terminal: block redraw during c_CTRL-D

Unlike the normal wildmenu, the CTRL-D wild-list is not restored by
statusline redraw. (Semantics: ^D is controlled by 'wildoptions' option,
so it's in the "wild..." family.)

TODO: externalize the c_CTRL-D wild-list.

src/nvim/ex_getln.c

@@ -12,6 +12,7 @@
 #include <inttypes.h>
 
 #include "nvim/assert.h"
+#include "nvim/log.h"
 #include "nvim/vim.h"
 #include "nvim/ascii.h"
 #include "nvim/arabic.h"
@@ -472,11 +473,12 @@ static int command_line_execute(VimState *state, int key)
   }
 
   // free expanded names when finished walking through matches
-  if (s->xpc.xp_numfiles != -1
-      && !(s->c == p_wc && KeyTyped) && s->c != p_wcm
+  if (!(s->c == p_wc && KeyTyped) && s->c != p_wcm
       && s->c != Ctrl_N && s->c != Ctrl_P && s->c != Ctrl_A
       && s->c != Ctrl_L) {
+    if (s->xpc.xp_numfiles != -1) {
       (void)ExpandOne(&s->xpc, NULL, NULL, 0, WILD_FREE);
+    }
     s->did_wild_list = false;
     if (!p_wmnu || (s->c != K_UP && s->c != K_DOWN)) {
       s->xpc.xp_context = EXPAND_NOTHING;
@@ -1222,6 +1224,7 @@ static int command_line_handle_key(CommandLineState *s)
       break;                  // Use ^D as normal char instead
     }
 
+    wild_menu_showing = WM_LIST;
     redrawcmd();
     return 1;                 // don't do incremental search now
 

src/nvim/globals.h

@@ -931,8 +931,11 @@ EXTERN char_u langmap_mapchar[256];     /* mapping for language keys */
 EXTERN int save_p_ls INIT(= -1);        /* Save 'laststatus' setting */
 EXTERN int save_p_wmh INIT(= -1);       /* Save 'winminheight' setting */
 EXTERN int wild_menu_showing INIT(= 0);
-# define WM_SHOWN       1               /* wildmenu showing */
-# define WM_SCROLLED    2               /* wildmenu showing with scroll */
+enum {
+  WM_SHOWN = 1,     ///< wildmenu showing
+  WM_SCROLLED = 2,  ///< wildmenu showing with scroll
+  WM_LIST = 3,      ///< cmdline CTRL-D
+};
 
 
 EXTERN char breakat_flags[256];         /* which characters are in 'breakat' */

src/nvim/state.c

@@ -6,6 +6,7 @@
 #include "nvim/lib/kvec.h"
 
 #include "nvim/ascii.h"
+#include "nvim/log.h"
 #include "nvim/state.h"
 #include "nvim/vim.h"
 #include "nvim/main.h"

src/nvim/terminal.c

@@ -43,6 +43,7 @@
 
 #include <vterm.h>
 
+#include "nvim/log.h"
 #include "nvim/vim.h"
 #include "nvim/terminal.h"
 #include "nvim/message.h"
@@ -1010,7 +1011,10 @@ static void refresh_terminal(Terminal *term)
 // Calls refresh_terminal() on all invalidated_terminals.
 static void refresh_timer_cb(TimeWatcher *watcher, void *data)
 {
-  if (exiting) {  // Cannot redraw (requires event loop) during teardown/exit.
+  if (exiting  // Cannot redraw (requires event loop) during teardown/exit.
+      // WM_LIST (^D) is not redrawn, unlike the normal wildmenu. So we must
+      // skip redraws to keep it visible.
+      || wild_menu_showing == WM_LIST) {
     goto end;
   }
   Terminal *term;

test/functional/ui/wildmode_spec.lua

@@ -66,10 +66,10 @@ describe("'wildmenu'", function()
     else
       feed([[:terminal for i in $(seq 1 5000); do printf 'foo\nfoo\nfoo\n'; sleep 0.1; done<cr>]])
     end
-    screen:sleep(50)        -- Allow some output.
+
     feed([[<C-\><C-N>gg]])
     feed([[:sign <Tab>]])   -- Invoke wildmenu.
-    screen:sleep(50)        -- Allow some output.
+    screen:sleep(50)        -- Allow some terminal output.
     screen:expect([[
       foo                      |
       foo                      |
@@ -77,6 +77,28 @@ describe("'wildmenu'", function()
       define  jump  list  >    |
       :sign define^             |
     ]])
+
+    -- cmdline CTRL-D display should also be preserved.
+    feed([[<C-\><C-N>]])
+    feed([[:sign <C-D>]])   -- Invoke cmdline CTRL-D.
+    screen:sleep(50)        -- Allow some terminal output.
+    screen:expect([[
+      :sign                    |
+      define    place          |
+      jump      undefine       |
+      list      unplace        |
+      :sign ^                   |
+    ]])
+
+    -- Exiting cmdline should show the buffer.
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      ^foo                      |
+      foo                      |
+      foo                      |
+      foo                      |
+                               |
+    ]])
   end)
 
   it('ignores :redrawstatus called from a timer #7108', function()