vim-patch:8.2.4655: cmdline completion popup menu positioned wrong (#21894)

Problem:    Command line completion popup menu positioned wrong when using a
            terminal window.
Solution:   Position the popup menu differently when editing the command line.
            (Yegappan Lakshmanan, closes vim/vim#10050, closes vim/vim#10035)

https://github.com/vim/vim/commit/1104a6d0c2004d39e9b6cb8f804d12b628a69869

The test in the patch looks a bit hard to understand.
Add a Lua test that is more straightforward.

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

2 files changed, 43 insertions, 10 deletions

diff --git a/src/nvim/popupmenu.c b/src/nvim/popupmenu.c
index 14ee71d50a..b97a25dd0b 100644
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -218,11 +218,16 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
       // pum above "pum_win_row"
       pum_above = true;
 
-      // Leave two lines of context if possible
-      if (curwin->w_wrow - curwin->w_cline_row >= 2) {
-        context_lines = 2;
+      if (State == MODE_CMDLINE) {
+        // for cmdline pum, no need for context lines
+        context_lines = 0;
       } else {
-        context_lines = curwin->w_wrow - curwin->w_cline_row;
+        // Leave two lines of context if possible
+        if (curwin->w_wrow - curwin->w_cline_row >= 2) {
+          context_lines = 2;
+        } else {
+          context_lines = curwin->w_wrow - curwin->w_cline_row;
+        }
       }
 
       if (pum_win_row >= size + context_lines) {
@@ -241,13 +246,17 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
       // pum below "pum_win_row"
       pum_above = false;
 
-      // Leave two lines of context if possible
-      validate_cheight();
-      if (curwin->w_cline_row + curwin->w_cline_height - curwin->w_wrow >= 3) {
-        context_lines = 3;
+      if (State == MODE_CMDLINE) {
+        // for cmdline pum, no need for context lines
+        context_lines = 0;
       } else {
-        context_lines = curwin->w_cline_row
-                        + curwin->w_cline_height - curwin->w_wrow;
+        // Leave two lines of context if possible
+        validate_cheight();
+        if (curwin->w_cline_row + curwin->w_cline_height - curwin->w_wrow >= 3) {
+          context_lines = 3;
+        } else {
+          context_lines = curwin->w_cline_row + curwin->w_cline_height - curwin->w_wrow;
+        }
       }
 
       pum_row = pum_win_row + context_lines;
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index 980b8c5b38..150f4e01ef 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -2610,6 +2610,30 @@ func Test_wildmenumode_with_pum()
   cunmap <F2>
 endfunc
 
+" Test for opening the cmdline completion popup menu from the terminal window.
+" The popup menu should be positioned correctly over the status line of the
+" bottom-most window.
+func Test_wildmenu_pum_from_terminal()
+  CheckRunVimInTerminal
+  let python = PythonProg()
+  call CheckPython(python)
+
+  %bw!
+  let cmds = ['set wildmenu wildoptions=pum']
+  let pcmd = python .. ' -c "import sys; sys.stdout.write(sys.stdin.read())"'
+  call add(cmds, "call term_start('" .. pcmd .. "')")
+  call writefile(cmds, 'Xtest')
+  let buf = RunVimInTerminal('-S Xtest', #{rows: 10})
+  call term_sendkeys(buf, "\r\r\r")
+  call term_wait(buf)
+  call term_sendkeys(buf, "\<C-W>:sign \<Tab>")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, 'Test_wildmenu_pum_term_01', {})
+  call term_wait(buf)
+  call StopVimInTerminal(buf)
+  call delete('Xtest')
+endfunc
+
 func Test_wildmenu_pum_clear_entries()
   CheckRunVimInTerminal