tr portability fixes

Specifying character ranges in tr differs between System V
and POSIX. In System V, brackets are required (e.g.,
'[A-Z]'), whereas in POSIX they are not.

We can mostly get around this by just using the bracket form
for both sets, as in:

  tr '[A-Z] '[a-z]'

in which case POSIX interpets this as "'[' becomes '['",
which is OK.

However, this doesn't work with multiple sequences, like:

  # rot13
  tr '[A-Z][a-z]' '[N-Z][A-M][n-z][a-m]'

where the POSIX version does not behave the same as the
System V version. In this case, we must simply enumerate the
sequence.

This patch fixes problematic uses of tr in git scripts and
test scripts in one of three ways:

  - if a single sequence, make sure it uses brackets
  - if multiple sequences, enumerate
  - if extra brackets (e.g., tr '[A]' 'a'), eliminate
    brackets

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-bisect.sh

@@ -293,14 +293,14 @@ bisect_next() {
 	bisect_next_check good
 
 	skip=$(git for-each-ref --format='%(objectname)' \
-		"refs/bisect/skip-*" | tr '[\012]' ' ') || exit
+		"refs/bisect/skip-*" | tr '\012' ' ') || exit
 
 	BISECT_OPT=''
 	test -n "$skip" && BISECT_OPT='--bisect-all'
 
 	bad=$(git rev-parse --verify refs/bisect/bad) &&
 	good=$(git for-each-ref --format='^%(objectname)' \
-		"refs/bisect/good-*" | tr '[\012]' ' ') &&
+		"refs/bisect/good-*" | tr '\012' ' ') &&
 	eval="git rev-list --bisect-vars $BISECT_OPT $good $bad --" &&
 	eval="$eval $(cat "$GIT_DIR/BISECT_NAMES")" &&
 	eval=$(filter_skipped "$eval" "$skip") &&

git-filter-branch.sh

@@ -58,8 +58,8 @@ eval "$functions"
 # "author" or "committer
 
 set_ident () {
-	lid="$(echo "$1" | tr "A-Z" "a-z")"
+	lid="$(echo "$1" | tr "[A-Z]" "[a-z]")"
-	uid="$(echo "$1" | tr "a-z" "A-Z")"
+	uid="$(echo "$1" | tr "[a-z]" "[A-Z]")"
 	pick_id_script='
 		/^'$lid' /{
 			s/'\''/'\''\\'\'\''/g

t/t4022-diff-rewrite.sh

@@ -8,7 +8,10 @@ test_expect_success setup '
 
 	cat ../../COPYING >test &&
 	git add test &&
-	tr 'a-zA-Z' 'n-za-mN-ZA-M' <../../COPYING >test
+	tr \
+	  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+	  "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM" \
+	  <../../COPYING >test
 
 '
 

t/t7003-filter-branch.sh

@@ -4,7 +4,7 @@ test_description='git-filter-branch'
 . ./test-lib.sh
 
 make_commit () {
-	lower=$(echo $1 | tr A-Z a-z)
+	lower=$(echo $1 | tr '[A-Z]' '[a-z]')
 	echo $lower > $lower
 	git add $lower
 	test_tick