fix(cmdline): do not trigger completion at wrong time (#19920)

Cherry-picked from Vim patches 8.2.4339, 9.0.0238.

src/nvim/ex_getln.c

@@ -1277,8 +1277,11 @@ static int command_line_execute(VimState *state, int key)
   // <S-Tab> goes to last match, in a clumsy way
   if (s->c == K_S_TAB && KeyTyped) {
     if (nextwild(&s->xpc, WILD_EXPAND_KEEP, 0, s->firstc != '@') == OK) {
-      // Trigger the popup menu when wildoptions=pum
+      if (s->xpc.xp_numfiles > 1
-      showmatches(&s->xpc, p_wmnu && ((wim_flags[s->wim_index] & WIM_LIST) == 0));
+          && ((!s->did_wild_list && (wim_flags[s->wim_index] & WIM_LIST)) || p_wmnu)) {
+        // Trigger the popup menu when wildoptions=pum
+        showmatches(&s->xpc, p_wmnu && ((wim_flags[s->wim_index] & WIM_LIST) == 0));
+      }
       nextwild(&s->xpc, WILD_PREV, 0, s->firstc != '@');
       nextwild(&s->xpc, WILD_PREV, 0, s->firstc != '@');
       return command_line_changed(s);
@@ -1798,13 +1801,16 @@ static int command_line_handle_key(CommandLineState *s)
     return command_line_not_changed(s);
 
   case Ctrl_A:            // all matches
+    if (cmdline_pum_active()) {
+      // As Ctrl-A completes all the matches, close the popup
+      // menu (if present)
+      cmdline_pum_cleanup(&ccline);
+    }
     if (nextwild(&s->xpc, WILD_ALL, 0, s->firstc != '@') == FAIL) {
       break;
     }
-    if (cmdline_pum_active()) {
+    s->xpc.xp_context = EXPAND_NOTHING;
-      cmdline_pum_cleanup(&ccline);
+    s->did_wild_list = false;
-      s->xpc.xp_context = EXPAND_NOTHING;
-    }
     return command_line_changed(s);
 
   case Ctrl_L:

test/functional/ui/popupmenu_spec.lua

@@ -1990,6 +1990,22 @@ describe('builtin popupmenu', function()
       efine unplace^                   |
     ]])
 
+    -- Pressing <Left> after that should move the cursor
+    feed('<Left>')
+    screen:expect([[
+                                      |
+      {1:~                               }|
+      {1:~                               }|
+      {1:~                               }|
+      {1:~                               }|
+      {1:~                               }|
+      {1:~                               }|
+      {4:                                }|
+      :sign define jump list place und|
+      efine unplac^e                   |
+    ]])
+    feed('<End>')
+
     -- Pressing <C-D> when the popup menu is displayed should remove the popup
     -- menu
     feed('<C-U>sign <Tab><C-D>')

test/functional/ui/wildmode_spec.lua

@@ -461,20 +461,20 @@ end)
 describe('command line completion', function()
   local screen
   before_each(function()
+    clear()
     screen = Screen.new(40, 5)
     screen:set_default_attr_ids({
      [1] = {bold = true, foreground = Screen.colors.Blue1},
      [2] = {foreground = Screen.colors.Grey0, background = Screen.colors.Yellow},
      [3] = {bold = true, reverse = true},
     })
+    screen:attach()
   end)
   after_each(function()
     os.remove('Xtest-functional-viml-compl-dir')
   end)
 
   it('lists directories with empty PATH', function()
-    clear()
-    screen:attach()
     local tmp = funcs.tempname()
     command('e '.. tmp)
     command('cd %:h')
@@ -491,8 +491,6 @@ describe('command line completion', function()
   end)
 
   it('completes env var names #9681', function()
-    clear()
-    screen:attach()
     command('let $XTEST_1 = "foo" | let $XTEST_2 = "bar"')
     command('set wildmenu wildmode=full')
     feed(':!echo $XTEST_<tab>')
@@ -521,6 +519,58 @@ describe('command line completion', function()
       :!echo $XTEST_1AaあB^                    |
     ]])
   end)
+
+  it('does not leak memory with <S-Tab> with wildmenu and only one match #19874', function()
+    meths.set_option('wildmenu', true)
+    meths.set_option('wildmode', 'full')
+    meths.set_option('wildoptions', 'pum')
+
+    feed(':sign unpla<S-Tab>')
+    screen:expect([[
+                                              |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      :sign unplace^                           |
+    ]])
+
+    feed('<Space>buff<Tab>')
+    screen:expect([[
+                                              |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      :sign unplace buffer=^                   |
+    ]])
+  end)
+
+  it('does not show matches with <S-Tab> without wildmenu with wildmode=full', function()
+    meths.set_option('wildmenu', false)
+    meths.set_option('wildmode', 'full')
+
+    feed(':sign <S-Tab>')
+    screen:expect([[
+                                              |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      :sign unplace^                           |
+    ]])
+  end)
+
+  it('shows matches with <S-Tab> without wildmenu with wildmode=list', function()
+    meths.set_option('wildmenu', false)
+    meths.set_option('wildmode', 'list')
+
+    feed(':sign <S-Tab>')
+    screen:expect([[
+      {3:                                        }|
+      :sign define                            |
+      define    list      undefine            |
+      jump      place     unplace             |
+      :sign unplace^                           |
+    ]])
+  end)
 end)
 
 describe('ui/ext_wildmenu', function()