vim-patch:8.2.3555: ModeChanged is not triggered on every mode change

Problem:    ModeChanged is not triggered on every mode change.
Solution:   Also trigger on minor mode changes. (Maguns Gross, closes vim/vim#8999)
25def2c8b8

runtime/doc/autocmd.txt

@@ -721,18 +721,23 @@ MenuPopup			Just before showing the popup menu (under the
 							*ModeChanged*
 ModeChanged			After changing the mode. The pattern is
 				matched against `'old_mode:new_mode'`, for
-				example match against `i:*` to simulate
-				|InsertLeave|.
+				example match against `*:c` to simulate
+				|CmdlineEnter|.
 				The following values of |v:event| are set:
 					old_mode The mode before it changed.
 					new_mode The new mode as also returned
-						by |mode()|.
+						by |mode()| called with a
+						non-zero argument.
 				When ModeChanged is triggered, old_mode will
 				have the value of new_mode when the event was
 				last triggered.
+				This will be triggered on every minor mode
+				change.
 				Usage example to use relative line numbers
 				when entering visual mode: >
-					:autocmd ModeChanged *:v set rnu
+		:au ModeChanged [vV\x16]*:* let &l:rnu = mode() =~# '^[vV\x16]'
+		:au ModeChanged *:[vV\x16]* let &l:rnu = mode() =~# '^[vV\x16]'
+		:au WinEnter,WinLeave * let &l:rnu = mode() =~# '^[vV\x16]'
 <							*OptionSet*
 OptionSet			After setting an option (except during
 				|startup|).  The |autocmd-pattern| is matched

src/nvim/autocmd.c

@@ -925,6 +925,13 @@ static int do_autocmd_event(event_T event, char_u *pat, bool once, int nested, c
             return FAIL;
           }
         }
+
+        // need to initialize last_mode for the first ModeChanged autocmd
+        if (event == EVENT_MODECHANGED && !has_event(EVENT_MODECHANGED)) {
+          xfree(last_mode);
+          last_mode = get_mode();
+        }
+
         ap->cmds = NULL;
         *prev_ap = ap;
         last_autopat[(int)event] = ap;

src/nvim/edit.c

@@ -2049,6 +2049,8 @@ static void ins_ctrl_x(void)
     // CTRL-V look like CTRL-N
     ctrl_x_mode = CTRL_X_CMDLINE_CTRL_X;
   }
+
+  trigger_modechanged();
 }
 
 // Whether other than default completion has been selected.
@@ -2661,6 +2663,7 @@ void set_completion(colnr_T startcol, list_T *list)
     show_pum(save_w_wrow, save_w_leftcol);
   }
 
+  trigger_modechanged();
   ui_flush();
 }
 
@@ -3839,6 +3842,8 @@ static bool ins_compl_prep(int c)
     ins_apply_autocmds(EVENT_COMPLETEDONE);
   }
 
+  trigger_modechanged();
+
   /* reset continue_* if we left expansion-mode, if we stay they'll be
    * (re)set properly in ins_complete() */
   if (!vim_is_ctrl_x_key(c)) {
@@ -4587,6 +4592,8 @@ static int ins_compl_get_exp(pos_T *ini)
       compl_curr_match = compl_old_match;
     }
   }
+  trigger_modechanged();
+
   return i;
 }
 

src/nvim/misc1.c

@@ -1067,12 +1067,13 @@ void trigger_modechanged(void)
     return;
   }
 
-  dict_T *v_event = get_vim_var_dict(VV_EVENT);
-
   char *mode = get_mode();
-  if (last_mode == NULL) {
-    last_mode = (char *)vim_strsave((char_u *)"n");
+  if (STRCMP(mode, last_mode) == 0) {
+    xfree(mode);
+    return;
   }
+
+  dict_T *v_event = get_vim_var_dict(VV_EVENT);
   tv_dict_add_str(v_event, S_LEN("new_mode"), mode);
   tv_dict_add_str(v_event, S_LEN("old_mode"), last_mode);
 

src/nvim/normal.c

@@ -487,6 +487,7 @@ static void normal_prepare(NormalState *s)
   if (finish_op != c) {
     ui_cursor_shape();  // may show different cursor shape
   }
+  trigger_modechanged();
 
   // When not finishing an operator and no register name typed, reset the count.
   if (!finish_op && !s->oa.regname) {
@@ -928,6 +929,7 @@ normal_end:
   // Reset finish_op, in case it was set
   s->c = finish_op;
   finish_op = false;
+  trigger_modechanged();
   // Redraw the cursor with another shape, if we were in Operator-pending
   // mode or did a replace command.
   if (s->c || s->ca.cmdchar == 'r') {
@@ -965,6 +967,7 @@ normal_end:
       && s->oa.regname == 0) {
     if (restart_VIsual_select == 1) {
       VIsual_select = true;
+      trigger_modechanged();
       showmode();
       restart_VIsual_select = 0;
     }
@@ -3050,7 +3053,6 @@ static int get_mouse_class(char_u *p)
 void end_visual_mode(void)
 {
   VIsual_active = false;
-  trigger_modechanged();
   setmouse();
   mouse_dragging = 0;
 
@@ -3067,6 +3069,7 @@ void end_visual_mode(void)
   may_clear_cmdline();
 
   adjust_cursor_eol();
+  trigger_modechanged();
 }
 
 /*
@@ -4852,6 +4855,7 @@ static void nv_ctrlg(cmdarg_T *cap)
 {
   if (VIsual_active) {  // toggle Selection/Visual mode
     VIsual_select = !VIsual_select;
+    trigger_modechanged();
     showmode();
   } else if (!checkclearop(cap->oap)) {
     // print full name if count given or :cd used
@@ -4895,6 +4899,7 @@ static void nv_ctrlo(cmdarg_T *cap)
 {
   if (VIsual_active && VIsual_select) {
     VIsual_select = false;
+    trigger_modechanged();
     showmode();
     restart_VIsual_select = 2;          // restart Select mode later
   } else {

src/nvim/testdir/test_edit.vim

@@ -1646,12 +1646,8 @@ endfunc
 
 " Test for ModeChanged pattern
 func Test_mode_changes()
-  let g:count = 0
-  func! DoIt()
-    let g:count += 1
-  endfunc
   let g:index = 0
-  let g:mode_seq = ['n', 'i', 'n', 'v', 'V', 'n', 'V', 'v', 'n']
+  let g:mode_seq = ['n', 'i', 'n', 'v', 'V', 'i', 'ix', 'i', 'ic', 'i', 'n', 'no', 'n', 'V', 'v', 's', 'n']
   func! TestMode()
     call assert_equal(g:mode_seq[g:index], get(v:event, "old_mode"))
     call assert_equal(g:mode_seq[g:index + 1], get(v:event, "new_mode"))
@@ -1660,13 +1656,15 @@ func Test_mode_changes()
   endfunc
 
   au ModeChanged * :call TestMode()
-  au ModeChanged n:* :call DoIt()
-  call feedkeys("i\<esc>vV\<esc>", 'tnix')
-  call assert_equal(2, g:count)
+  let g:n_to_any = 0
+  au ModeChanged n:* let g:n_to_any += 1
+  call feedkeys("i\<esc>vVca\<CR>\<C-X>\<C-L>\<esc>ggdG", 'tnix')
 
-  au ModeChanged V:v :call DoIt()
-  call feedkeys("Vv\<esc>", 'tnix')
-  call assert_equal(4, g:count)
+  let g:V_to_v = 0
+  au ModeChanged V:v let g:V_to_v += 1
+  call feedkeys("Vv\<C-G>\<esc>", 'tnix')
+  call assert_equal(len(filter(g:mode_seq[1:], {idx, val -> val == 'n'})), g:n_to_any)
+  call assert_equal(1, g:V_to_v)
   call assert_equal(len(g:mode_seq) - 1, g:index)
 
   let g:n_to_i = 0
@@ -1695,12 +1693,32 @@ func Test_mode_changes()
   call assert_equal(2, g:i_to_any)
   call assert_equal(3, g:nori_to_any)
 
+  if has('terminal')
+    let g:mode_seq += ['c', 'n', 't', 'nt', 'c', 'nt', 'n']
+    call feedkeys(":term\<CR>\<C-W>N:bd!\<CR>", 'tnix')
+    call assert_equal(len(g:mode_seq) - 1, g:index)
+    call assert_equal(1, g:n_to_i)
+    call assert_equal(1, g:n_to_niI)
+    call assert_equal(1, g:niI_to_i)
+    call assert_equal(2, g:nany_to_i)
+    call assert_equal(1, g:i_to_n)
+    call assert_equal(2, g:i_to_any)
+    call assert_equal(5, g:nori_to_any)
+  endif
+
   au! ModeChanged
   delfunc TestMode
   unlet! g:mode_seq
   unlet! g:index
-  delfunc DoIt
-  unlet! g:count
+  unlet! g:n_to_any
+  unlet! g:V_to_v
+  unlet! g:n_to_i
+  unlet! g:n_to_niI
+  unlet! g:niI_to_i
+  unlet! g:nany_to_i
+  unlet! g:i_to_n
+  unlet! g:nori_to_any
+  unlet! g:i_to_any
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab