vim-patch:8.2.1401: cannot jump to the last used tabpage

Problem:    Cannot jump to the last used tabpage.
Solution:   Add g<Tab> and tabpagnr('#'). (Yegappan Lakshmanan, closes vim/vim#6661,
            neovim #11626)
https://github.com/vim/vim/commit/62a232506d06f6d1b3b7271801c907d6294dfe84

Nvim implemented this feature before Vim, but Vim made some useful changes (e.g:
beeping on failure). Port the changes to closer match Vim (also makes porting
future patches easier).

Also note that because CHECK_CMDWIN was added to goto_tabpage_tp, there is no
need to do the extra work with tabpage_index and goto_tabpage inside
goto_tabpage_lastused to fix cmdwin issues any more (#11692).
Note that while goto_tabpage_tp doesn't check for textlock like goto_tabpage
does, it shouldn't matter as it is already checked for earlier.

Add tags for <C-Tab> to tabpage.txt, and refer to <C-Tab> over CTRL-Tab to be
consistent with other docs like the patch.
Remove mention of "previous tabpage" (it can be confused with the tabpage to the
left, e.g: `:tabprevious`).
Similarly, don't rename old_curtab to last_tab in enter_tabpage (it might be
confused with the right-most tabpage, e.g: `:tablast`).

Cherry-pick Test_tabpage change from v8.2.0634.
https://github.com/vim/vim/commit/92b83ccfda7a1d654ccaaf161a9c8a8e01fbcf76

1 files changed, 46 insertions, 0 deletions

diff --git a/src/nvim/testdir/test_tabpage.vim b/src/nvim/testdir/test_tabpage.vim
index 9869dc7590..b458f9a311 100644
--- a/src/nvim/testdir/test_tabpage.vim
+++ b/src/nvim/testdir/test_tabpage.vim
@@ -128,6 +128,8 @@ function Test_tabpage()
   1tabmove
   call assert_equal(2, tabpagenr())
 
+  call assert_fails('let t = tabpagenr("@")', 'E15:')
+  call assert_equal(0, tabpagewinnr(-1))
   call assert_fails("99tabmove", 'E16:')
   call assert_fails("+99tabmove", 'E16:')
   call assert_fails("-99tabmove", 'E16:')
@@ -683,4 +685,48 @@ func Test_tabline_tabmenu()
   %bw!
 endfunc
 
+" Test for jumping to last accessed tabpage
+func Test_lastused_tabpage()
+  tabonly!
+  call assert_equal(0, tabpagenr('#'))
+  call assert_beeps('call feedkeys("g\<Tab>", "xt")')
+  call assert_beeps('call feedkeys("\<C-Tab>", "xt")')
+  call assert_beeps('call feedkeys("\<C-W>g\<Tab>", "xt")')
+
+  " open four tab pages
+  tabnew
+  tabnew
+  tabnew
+
+  2tabnext
+
+  " Test for g<Tab>
+  call assert_equal(4, tabpagenr('#'))
+  call feedkeys("g\<Tab>", "xt")
+  call assert_equal(4, tabpagenr())
+  call assert_equal(2, tabpagenr('#'))
+
+  " Test for <C-Tab>
+  call feedkeys("\<C-Tab>", "xt")
+  call assert_equal(2, tabpagenr())
+  call assert_equal(4, tabpagenr('#'))
+
+  " Test for <C-W>g<Tab>
+  call feedkeys("\<C-W>g\<Tab>", "xt")
+  call assert_equal(4, tabpagenr())
+  call assert_equal(2, tabpagenr('#'))
+
+  " Try to jump to a closed tab page
+  tabclose 2
+  call assert_equal(0, tabpagenr('#'))
+  call feedkeys("g\<Tab>", "xt")
+  call assert_equal(3, tabpagenr())
+  call feedkeys("\<C-Tab>", "xt")
+  call assert_equal(3, tabpagenr())
+  call feedkeys("\<C-W>g\<Tab>", "xt")
+  call assert_equal(3, tabpagenr())
+
+  tabclose!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab