fix for parameter length expressions for nameref variables expanding to invalid identifiers

tests/nameref24.sub

@@ -0,0 +1,42 @@
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# issues with taking the length of nameref variables
+#
+# just the basics
+
+scalar=foo
+declare -a array=(foo)
+
+declare -n name=array
+declare -n name1=array[0]
+declare -n name2=unset
+declare -n name3=
+declare -n name4='a&b'
+
+echo ${#name}	# length of nameref resolving to set variable
+echo ${#name1}	# length of nameref resolving to valid non-identifier
+echo ${#name2}	# length of nameref resolving to unset variable
+echo ${#name3}	# length of nameref resolving to empty string
+echo ${#name4}	# length of nameref resolving to invalid non-identifier
+
+unset -n name name1
+
+declare -n name=scalar
+declare -n name1=scalar[0]
+name4='aa&bb'
+declare -n name4
+
+echo ${#name}	# length of nameref resolving to set variable
+echo ${#name1}	# length of nameref resolving to valid non-identifier
+echo ${#name4}	# length of nameref resolving to invalid non-identifier