vim-patch:8.2.{4692,4691,4690}: fix Insert mode <LeftDrag> mapping bug (#17999)

vim-patch:8.2.4692: no test for what 8.2.4691 fixes

Problem:    No test for what 8.2.4691 fixes.
Solution:   Add a test.  Use a more generic sotlution. (closes vim/vim#10090)
0f68e6c07a

Test cannot be used because it must use test_setmouse(). Use a Lua test.

Reverted patches:

vim-patch:8.2.4691: solution for <Cmd> in a mapping causes trouble

Problem:    Solution for <Cmd> in a mapping causes trouble.
Solution:   Use another solution: put back CTRL-O after reading the <Cmd>
            sequence.
ca9d8d2cb9

vim-patch:8.2.4689: using <Cmd> in a mapping does not work for mouse keys

Problem:    Using <Cmd> in a mapping does not work for mouse keys in Insert
            mode. (Sergey Vlasov)
Solution:   When reading the <Cmd> argument do not use the stuff buffer.
            (closes vim/vim#10080)
d0fb2d8041

src/nvim/getchar.c

@@ -1253,7 +1253,14 @@ static int old_mod_mask;    // mod_mask for ungotten character
 static int old_mouse_grid;  // mouse_grid related to old_char
 static int old_mouse_row;   // mouse_row related to old_char
 static int old_mouse_col;   // mouse_col related to old_char
+static int old_KeyStuffed;  // whether old_char was stuffed
 
+static bool can_get_old_char(void)
+{
+    // If the old character was not stuffed and characters have been added to
+    // the stuff buffer, need to first get the stuffed characters instead.
+    return old_char != -1 && (old_KeyStuffed || stuff_empty());
+}
 
 /*
  * Save all three kinds of typeahead, so that the user must type at a prompt.
@@ -1454,7 +1461,7 @@ int vgetc(void)
    * If a character was put back with vungetc, it was already processed.
    * Return it directly.
    */
-  if (old_char != -1) {
+  if (can_get_old_char()) {
     c = old_char;
     old_char = -1;
     mod_mask = old_mod_mask;
@@ -1660,7 +1667,7 @@ int plain_vgetc(void)
  */
 int vpeekc(void)
 {
-  if (old_char != -1) {
+  if (can_get_old_char()) {
     return old_char;
   }
   return vgetorpeek(false);
@@ -2052,7 +2059,9 @@ static int handle_mapping(int *keylenp, bool *timedout, int *mapdepth)
   return map_result_nomatch;
 }
 
-// unget one character (can only be done once!)
+/// unget one character (can only be done once!)
+/// If the character was stuffed, vgetc() will get it next time it was called.
+/// Otherwise vgetc() will only get it when the stuff buffer is empty.
 void vungetc(int c)
 {
   old_char = c;
@@ -2060,6 +2069,7 @@ void vungetc(int c)
   old_mouse_grid = mouse_grid;
   old_mouse_row = mouse_row;
   old_mouse_col = mouse_col;
+  old_KeyStuffed = KeyStuffed;
 }
 
 /// Gets a byte:

src/nvim/normal.c

@@ -1517,9 +1517,12 @@ bool do_mouse(oparg_T *oap, int c, int dir, long count, bool fixindent)
   for (;;) {
     which_button = get_mouse_button(KEY2TERMCAP1(c), &is_click, &is_drag);
     if (is_drag) {
-      /* If the next character is the same mouse event then use that
-       * one. Speeds up dragging the status line. */
-      if (vpeekc() != NUL) {
+      // If the next character is the same mouse event then use that
+      // one. Speeds up dragging the status line.
+      // Note: Since characters added to the stuff buffer in the code
+      // below need to come before the next character, do not do this
+      // when the current character was stuffed.
+      if (!KeyStuffed && vpeekc() != NUL) {
         int nc;
         int save_mouse_grid = mouse_grid;
         int save_mouse_row = mouse_row;

src/nvim/testdir/test_mapping.vim

@@ -676,4 +676,38 @@ func Test_plug_remap()
   %bw!
 endfunc
 
+" Test for mapping <LeftDrag> in Insert mode
+func Test_mouse_drag_insert_map()
+  CheckFunction test_setmouse
+  set mouse=a
+  func ClickExpr()
+    call test_setmouse(1, 1)
+    return "\<LeftMouse>"
+  endfunc
+  func DragExpr()
+    call test_setmouse(1, 2)
+    return "\<LeftDrag>"
+  endfunc
+  inoremap <expr> <F2> ClickExpr()
+  imap <expr> <F3> DragExpr()
+
+  inoremap <LeftDrag> <LeftDrag><Cmd>let g:dragged = 1<CR>
+  exe "normal i\<F2>\<F3>"
+  call assert_equal(1, g:dragged)
+  call assert_equal('v', mode())
+  exe "normal! \<C-\>\<C-N>"
+  unlet g:dragged
+
+  inoremap <LeftDrag> <LeftDrag><C-\><C-N>
+  exe "normal i\<F2>\<F3>"
+  call assert_equal('n', mode())
+
+  iunmap <LeftDrag>
+  iunmap <F2>
+  iunmap <F3>
+  delfunc ClickExpr
+  delfunc DragExpr
+  set mouse&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/functional/legacy/mapping_spec.lua

@@ -3,6 +3,8 @@
 local helpers = require('test.functional.helpers')(after_each)
 local clear, feed, insert = helpers.clear, helpers.feed, helpers.insert
 local feed_command, expect, poke_eventloop = helpers.feed_command, helpers.expect, helpers.poke_eventloop
+local command, eq, eval, meths = helpers.command, helpers.eq, helpers.eval, helpers.meths
+local sleep = helpers.sleep
 
 describe('mapping', function()
   before_each(clear)
@@ -126,4 +128,28 @@ describe('mapping', function()
       new line here
       ]])
   end)
+
+  it('<LeftDrag> mapping in Insert mode works correctly vim-patch:8.2.4692', function()
+    command('set mouse=a')
+
+    command([[inoremap <LeftDrag> <LeftDrag><Cmd>let g:dragged = 1<CR>]])
+    feed('i')
+    sleep(10)
+    meths.input_mouse('left', 'press', '', 0, 0, 0)
+    sleep(10)
+    meths.input_mouse('left', 'drag', '', 0, 0, 1)
+    sleep(10)
+    eq(1, eval('g:dragged'))
+    eq('v', eval('mode()'))
+    feed([[<C-\><C-N>]])
+
+    command([[inoremap <LeftDrag> <LeftDrag><C-\><C-N>]])
+    feed('i')
+    sleep(10)
+    meths.input_mouse('left', 'press', '', 0, 0, 0)
+    sleep(10)
+    meths.input_mouse('left', 'drag', '', 0, 0, 1)
+    sleep(10)
+    eq('n', eval('mode()'))
+  end)
 end)