patch 9.0.0346: :horizontal modifier not fully supported

Problem:    :horizontal modifier not fully supported.
Solution:   Also use :horizontal for completion and user commands.
            (closes #11025)

src/cmdexpand.c

@@ -1776,6 +1776,7 @@ set_context_by_cmdname(
 	case CMD_folddoclosed:
 	case CMD_folddoopen:
 	case CMD_hide:
+	case CMD_horizontal:
 	case CMD_keepalt:
 	case CMD_keepjumps:
 	case CMD_keepmarks:

src/ex_docmd.c

@@ -2455,6 +2455,7 @@ do_one_cmd(
 	    case CMD_final:
 	    case CMD_help:
 	    case CMD_hide:
+	    case CMD_horizontal:
 	    case CMD_ijump:
 	    case CMD_ilist:
 	    case CMD_isearch:

src/testdir/test_cmdline.vim

@@ -1078,6 +1078,10 @@ func Test_cmdline_complete_various()
   call feedkeys(":all abc\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"all abc\<C-A>", @:)
 
+  " completion for :wincmd with :horizontal modifier
+  call feedkeys(":horizontal wincm\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"horizontal wincmd", @:)
+
   " completion for a command with a command modifier
   call feedkeys(":topleft new\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"topleft new", @:)

src/testdir/test_usercommands.vim

@@ -103,6 +103,10 @@ function Test_cmdmods()
   call assert_equal('vertical', g:mods)
   vert MyCmd
   call assert_equal('vertical', g:mods)
+  horizontal MyCmd
+  call assert_equal('horizontal', g:mods)
+  hor MyCmd
+  call assert_equal('horizontal', g:mods)
 
   aboveleft belowright botright browse confirm hide keepalt keepjumps
 	      \ keepmarks keeppatterns lockmarks noautocmd noswapfile silent

src/usercmd.c

@@ -1443,6 +1443,9 @@ add_win_cmd_modifers(char_u *buf, cmdmod_T *cmod, int *multi_mods)
     // :vertical
     if (cmod->cmod_split & WSP_VERT)
 	result += add_cmd_modifier(buf, "vertical", multi_mods);
+    // :horizontal
+    if (cmod->cmod_split & WSP_HOR)
+	result += add_cmd_modifier(buf, "horizontal", multi_mods);
     return result;
 }
 

src/version.c

@@ -707,6 +707,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    346,
 /**/
     345,
 /**/