vim-patch:8.0.0878: no completion for :mapclear

Problem:    No completion for :mapclear.
Solution:   Add completion (Nobuhiro Takasaki et al. closes vim/vim#1943)
cae92dc3d5

runtime/doc/eval.txt

@@ -4099,6 +4099,7 @@ getcompletion({pat}, {type} [, {filtered}])		*getcompletion()*
 		highlight	highlight groups
 		history		:history suboptions
 		locale		locale names (as output of locale -a)
+		mapclear        buffer argument
 		mapping		mapping name
 		menu		menus
 		messages	|:messages| suboptions

runtime/doc/map.txt

@@ -1227,6 +1227,7 @@ completion can be enabled:
 	-complete=highlight	highlight groups
 	-complete=history	:history suboptions
 	-complete=locale	locale names (as output of locale -a)
+	-complete=mapclear	buffer argument
 	-complete=mapping	mapping name
 	-complete=menu		menus
 	-complete=messages	|:messages| suboptions

src/nvim/ex_docmd.c

@@ -3350,6 +3350,19 @@ const char * set_one_cmd_context(
   case CMD_xunmap:
     return (const char *)set_context_in_map_cmd(
         xp, (char_u *)cmd, (char_u *)arg, forceit, false, true, ea.cmdidx);
+  case CMD_mapclear:
+  case CMD_nmapclear:
+  case CMD_vmapclear:
+  case CMD_omapclear:
+  case CMD_imapclear:
+  case CMD_cmapclear:
+  case CMD_lmapclear:
+  case CMD_smapclear:
+  case CMD_xmapclear:
+    xp->xp_context = EXPAND_MAPCLEAR;
+    xp->xp_pattern = (char_u *)arg;
+    break;
+
   case CMD_abbreviate:    case CMD_noreabbrev:
   case CMD_cabbrev:       case CMD_cnoreabbrev:
   case CMD_iabbrev:       case CMD_inoreabbrev:
@@ -4870,6 +4883,7 @@ static const char *command_complete[] =
 #ifdef HAVE_WORKING_LIBINTL
   [EXPAND_LOCALES] = "locale",
 #endif
+  [EXPAND_MAPCLEAR] = "mapclear",
   [EXPAND_MAPPINGS] = "mapping",
   [EXPAND_MENUS] = "menu",
   [EXPAND_MESSAGES] = "messages",
@@ -9655,6 +9669,14 @@ char_u *get_messages_arg(expand_T *xp FUNC_ATTR_UNUSED, int idx)
   return NULL;
 }
 
+char_u *get_mapclear_arg(expand_T *xp FUNC_ATTR_UNUSED, int idx)
+{
+  if (idx == 0) {
+    return (char_u *)"<buffer>";
+  }
+  return NULL;
+}
+
 static TriState filetype_detect = kNone;
 static TriState filetype_plugin = kNone;
 static TriState filetype_indent = kNone;

src/nvim/ex_getln.c

@@ -4756,6 +4756,7 @@ ExpandFromContext (
     } tab[] = {
       { EXPAND_COMMANDS, get_command_name, false, true },
       { EXPAND_BEHAVE, get_behave_arg, true, true },
+      { EXPAND_MAPCLEAR, get_mapclear_arg, true, true },
       { EXPAND_MESSAGES, get_messages_arg, true, true },
       { EXPAND_HISTORY, get_history_arg, true, true },
       { EXPAND_USER_COMMANDS, get_user_commands, false, true },

src/nvim/testdir/test_cmdline.vim

@@ -222,6 +222,11 @@ func Test_getcompletion()
   let l = getcompletion('not', 'messages')
   call assert_equal([], l)
 
+  let l = getcompletion('', 'mapclear')
+  call assert_true(index(l, '<buffer>') >= 0)
+  let l = getcompletion('not', 'mapclear')
+  call assert_equal([], l)
+
   if has('cscope')
     let l = getcompletion('', 'cscope')
     let cmds = ['add', 'find', 'help', 'kill', 'reset', 'show']

src/nvim/vim.h

@@ -155,6 +155,7 @@ enum {
   EXPAND_USER_ADDR_TYPE,
   EXPAND_PACKADD,
   EXPAND_MESSAGES,
+  EXPAND_MAPCLEAR,
   EXPAND_CHECKHEALTH,
 };