'main': Highlight several more special (non-alphabetic) parameters.

highlighters/main/main-highlighter.zsh

@@ -760,6 +760,10 @@ _zsh_highlight_main_highlighter_highlight_string()
               # $$ - pid
               (( k += 1 )) # highlight both dollar signs
               (( i += 1 )) # don't consider the second one as introducing another parameter expansion
+            elif [[ $arg[i+1] == [-#*@?] ]]; then
+              # $#, $*, $@, $?, $- - like $$ above
+              (( k += 1 )) # highlight both dollar signs
+              (( i += 1 )) # don't consider the second one as introducing another parameter expansion
             elif [[ $arg[i+1] == $'\x28' ]]; then
               # Highlight just the '$'.
             else

highlighters/main/test-data/dollar-noise.zsh

@@ -0,0 +1,46 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2016 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
+# -------------------------------------------------------------------------------------------------
+
+BUFFER=': "$- $# $* $@ $?"'
+
+expected_region_highlight=(
+  '1 1 builtin' # :
+  '3 3 double-quoted-argument' # "
+  '4 5 dollar-double-quoted-argument' # $-
+  '6 6 double-quoted-argument' # <space>
+  '7 8 dollar-double-quoted-argument' # $#
+  '9 9 double-quoted-argument' # <space>
+  '10 11 dollar-double-quoted-argument' # $*
+  '12 12 double-quoted-argument' # <space>
+  '13 14 dollar-double-quoted-argument' # $@
+  '15 15 double-quoted-argument' # <space>
+  '16 17 dollar-double-quoted-argument' # $?
+  '18 18 double-quoted-argument' # "
+)