vim-patch:9.0.1516: cannot use special keys in <Cmd> mapping

Problem:    Cannot use special keys in <Cmd> mapping.
Solution:   Do allow for special keys in <Cmd> and <ScriptCmd> mappings.
            (closes vim/vim#12326)

3ab3a86481

src/nvim/getchar.c

@@ -554,6 +554,21 @@ void AppendToRedobuffLit(const char *str, int len)
   }
 }
 
+/// Append "s" to the redo buffer, leaving 3-byte special key codes unmodified
+/// and escaping other K_SPECIAL bytes.
+void AppendToRedobuffSpec(const char *s)
+{
+  while (*s != NUL) {
+    if ((uint8_t)(*s) == K_SPECIAL && s[1] != NUL && s[2] != NUL) {
+      // Insert special key literally.
+      add_buff(&redobuff, s, 3L);
+      s += 3;
+    } else {
+      add_char_buff(&redobuff, mb_cptr2char_adv(&s));
+    }
+  }
+}
+
 /// Append a character to the redo buffer.
 /// Translates special keys, NUL, K_SPECIAL and multibyte characters.
 void AppendCharToRedobuff(int c)
@@ -2927,11 +2942,6 @@ char *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
       }
       c1 = TO_SPECIAL(c1, c2);
     }
-    if (c1 == Ctrl_V) {
-      // CTRL-V is followed by octal, hex or other characters, reverses
-      // what AppendToRedobuffLit() does.
-      c1 = get_literal(true);
-    }
 
     if (got_int) {
       aborted = true;

src/nvim/ops.c

@@ -5858,7 +5858,7 @@ void do_pending_operator(cmdarg_T *cap, int old_col, bool gui_yank)
         if (repeat_cmdline == NULL) {
           ResetRedobuff();
         } else {
-          AppendToRedobuffLit(repeat_cmdline, -1);
+          AppendToRedobuffSpec(repeat_cmdline);
           AppendToRedobuff(NL_STR);
           XFREE_CLEAR(repeat_cmdline);
         }

test/old/testdir/test_mapping.vim

@@ -979,10 +979,6 @@ func Test_map_cmdkey()
   call assert_fails('call feedkeys("\<F3>", "xt")', 'E1136:')
   call assert_equal(0, x)
 
-  noremap <F3> <Cmd><F3>let x = 2<CR>
-  call assert_fails('call feedkeys("\<F3>", "xt")', 'E1137:')
-  call assert_equal(0, x)
-
   noremap <F3> <Cmd>let x = 3
   call assert_fails('call feedkeys("\<F3>", "xt!")', 'E1255:')
   call assert_equal(0, x)
@@ -1084,11 +1080,6 @@ func Test_map_cmdkey()
   unmap <F3>
   unmap! <F3>
   %bw!
-
-  " command line ending in "0" is handled without errors
-  onoremap ix <cmd>eval 0<cr>
-  call feedkeys('dix.', 'xt')
-  ounmap ix
 endfunc
 
 " text object enters visual mode
@@ -1475,6 +1466,24 @@ func Test_map_cmdkey_redo()
   call delete('Xcmdtext')
   delfunc SelectDash
   ounmap i-
+
+  new
+  call setline(1, 'aaa bbb ccc ddd')
+
+  " command can contain special keys
+  onoremap ix <Cmd>let g:foo ..= '…'<Bar>normal! <C-Right><CR>
+  let g:foo = ''
+  call feedkeys('0dix.', 'xt')
+  call assert_equal('……', g:foo)
+  call assert_equal('ccc ddd', getline(1))
+  unlet g:foo
+
+  " command line ending in "0" is handled without errors
+  onoremap ix <Cmd>eval 0<CR>
+  call feedkeys('dix.', 'xt')
+
+  ounmap ix
+  bwipe!
 endfunc
 
 " Test for using <script> with a map to remap characters in rhs