feat(jumplist): allow opting out of removing unloaded buffers (#30419)

Problem:  Cannot opt out of removing unloaded buffers from the jumplist.
Solution: Only enable that with "clean" flag in 'jumpoptions'.

test/functional/editor/jump_spec.lua

@@ -194,7 +194,7 @@ describe("jumpoptions=stack behaves like 'tagstack'", function()
   end)
 end)
 
-describe('buffer deletion', function()
+describe('buffer deletion with jumpoptions+=clean', function()
   local base_file = 'Xtest-functional-buffer-deletion'
   local file1 = base_file .. '1'
   local file2 = base_file .. '2'
@@ -227,6 +227,12 @@ describe('buffer deletion', function()
     command('edit ' .. file3)
   end)
 
+  after_each(function()
+    os.remove(file1)
+    os.remove(file2)
+    os.remove(file3)
+  end)
+
   it('deletes jump list entries when the current buffer is deleted', function()
     command('edit ' .. file1)
 
@@ -319,6 +325,44 @@ describe('buffer deletion', function()
   end)
 end)
 
+describe('buffer deletion with jumpoptions-=clean', function()
+  local base_file = 'Xtest-functional-buffer-deletion'
+  local file1 = base_file .. '1'
+  local file2 = base_file .. '2'
+  local base_content = 'text'
+  local content1 = base_content .. '1'
+  local content2 = base_content .. '2'
+
+  before_each(function()
+    clear()
+    command('clearjumps')
+    command('set jumpoptions-=clean')
+
+    write_file(file1, content1, false, false)
+    write_file(file2, content2, false, false)
+
+    command('edit ' .. file1)
+    command('edit ' .. file2)
+  end)
+
+  after_each(function()
+    os.remove(file1)
+    os.remove(file2)
+  end)
+
+  it('Ctrl-O reopens previous buffer with :bunload or :bdelete #28968', function()
+    eq(file2, fn.bufname(''))
+    command('bunload')
+    eq(file1, fn.bufname(''))
+    feed('<C-O>')
+    eq(file2, fn.bufname(''))
+    command('bdelete')
+    eq(file1, fn.bufname(''))
+    feed('<C-O>')
+    eq(file2, fn.bufname(''))
+  end)
+end)
+
 describe('jumpoptions=view', function()
   local file1 = 'Xtestfile-functional-editor-jumps'
   local file2 = 'Xtestfile-functional-editor-jumps-2'

test/old/testdir/setup.vim

@@ -13,6 +13,7 @@ if exists('s:did_load')
   set laststatus=1
   set listchars=eol:$
   set joinspaces
+  set jumpoptions=
   set mousemodel=extend
   set nohidden nosmarttab noautoindent noautoread noruler noshowcmd
   set nohlsearch noincsearch