vim-patch:8.0.1570: can't use :popup for a menu in the terminal

Problem:    Can't use :popup for a menu in the terminal. (Wei Zhang)
Solution:   Make :popup work in the terminal.  Also fix that entries were
            included that don't work in the current state.
29a2c08d79

src/nvim/ex_cmds.lua

@@ -1991,7 +1991,7 @@ module.cmds = {
     command='popup',
     flags=bit.bor(NEEDARG, EXTRA, BANG, TRLBAR, NOTRLCOM, CMDWIN),
     addr_type='ADDR_NONE',
-    func='ex_ni',
+    func='ex_popup',
   },
   {
     command='ppop',

src/nvim/ex_docmd.c

@@ -62,6 +62,7 @@
 #include "nvim/os/time.h"
 #include "nvim/os_unix.h"
 #include "nvim/path.h"
+#include "nvim/popupmnu.h"
 #include "nvim/quickfix.h"
 #include "nvim/regexp.h"
 #include "nvim/screen.h"
@@ -7985,6 +7986,11 @@ static void ex_nogui(exarg_T *eap)
   eap->errmsg = N_("E25: Nvim does not have a built-in GUI");
 }
 
+static void ex_popup(exarg_T *eap)
+{
+  pum_make_popup(eap->arg, eap->forceit);
+}
+
 static void ex_swapname(exarg_T *eap)
 {
   if (curbuf->b_ml.ml_mfp == NULL || curbuf->b_ml.ml_mfp->mf_fname == NULL) {

src/nvim/menu.c

@@ -1382,6 +1382,16 @@ static int get_menu_mode(void)
   return MENU_INDEX_INVALID;
 }
 
+int get_menu_mode_flag(void)
+{
+  int mode = get_menu_mode();
+
+  if (mode == MENU_INDEX_INVALID) {
+    return 0;
+  }
+  return 1 << mode;
+}
+
 /// Display the Special "PopUp" menu as a pop-up at the current mouse
 /// position.  The "PopUpn" menu is for Normal mode, "PopUpi" for Insert mode,
 /// etc.
@@ -1545,6 +1555,52 @@ void ex_emenu(exarg_T *eap)
   execute_menu(eap, menu);
 }
 
+/// Given a menu descriptor, e.g. "File.New", find it in the menu hierarchy.
+vimmenu_T *menu_find(const char *path_name)
+{
+  vimmenu_T *menu = *get_root_menu(path_name);
+  char *saved_name = xstrdup(path_name);
+  char *name = saved_name;
+  while (*name) {
+    // find the end of one dot-separated name and put a NUL at the dot
+    char *p = menu_name_skip(name);
+
+    while (menu != NULL) {
+      if (menu_name_equal(name, menu)) {
+        if (menu->children == NULL) {
+          // found a menu item instead of a sub-menu
+          if (*p == NUL) {
+            emsg(_("E336: Menu path must lead to a sub-menu"));
+          } else {
+            emsg(_(e_notsubmenu));
+          }
+          menu = NULL;
+          goto theend;
+        }
+        if (*p == NUL) {  // found a full match
+          goto theend;
+        }
+        break;
+      }
+      menu = menu->next;
+    }
+    if (menu == NULL) {  // didn't find it
+      break;
+    }
+
+    // Found a match, search the sub-menu.
+    menu = menu->children;
+    name = p;
+  }
+
+  if (menu == NULL) {
+    emsg(_("E337: Menu not found - check menu names"));
+  }
+theend:
+  xfree(saved_name);
+  return menu;
+}
+
 /*
  * Translation of menu names.  Just a simple lookup table.
  */

src/nvim/popupmnu.c

@@ -1000,9 +1000,12 @@ void pum_show_popupmenu(vimmenu_T *menu)
 {
   pum_undisplay(true);
   pum_size = 0;
+  int mode = get_menu_mode_flag();
 
   for (vimmenu_T *mp = menu->children; mp != NULL; mp = mp->next) {
-    pum_size++;
+    if (menu_is_separator(mp->dname) || (mp->modes & mp->enabled & mode)) {
+      pum_size++;
+    }
   }
 
   int idx = 0;
@@ -1011,7 +1014,7 @@ void pum_show_popupmenu(vimmenu_T *menu)
   for (vimmenu_T *mp = menu->children; mp != NULL; mp = mp->next) {
     if (menu_is_separator(mp->dname)) {
       array[idx++].pum_text = (char_u *)"";
-    } else {
+    } else if (mp->modes & mp->enabled & mode) {
       array[idx++].pum_text = (char_u *)mp->dname;
     }
   }
@@ -1079,3 +1082,18 @@ void pum_show_popupmenu(vimmenu_T *menu)
   xfree(array);
   pum_undisplay(true);
 }
+
+void pum_make_popup(const char *path_name, int use_mouse_pos)
+{
+  if (!use_mouse_pos) {
+    // Hack: set mouse position at the cursor so that the menu pops up
+    // around there.
+    mouse_row = curwin->w_winrow + curwin->w_wrow;
+    mouse_col = curwin->w_wincol + curwin->w_wcol;
+  }
+
+  vimmenu_T *menu = menu_find(path_name);
+  if (menu != NULL) {
+    pum_show_popupmenu(menu);
+  }
+}