jumplist: avoid extra tail entry #9805

fixes #9775

runtime/doc/vim_diff.txt

@@ -319,6 +319,9 @@ Macro/|recording| behavior
   macros and 'keymap' at the same time. This also means you can use |:imap| on
   the results of keys from 'keymap'.
 
+Motion:
+  The |jumplist| avoids useless/phantom jumps.
+
 Normal commands:
   |Q| is the same as |gQ|
 

src/nvim/mark.c

@@ -1188,9 +1188,23 @@ void cleanup_jumplist(void)
       xfree(curwin->w_jumplist[from].fname);
     }
   }
-  if (curwin->w_jumplistidx == curwin->w_jumplistlen)
+  if (curwin->w_jumplistidx == curwin->w_jumplistlen) {
     curwin->w_jumplistidx = to;
+  }
   curwin->w_jumplistlen = to;
+
+  // When pointer is below last jump, remove the jump if it matches the current
+  // line.  This avoids useless/phantom jumps. #9805
+  if (curwin->w_jumplistlen
+      && curwin->w_jumplistidx == curwin->w_jumplistlen) {
+    const xfmark_T *fm_last = &curwin->w_jumplist[curwin->w_jumplistlen - 1];
+    if (fm_last->fmark.fnum == curbuf->b_fnum
+        && fm_last->fmark.mark.lnum == curwin->w_cursor.lnum) {
+      xfree(fm_last->fname);
+      curwin->w_jumplistlen--;
+      curwin->w_jumplistidx--;
+    }
+  }
 }
 
 /*

src/nvim/shada.c

@@ -2739,8 +2739,8 @@ static ShaDaWriteResult shada_write(ShaDaWriteDef *const sd_writer,
 
   // Initialize jump list
   const void *jump_iter = NULL;
-  setpcmark();
   cleanup_jumplist();
+  setpcmark();
   do {
     xfmark_T fm;
     jump_iter = mark_jumplist_iter(jump_iter, curwin, &fm);

test/functional/normal/jump_spec.lua

@@ -0,0 +1,48 @@
+local helpers = require('test.functional.helpers')(after_each)
+
+local clear = helpers.clear
+local command = helpers.command
+local eq = helpers.eq
+local funcs = helpers.funcs
+local feed = helpers.feed
+local write_file = helpers.write_file
+
+describe('jumplist', function()
+  local fname1 = 'Xtest-functional-normal-jump'
+  local fname2 = fname1..'2'
+  before_each(clear)
+  after_each(function()
+    os.remove(fname1)
+    os.remove(fname2)
+  end)
+
+  it('does not add a new entry on startup', function()
+    eq('\n jump line  col file/text\n>', funcs.execute('jumps'))
+  end)
+
+  it('does not require two <C-O> strokes to jump back', function()
+    write_file(fname1, 'first file contents')
+    write_file(fname2, 'second file contents')
+
+    command('args '..fname1..' '..fname2)
+    local buf1 = funcs.bufnr(fname1)
+    local buf2 = funcs.bufnr(fname2)
+
+    command('next')
+    feed('<C-O>')
+    eq(buf1, funcs.bufnr('%'))
+
+    command('first')
+    command('snext')
+    feed('<C-O>')
+    eq(buf1, funcs.bufnr('%'))
+    feed('<C-I>')
+    eq(buf2, funcs.bufnr('%'))
+    feed('<C-O>')
+    eq(buf1, funcs.bufnr('%'))
+
+    command('drop '..fname2)
+    feed('<C-O>')
+    eq(buf1, funcs.bufnr('%'))
+  end)
+end)

test/functional/shada/marks_spec.lua

@@ -189,9 +189,6 @@ describe('ShaDa support code', function()
     eq(1, nvim_current_line())
     nvim_command('execute "normal! \\<C-o>"')
     eq(testfilename, funcs.bufname('%'))
-    eq(1, nvim_current_line())
-    nvim_command('execute "normal! \\<C-o>"')
-    eq(testfilename, funcs.bufname('%'))
     eq(2, nvim_current_line())
     nvim_command('execute "normal! \\<C-o>"')
     eq(testfilename_2, funcs.bufname('%'))
@@ -199,6 +196,9 @@ describe('ShaDa support code', function()
     nvim_command('execute "normal! \\<C-o>"')
     eq(testfilename_2, funcs.bufname('%'))
     eq(2, nvim_current_line())
+    nvim_command('execute "normal! \\<C-o>"')
+    eq(testfilename_2, funcs.bufname('%'))
+    eq(2, nvim_current_line())
   end)
 
   it('is able to dump and restore change list', function()

test/functional/shada/merging_spec.lua

@@ -912,12 +912,11 @@ describe('ShaDa jumps support code', function()
     eq('', curbufmeths.get_name())
     eq('\n'
        .. ' jump line  col file/text\n'
-       .. '   6     2    0 ' .. mock_file_path .. 'c\n'
-       .. '   5     2    0 ' .. mock_file_path .. 'd\n'
-       .. '   4     3    0 ' .. mock_file_path .. 'd\n'
-       .. '   3     2    0 ' .. mock_file_path .. 'e\n'
-       .. '   2     2    0 ' .. mock_file_path .. 'f\n'
-       .. '   1     1    0 \n'
+       .. '   5     2    0 ' .. mock_file_path .. 'c\n'
+       .. '   4     2    0 ' .. mock_file_path .. 'd\n'
+       .. '   3     3    0 ' .. mock_file_path .. 'd\n'
+       .. '   2     2    0 ' .. mock_file_path .. 'e\n'
+       .. '   1     2    0 ' .. mock_file_path .. 'f\n'
        .. '>', redir_exec('jumps'))
   end)