vim-patch:9.1.0565: Stop directory doesn't work properly in 'tags'

Problem:  Stop directory doesn't work properly in 'tags'.
          (Jesse Pavel)
Solution: Also move the stop directory forward by one byte.
          (zeertzjq)

This doesn't support relative stop directories yet, as they are not
supported in other places like findfile() either.

fixes: vim/vim#15200
related: vim/vim#15202

https://github.com/vim/vim/commit/68819afb2cdd0f44baa080db589e1d8f77099e5f

2 files changed, 27 insertions, 0 deletions

diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index 90269c776e..cc7ff070c2 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -2583,6 +2583,10 @@ int get_tagfname(tagname_T *tnp, int first, char *buf)
       // move the filename one char forward and truncate the
       // filepath with a NUL
       filename = path_tail(buf);
+      if (r_ptr != NULL) {
+        STRMOVE(r_ptr + 1, r_ptr);
+        r_ptr++;
+      }
       STRMOVE(filename + 1, filename);
       *filename++ = NUL;
 
diff --git a/test/old/testdir/test_taglist.vim b/test/old/testdir/test_taglist.vim
index 75d28c3ec4..d74bd1e0e1 100644
--- a/test/old/testdir/test_taglist.vim
+++ b/test/old/testdir/test_taglist.vim
@@ -135,6 +135,29 @@ func Test_tagsfile_without_trailing_newline()
   set tags&
 endfunc
 
+" Check that specifying a stop directory in 'tags' works properly.
+func Test_tagfiles_stopdir()
+  let save_cwd = getcwd()
+
+  call mkdir('Xtagsdir1/Xtagsdir2/Xtagsdir3', 'pR')
+  call writefile([], 'Xtagsdir1/Xtags', 'D')
+
+  cd Xtagsdir1/
+  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  call assert_equal(1, len(tagfiles()))
+
+  cd Xtagsdir2/
+  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  call assert_equal(1, len(tagfiles()))
+
+  cd Xtagsdir3/
+  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  call assert_equal(0, len(tagfiles()))
+
+  set tags&
+  call chdir(save_cwd)
+endfunc
+
 " Test for ignoring comments in a tags file
 func Test_tagfile_ignore_comments()
   call writefile([