vim-patch:9.1.0507: hard to detect cursor movement in the command line

Problem:  hard to detect cursor movement in the command line
Solution: Add the CursorMovedC autocommand
          (Shougo Matsushita)

closes: vim/vim#15040

https://github.com/vim/vim/commit/d09521476f41dd8dbddb25b7acd0b299f9bf94d3

Co-authored-by: Shougo Matsushita <Shougo.Matsu@gmail.com>

5 files changed, 70 insertions, 19 deletions

diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index ca816851dd..d0768c6f8c 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -522,6 +522,13 @@ CursorMoved			After the cursor was moved in Normal or Visual
 				Careful: This is triggered very often, don't
 				do anything that the user does not expect or
 				that is slow.
+							*CursorMovedC*
+CursorMovedC			After the cursor was moved in the command
+				line. Be careful not to mess up the
+				command line, it may cause Vim to lock up.
+				<afile> is set to a single character,
+				indicating the type of command-line.
+				|cmdwin-char|
 							*CursorMovedI*
 CursorMovedI			After the cursor was moved in Insert mode.
 				Not triggered when the popup menu is visible.
diff --git a/src/nvim/auevents.lua b/src/nvim/auevents.lua
index 3946ffd960..e61f1a8ce2 100644
--- a/src/nvim/auevents.lua
+++ b/src/nvim/auevents.lua
@@ -36,6 +36,7 @@ return {
     'CursorHold', -- cursor in same position for a while
     'CursorHoldI', -- idem, in Insert mode
     'CursorMoved', -- cursor was moved
+    'CursorMovedC', -- cursor was moved in Cmdline mode
     'CursorMovedI', -- cursor was moved in Insert mode
     'DiagnosticChanged', -- diagnostics in a buffer were modified
     'DiffUpdated', -- diffs have been updated
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index c32d33080e..9716a2869a 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -1700,19 +1700,33 @@ bool apply_autocmds_group(event_T event, char *fname, char *fname_io, bool force
   } else {
     sfname = xstrdup(fname);
     // Don't try expanding the following events.
-    if (event == EVENT_CMDLINECHANGED || event == EVENT_CMDLINEENTER
-        || event == EVENT_CMDLINELEAVE || event == EVENT_CMDUNDEFINED
-        || event == EVENT_CMDWINENTER || event == EVENT_CMDWINLEAVE
-        || event == EVENT_COLORSCHEME || event == EVENT_COLORSCHEMEPRE
-        || event == EVENT_DIRCHANGED || event == EVENT_DIRCHANGEDPRE
-        || event == EVENT_FILETYPE || event == EVENT_FUNCUNDEFINED
-        || event == EVENT_MENUPOPUP || event == EVENT_MODECHANGED
-        || event == EVENT_OPTIONSET || event == EVENT_QUICKFIXCMDPOST
-        || event == EVENT_QUICKFIXCMDPRE || event == EVENT_REMOTEREPLY
-        || event == EVENT_SIGNAL || event == EVENT_SPELLFILEMISSING
-        || event == EVENT_SYNTAX || event == EVENT_TABCLOSED
-        || event == EVENT_USER || event == EVENT_WINCLOSED
-        || event == EVENT_WINRESIZED || event == EVENT_WINSCROLLED) {
+    if (event == EVENT_CMDLINECHANGED
+        || event == EVENT_CMDLINEENTER
+        || event == EVENT_CMDLINELEAVE
+        || event == EVENT_CMDUNDEFINED
+        || event == EVENT_CURSORMOVEDC
+        || event == EVENT_CMDWINENTER
+        || event == EVENT_CMDWINLEAVE
+        || event == EVENT_COLORSCHEME
+        || event == EVENT_COLORSCHEMEPRE
+        || event == EVENT_DIRCHANGED
+        || event == EVENT_DIRCHANGEDPRE
+        || event == EVENT_FILETYPE
+        || event == EVENT_FUNCUNDEFINED
+        || event == EVENT_MENUPOPUP
+        || event == EVENT_MODECHANGED
+        || event == EVENT_OPTIONSET
+        || event == EVENT_QUICKFIXCMDPOST
+        || event == EVENT_QUICKFIXCMDPRE
+        || event == EVENT_REMOTEREPLY
+        || event == EVENT_SIGNAL
+        || event == EVENT_SPELLFILEMISSING
+        || event == EVENT_SYNTAX
+        || event == EVENT_TABCLOSED
+        || event == EVENT_USER
+        || event == EVENT_WINCLOSED
+        || event == EVENT_WINRESIZED
+        || event == EVENT_WINSCROLLED) {
       fname = xstrdup(fname);
       autocmd_fname_full = true;  // don't expand it later
     } else {
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 588f0aea13..8e0378dd68 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -133,7 +133,8 @@ typedef struct {
   int did_wild_list;                    // did wild_list() recently
   int wim_index;                        // index in wim_flags[]
   int save_msg_scroll;
-  int save_State;                 // remember State when called
+  int save_State;                       // remember State when called
+  int save_cmdspos;
   char *save_p_icm;
   int some_key_typed;                   // one of the keys was typed
   // mouse drag and release events are ignored, unless they are
@@ -223,6 +224,12 @@ static int cmdpreview_ns = 0;
 static const char e_active_window_or_buffer_changed_or_deleted[]
   = N_("E199: Active window or buffer changed or deleted");
 
+static void trigger_cmd_autocmd(int typechar, event_T evt)
+{
+  char typestr[2] = { (char)typechar, NUL };
+  apply_autocmds(evt, typestr, typestr, false, curbuf);
+}
+
 static void save_viewstate(win_T *wp, viewstate_T *vs)
   FUNC_ATTR_NONNULL_ALL
 {
@@ -684,6 +691,7 @@ static uint8_t *command_line_enter(int firstc, int count, int indent, bool clear
     .indent = indent,
     .save_msg_scroll = msg_scroll,
     .save_State = State,
+    .save_cmdspos = ccline.cmdspos,
     .ignore_drag_release = true,
   };
   CommandLineState *s = &state;
@@ -2175,6 +2183,11 @@ static int command_line_handle_key(CommandLineState *s)
 
 static int command_line_not_changed(CommandLineState *s)
 {
+  // Trigger CursorMovedC autocommands.
+  if (ccline.cmdspos != s->save_cmdspos) {
+    trigger_cmd_autocmd(get_cmdline_type(), EVENT_CURSORMOVEDC);
+  }
+
   // Incremental searches for "/" and "?":
   // Enter command_line_not_changed() when a character has been read but the
   // command line did not change. Then we only search and redraw if something
@@ -4177,6 +4190,10 @@ static int set_cmdline_pos(int pos)
   } else {
     new_cmdpos = pos;
   }
+
+  // Trigger CursorMovedC autocommands.
+  trigger_cmd_autocmd(get_cmdline_type(), EVENT_CURSORMOVEDC);
+
   return 0;
 }
 
@@ -4303,7 +4320,6 @@ static int open_cmdwin(void)
   win_T *old_curwin = curwin;
   int i;
   garray_T winsizes;
-  char typestr[2];
   int save_restart_edit = restart_edit;
   int save_State = State;
   bool save_exmode = exmode_active;
@@ -4446,9 +4462,7 @@ static int open_cmdwin(void)
   cmdwin_result = 0;
 
   // Trigger CmdwinEnter autocommands.
-  typestr[0] = (char)cmdwin_type;
-  typestr[1] = NUL;
-  apply_autocmds(EVENT_CMDWINENTER, typestr, typestr, false, curbuf);
+  trigger_cmd_autocmd(cmdwin_type, EVENT_CMDWINENTER);
   if (restart_edit != 0) {  // autocmd with ":startinsert"
     stuffcharReadbuff(K_NOP);
   }
@@ -4466,7 +4480,7 @@ static int open_cmdwin(void)
   const bool save_KeyTyped = KeyTyped;
 
   // Trigger CmdwinLeave autocommands.
-  apply_autocmds(EVENT_CMDWINLEAVE, typestr, typestr, false, curbuf);
+  trigger_cmd_autocmd(cmdwin_type, EVENT_CMDWINLEAVE);
 
   // Restore KeyTyped in case it is modified by autocommands
   KeyTyped = save_KeyTyped;
diff --git a/test/old/testdir/test_autocmd.vim b/test/old/testdir/test_autocmd.vim
index cdcd68f3d6..9132e0fdce 100644
--- a/test/old/testdir/test_autocmd.vim
+++ b/test/old/testdir/test_autocmd.vim
@@ -2010,6 +2010,21 @@ func Test_Cmdline()
   au! CmdlineEnter
   au! CmdlineLeave
   let &shellslash = save_shellslash
+
+  au! CursorMovedC : let g:pos = getcmdpos()
+  let g:pos = 0
+  call feedkeys(":hello\<Left>\<ESC>", 'xt')
+  call assert_equal(5, g:pos)
+  call feedkeys(":12345678\<C-R>=setcmdpos(3)\<CR>\<ESC>", 'xt')
+  call assert_equal(3, g:pos)
+  au! CursorMovedC
+
+  " CursorMovedC changes the cursor position.
+  au! CursorMovedC : let g:pos = getcmdpos() | call setcmdpos(getcmdpos()-1)
+  let g:pos = 0
+  call feedkeys(":hello\<Left>\<ESC>", 'xt')
+  call assert_equal(5, g:pos)
+  au! CursorMovedC
 endfunc
 
 " Test for BufWritePre autocommand that deletes or unloads the buffer.