patch 8.2.2206: :exe command line completion only works for first argument

Problem:    :exe command line completion only works for first argument.
Solution:   Skip over text if more is following. (closes #7546)

src/eval.c

@@ -1904,6 +1904,24 @@ set_context_for_expression(
 	    while ((c = *++arg) != NUL && (c == ' ' || c == '\t'))
 		/* skip */ ;
     }
+
+    // ":exe one two" completes "two"
+    if ((cmdidx == CMD_execute
+		|| cmdidx == CMD_echo
+		|| cmdidx == CMD_echon
+		|| cmdidx == CMD_echomsg)
+	    && xp->xp_context == EXPAND_EXPRESSION)
+    {
+	for (;;)
+	{
+	    char_u *n = skiptowhite(arg);
+
+	    if (n == arg || IS_WHITE_OR_NUL(*skipwhite(n)))
+		break;
+	    arg = skipwhite(n);
+	}
+    }
+
     xp->xp_pattern = arg;
 }
 

src/testdir/test_cmdline.vim

@@ -673,6 +673,17 @@ func Test_cmdline_complete_env_variable()
   unlet $X_VIM_TEST_COMPLETE_ENV
 endfunc
 
+func Test_cmdline_complete_expression()
+  let g:SomeVar = 'blah'
+  for cmd in ['exe', 'echo', 'echon', 'echomsg']
+    call feedkeys(":" .. cmd .. " SomeV\<Tab>\<C-B>\"\<CR>", 'tx')
+    call assert_match('"' .. cmd .. ' SomeVar', @:)
+    call feedkeys(":" .. cmd .. " foo SomeV\<Tab>\<C-B>\"\<CR>", 'tx')
+    call assert_match('"' .. cmd .. ' foo SomeVar', @:)
+  endfor
+  unlet g:SomeVar
+endfunc
+
 " Test for various command-line completion
 func Test_cmdline_complete_various()
   " completion for a command starting with a comment

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2206,
 /**/
     2205,
 /**/