vim-patch:8.2.1413: previous tab page not usable from an Ex command

Problem:    Previous tab page not usable from an Ex command.
Solution:   Add the "#" argument for :tabnext et al. (Yegappan Lakshmanan,
            closes vim/vim#6677)
https://github.com/vim/vim/commit/94f4ffa7704921a3634e56b878e6dc362bc3d508

Do not rename old_curtab to prev_tp in win_new_tabpage, this can be confused
with the previous tabpage (`:tabprevious`).

Cherry-pick ex_errmsg from v8.2.1280.
https://github.com/vim/vim/commit/8930caaa1a283092aca81fdbc3fcf15c7eadb197

1 files changed, 19 insertions, 1 deletions

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 6bd465e6ee..09cf6601ee 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2036,6 +2036,18 @@ doend:
   return ea.nextcmd;
 }
 
+static char ex_error_buf[MSG_BUF_LEN];
+
+/// @return an error message with argument included.
+/// Uses a static buffer, only the last error will be kept.
+/// "msg" will be translated, caller should use N_().
+char *ex_errmsg(const char *const msg, const char_u *const arg)
+  FUNC_ATTR_NONNULL_ALL
+{
+  vim_snprintf(ex_error_buf, MSG_BUF_LEN, _(msg), arg);
+  return ex_error_buf;
+}
+
 // Parse and skip over command modifiers:
 // - update eap->cmd
 // - store flags in "cmdmod".
@@ -4861,7 +4873,13 @@ static int get_tabpage_arg(exarg_T *eap)
       if (STRCMP(p, "$") == 0) {
         tab_number = LAST_TAB_NR;
       } else if (STRCMP(p, "#") == 0) {
-        tab_number = tabpage_index(lastused_tabpage);
+        if (valid_tabpage(lastused_tabpage)) {
+          tab_number = tabpage_index(lastused_tabpage);
+        } else {
+          eap->errmsg = ex_errmsg(e_invargval, eap->arg);
+          tab_number = 0;
+          goto theend;
+        }
       } else if (p == p_save || *p_save == '-' || *p != NUL
                  || tab_number > LAST_TAB_NR) {
         // No numbers as argument.