enable support for using `&' in the pattern substitution replacement string

tests/RUN-ONE-TEST

@@ -1,4 +1,4 @@
-BUILD_DIR=/usr/local/build/chet/bash/bash-current
+BUILD_DIR=/usr/local/build/bash/bash-current
 THIS_SH=$BUILD_DIR/bash
 PATH=$PATH:$BUILD_DIR
 

tests/mapfile.right

@@ -151,6 +151,7 @@ a
 [27] aaa
 [28] aaa
 [29] aaa
+declare -a array=([0]="a" [1]="b" [2]="c" [3]=$'\n')
 1 2 3 4 5
 foo 0 1
 

tests/mapfile.tests

@@ -52,6 +52,11 @@ for (( i = 0 ; i < ${#E[@]} ; i++ )); do
     echo "${E[${i}]}"
 done
 
-${THIS_SH} ./mapfile1.sub
+unset -v s array
+s=$'a\xffb\xffc\xff'
+mapfile -t -d $'\xff' array <<<"$s"
+declare -p array
+unset -v s array
 
+${THIS_SH} ./mapfile1.sub
 ${THIS_SH} ./mapfile2.sub

tests/new-exp.right

@@ -617,7 +617,7 @@ c Sub = 0 2 4 8
 <>
 <>
 <'ab '\''cd'\'' ef'> 
-./new-exp10.sub: line 24: ${x@C}: bad substitution
+bash: line 1: ${x@C}: bad substitution
 <'ab'> <'cd ef'> <''> <'gh'> 
 <'ab' 'cd ef' '' 'gh'> 
 <'ab'> <'cd> <ef'> <''> <'gh'> 
@@ -729,6 +729,26 @@ a
 a
 a
 a
+/homes/chetdefg
+/homes/chetdefg
+~defg
+defg
+defg
+defg
+$'a' $'b' $'c' $'d' $'e' $'f' $'g'
+a b c d e f g
+a b c d e f g 
+a b c d e f g
+& & & & & & &
+a a a a a a a 
+3 3 3 3 3 3 3 
+abc defg
+abc defg
+abc defg
+abc defg
+abc defg
+& defg
+& defg
 argv[1] = </>
 argv[1] = </>
 

tests/new-exp.tests

@@ -631,6 +631,10 @@ ${THIS_SH} ./new-exp14.sub
 # ongoing work with a/A parameter transformations and `nounset'
 ${THIS_SH} ./new-exp15.sub
 
+# pattern substitution with `&' (quoted and unquoted) in the replacement string
+${THIS_SH} ./new-exp16.sub
+
+
 # problems with stray CTLNUL in bash-4.0-alpha
 unset a
 a=/a

tests/new-exp10.sub

@@ -21,7 +21,9 @@ printf "<%s>" "${x@A}" ; echo
 x="ab 'cd' ef"
 printf "<%s> " "${x@Q}" ; echo 
 
-printf "<%s>" "${x@C}"
+# this needs to be run in a subshell because invalid transformation operators
+# are now treated as substitution errors, fatal in non-interactive shells
+${THIS_SH} -c 'x=abcdef ; printf "<%s>" "${x@C}"' bash
 
 # if unquoted, normal word splitting happens
 set -- ab 'cd ef' '' gh

tests/new-exp16.sub

@@ -0,0 +1,31 @@
+HOME=/homes/chet
+string=abcdefg
+set -- a b c
+
+# verify existing behavior
+echo ${string/abc/~}
+echo "${string/abc/~}"
+echo ${string/abc/"~"}
+
+echo ${string/abc/$notthere}
+echo "${string/abc/$notthere}"
+echo "${string/abc/"$notthere"}"
+
+echo ${string//?/\$\'&\' } 
+
+echo ${string//?/\& } 
+echo "${string//?/\& }"
+echo ${string//?/"& "}
+echo ${string//?/"\& "}
+
+echo "${string//?/"a "}"
+echo "${string//?/"$# "}"
+
+echo ${string/abc/& }
+echo "${string/abc/& }"
+echo ${string/abc/"& "}
+
+echo ${string/abc/\& }
+echo "${string/abc/\& }"
+echo ${string/abc/"\& "}
+echo ${string/abc/\\& }