main: Highlight unknown precommand option as unknown-token

highlighters/main/main-highlighter.zsh

@@ -612,12 +612,24 @@ _zsh_highlight_main_highlighter_highlight_list()
           # Flag that requires an argument
           this_word=${this_word//:start:/}
           next_word=':sudo_arg:'
-        elif [[ $arg == '-'* ]]; then
-          # Flag that requires no argument, or unknown flag.
-          # This prevents misbehavior with sudo -u -otherargument
+        elif [[ -n $flags_with_argument ]] &&
+             [[ $arg == '-'[$flags_sans_argument]#[$flags_with_argument]* ]]; then
+          # Argument attached in the same word
           this_word=${this_word//:start:/}
           next_word+=':start:'
           next_word+=':sudo_opt:'
+        elif [[ $arg == '-'[$flags_sans_argument]# ]]; then
+          # Flag that requires no argument
+          this_word=:sudo_opt:
+          next_word+=':start:'
+          next_word+=':sudo_opt:'
+        elif [[ $arg == '-'* ]]; then
+          # Unknown flag
+          this_word=:sudo_opt:
+          next_word+=':start:'
+          next_word+=':sudo_opt:'
+          _zsh_highlight_main_add_region_highlight $start_pos $end_pos unknown-token
+          continue
         else
           # Not an option flag; nothing to do.  (If the command line is
           # syntactically valid, ${this_word//:sudo_opt:/} should be

highlighters/main/test-data/precommand-unknown-option.zsh

@@ -0,0 +1,43 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2018 zsh-syntax-highlighting contributors
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted
+# provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice, this list of conditions
+#    and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice, this list of
+#    conditions and the following disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
+#    may be used to endorse or promote products derived from this software without specific prior
+#    written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -------------------------------------------------------------------------------------------------
+# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
+# vim: ft=zsh sw=2 ts=2 et
+# -------------------------------------------------------------------------------------------------
+
+sudo(){}
+
+BUFFER='sudo -ux ls; sudo -x ls'
+
+expected_region_highlight=(
+  '1 4 precommand' # sudo
+  '6 8 single-hyphen-option' # -ux
+  '10 11 command' # ls
+  '12 12 commandseparator' # ;
+  '14 17 precommand' # sudo
+  '19 20 unknown-token' # -x
+  '22 23 command' # ls
+)