows', function()
+        api.nvim_set_current_buf(buf)
+        eq(10, api.nvim_get_option_value('numberwidth', {}))
+      end)
+
+      it('1 window', function()
+        api.nvim_win_close(win1, false)
+
+        api.nvim_set_current_buf(buf)
+        eq(10, api.nvim_get_option_value('numberwidth', {}))
+      end)
+
+      it('2 windows', function()
+        api.nvim_win_close(win1, false)
+        api.nvim_win_close(win2, false)
+
+        api.nvim_set_current_buf(buf)
+        eq(10, api.nvim_get_option_value('numberwidth', {}))
+      end)
+    end)
+
     it('returns values for unset local options', function()
       eq(-1, api.nvim_get_option_value('scrolloff', { win = 0, scope = 'local' }))
     end)