patch 9.1.1847: No cmdline completion for :echoconsole and :echowindow

Problem:  No cmdline completion for :echoconsole, :echowindow and second
          expression after :echoerr.
Solution: Set EXPAND_EXPRESSION for :echoconsole and :echowindow, and
          check for multiple expressions after :echoerr (zeertzjq).

closes: #18552

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/cmdexpand.c

@@ -2482,6 +2482,8 @@ set_context_by_cmdname(
 	case CMD_execute:
 	case CMD_echomsg:
 	case CMD_echoerr:
+	case CMD_echoconsole:
+	case CMD_echowindow:
 	case CMD_call:
 	case CMD_return:
 	case CMD_cexpr:

src/eval.c

@@ -3113,6 +3113,8 @@ set_context_for_expression(
 		|| cmdidx == CMD_echo
 		|| cmdidx == CMD_echon
 		|| cmdidx == CMD_echomsg
+		|| cmdidx == CMD_echoerr
+		|| cmdidx == CMD_echoconsole
 		|| cmdidx == CMD_echowindow)
 	    && xp->xp_context == EXPAND_EXPRESSION)
     {

src/testdir/test_cmdline.vim

@@ -1333,11 +1333,12 @@ endfunc
 
 func Test_cmdline_complete_expression()
   let g:SomeVar = 'blah'
-  for cmd in ['exe', 'echo', 'echon', 'echomsg']
+  for cmd in ['exe', 'echo', 'echon', 'echomsg', 'echoerr',
+        \ 'echoconsole', 'echowindow']
     call feedkeys(":" .. cmd .. " SomeV\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_match('"' .. cmd .. ' SomeVar', @:)
+    call assert_match('"' .. cmd .. ' SomeVar', @:, cmd)
     call feedkeys(":" .. cmd .. " foo SomeV\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_match('"' .. cmd .. ' foo SomeVar', @:)
+    call assert_match('"' .. cmd .. ' foo SomeVar', @:, cmd)
   endfor
   unlet g:SomeVar
 endfunc

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1847,
 /**/
     1846,
 /**/