Merge pull request #16951 from zeertzjq/vim-8.2.4007

2 files changed, 50 insertions, 8 deletions

diff --git a/src/nvim/ex_session.c b/src/nvim/ex_session.c
index a37cad9f2d..a6d6bcbb8d 100644
--- a/src/nvim/ex_session.c
+++ b/src/nvim/ex_session.c
@@ -338,14 +338,26 @@ static int put_view(FILE *fd, win_T *wp, int add_edit, unsigned *flagp, int curr
 
   // Edit the file.  Skip this when ":next" already did it.
   if (add_edit && (!did_next || wp->w_arg_idx_invalid)) {
-    char *fname_esc =
-      ses_escape_fname(ses_get_fname(wp->w_buffer, flagp), flagp);
-    //
-    // Load the file.
-    //
-    if (wp->w_buffer->b_ffname != NULL
-        && (!bt_nofile(wp->w_buffer)
-            || wp->w_buffer->terminal)) {
+    char *fname_esc = ses_escape_fname(ses_get_fname(wp->w_buffer, flagp), flagp);
+    if (bt_help(wp->w_buffer)) {
+      char *curtag = "";
+
+      // A help buffer needs some options to be set.
+      // First, create a new empty buffer with "buftype=help".
+      // Then ":help" will re-use both the buffer and the window and set
+      // the options, even when "options" is not in 'sessionoptions'.
+      if (0 < wp->w_tagstackidx && wp->w_tagstackidx <= wp->w_tagstacklen) {
+        curtag = (char *)wp->w_tagstack[wp->w_tagstackidx - 1].tagname;
+      }
+
+      if (put_line(fd, "enew | setl bt=help") == FAIL
+          || fprintf(fd, "help %s", curtag) < 0 || put_eol(fd) == FAIL) {
+        return FAIL;
+      }
+    } else if (wp->w_buffer->b_ffname != NULL
+               && (!bt_nofile(wp->w_buffer) || wp->w_buffer->terminal)) {
+      // Load the file.
+
       // Editing a file in this buffer: use ":edit file".
       // This may have side effects! (e.g., compressed or network file).
       //
diff --git a/src/nvim/testdir/test_mksession.vim b/src/nvim/testdir/test_mksession.vim
index 057895047d..a87691abf9 100644
--- a/src/nvim/testdir/test_mksession.vim
+++ b/src/nvim/testdir/test_mksession.vim
@@ -696,6 +696,36 @@ func Test_mksession_foldopt()
   set sessionoptions&
 endfunc
 
+" Test for mksession with "help" but not "options" in 'sessionoptions'
+func Test_mksession_help_noopt()
+  set sessionoptions-=options
+  set sessionoptions+=help
+  help
+  let fname = expand('%')
+  mksession! Xtest_mks.out
+  bwipe
+
+  source Xtest_mks.out
+  call assert_equal('help', &buftype)
+  call assert_equal('help', &filetype)
+  call assert_equal(fname, expand('%'))
+  call assert_false(&modifiable)
+  call assert_true(&readonly)
+
+  helpclose
+  help index
+  let fname = expand('%')
+  mksession! Xtest_mks.out
+  bwipe
+
+  source Xtest_mks.out
+  call assert_equal('help', &buftype)
+  call assert_equal(fname, expand('%'))
+
+  call delete('Xtest_mks.out')
+  set sessionoptions&
+endfunc
+
 " Test for mksession with window position
 func Test_mksession_winpos()
   if !has('gui_running')