chainlint.sed: stop throwing away here-doc tags

The purpose of chainlint is to highlight problems it finds in test code
by inserting annotations at the location of each problem. Arbitrarily
eliding bits of the code it is checking is not helpful, yet this is
exactly what chainlint.sed does by cavalierly and unnecessarily dropping
the here-doc operator and tag; i.e. `cat <<TAG` becomes simply `cat` in
the output. This behavior can make it more difficult for the test writer
to align the annotated output of chainlint.sed with the original test
code. Address this by retaining here-doc tags.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/chainlint.sed

@@ -62,20 +62,20 @@
 # receives similar treatment.
 #
 # Swallowing here-docs with arbitrary tags requires a bit of finesse. When a
-# line such as "cat <<EOF >out" is seen, the here-doc tag is moved to the front
-# of the line enclosed in angle brackets as a sentinel, giving "<EOF>cat >out".
+# line such as "cat <<EOF" is seen, the here-doc tag is copied to the front of
+# the line enclosed in angle brackets as a sentinel, giving "<EOF>cat <<EOF".
 # As each subsequent line is read, it is appended to the target line and a
 # (whitespace-loose) back-reference match /^<(.*)>\n\1$/ is attempted to see if
 # the content inside "<...>" matches the entirety of the newly-read line. For
 # instance, if the next line read is "some data", when concatenated with the
-# target line, it becomes "<EOF>cat >out\nsome data", and a match is attempted
+# target line, it becomes "<EOF>cat <<EOF\nsome data", and a match is attempted
 # to see if "EOF" matches "some data". Since it doesn't, the next line is
 # attempted. When a line consisting of only "EOF" (and possible whitespace) is
-# encountered, it is appended to the target line giving "<EOF>cat >out\nEOF",
+# encountered, it is appended to the target line giving "<EOF>cat <<EOF\nEOF",
 # in which case the "EOF" inside "<...>" does match the text following the
 # newline, thus the closing here-doc tag has been found. The closing tag line
 # and the "<...>" prefix on the target line are then discarded, leaving just
-# the target line "cat >out".
+# the target line "cat <<EOF".
 #------------------------------------------------------------------------------
 
 # incomplete line -- slurp up next line
@@ -90,8 +90,7 @@
 # command to which it was attached)
 /<<-*[ 	]*[\\'"]*[A-Za-z0-9_]/ {
 	/"[^"]*<<[^"]*"/bnotdoc
-	s/^\(.*\)<<-*[ 	]*[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1<</
-	s/[ 	]*<<//
+	s/^\(.*<<-*[ 	]*\)[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1\2/
 	:hered
 	N
 	/^<\([^>]*\)>.*\n[ 	]*\1[ 	]*$/!{
@@ -238,6 +237,7 @@ s/.*\n//
 :cont
 # retrieve and print previous line
 x
+s/?!HERE?!/<</g
 n
 bslurp
 
@@ -278,8 +278,7 @@ bfolded
 # found here-doc -- swallow it to avoid false hits within its body (but keep
 # the command to which it was attached)
 :heredoc
-s/^\(.*\)<<-*[ 	]*[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\2>\1<</
-s/[ 	]*<<//
+s/^\(.*\)<<\(-*[ 	]*\)[\\'"]*\([A-Za-z0-9_][A-Za-z0-9_]*\)['"]*/<\3>\1?!HERE?!\2\3/
 :hdocsub
 N
 /^<\([^>]*\)>.*\n[ 	]*\1[ 	]*$/!{
@@ -293,6 +292,7 @@ bfolded
 # found "case ... in" -- pass through untouched
 :case
 x
+s/?!HERE?!/<</g
 n
 /^[ 	]*esac/bslurp
 bcase
@@ -320,6 +320,7 @@ bchkchn
 :nest
 x
 :nstslrp
+s/?!HERE?!/<</g
 n
 # closing ")" on own line -- stop nested slurp
 /^[ 	]*)/bnstcl
@@ -342,6 +343,7 @@ bchkchn
 # found multi-line "{...\n...}" block -- pass through untouched
 :block
 x
+s/?!HERE?!/<</g
 n
 # closing "}" -- stop block slurp
 /}/bchkchn
@@ -352,13 +354,17 @@ bblock
 :clssolo
 x
 s/\( ?!AMP?!\)* ?!AMP?!$//
+s/?!HERE?!/<</g
 p
 x
+s/?!HERE?!/<</g
 b
 
 # found closing "...)" -- exit subshell loop
 :close
 x
+s/?!HERE?!/<</g
 p
 x
+s/?!HERE?!/<</g
 b

t/chainlint/for-loop.expect

@@ -2,7 +2,7 @@
 	for i in a b c
 	do
 		echo $i ?!AMP?!
-		cat
+		cat <<-EOF
 	done ?!AMP?!
 	for i in a b c; do
 		echo $i &&

t/chainlint/here-doc-close-subshell.expect

@@ -1,2 +1,2 @@
 (
-	cat)
+	cat <<-INPUT)

t/chainlint/here-doc-multi-line-command-subst.expect

@@ -1,5 +1,5 @@
 (
-	x=$(bobble &&
+	x=$(bobble <<-END &&
 		wiffle) ?!AMP?!
 	echo $x
 )

t/chainlint/here-doc-multi-line-string.expect

@@ -1,4 +1,4 @@
 (
-	cat && echo "multi-line	string" ?!AMP?!
+	cat <<-TXT && echo "multi-line	string" ?!AMP?!
 	bap
 )

t/chainlint/here-doc.expect

@@ -1,7 +1,7 @@
-boodle wobba        gorgo snoot        wafta snurb &&
+boodle wobba        gorgo snoot        wafta snurb <<EOF &&
 
-cat >foo &&
+cat <<-Arbitrary_Tag_42 >foo &&
 
-cat >boo &&
+cat <<zump >boo &&
 
-horticulture
+horticulture <<EOF

t/chainlint/if-then-else.expect

@@ -8,7 +8,7 @@
 		echo foo
 	else
 		echo foo &&
-		cat
+		cat <<-EOF
 	fi ?!AMP?!
 	echo poodle
 ) &&

t/chainlint/nested-here-doc.expect

@@ -1,7 +1,7 @@
-cat >foop &&
+cat <<ARBITRARY >foop &&
 
 (
-	cat &&
-	cat ?!AMP?!
+	cat <<-INPUT_END &&
+	cat <<-EOT ?!AMP?!
 	foobar
 )

t/chainlint/subshell-here-doc.expect

@@ -1,10 +1,10 @@
 (
-	echo wobba 	       gorgo snoot 	       wafta snurb &&
-	cat >bip ?!AMP?!
-	echo >bop
+	echo wobba 	       gorgo snoot 	       wafta snurb <<-EOF &&
+	cat <<EOF >bip ?!AMP?!
+	echo <<-EOF >bop
 ) &&
 (
-	cat >bup &&
-	cat >bup3 &&
+	cat <<-ARBITRARY >bup &&
+	cat <<-ARBITRARY3 >bup3 &&
 	meep
 )

t/chainlint/t7900-subtree.expect

@@ -1,9 +1,9 @@
 (
 	chks="sub1sub2sub3sub4" &&
-	chks_sub=$(cat | sed "s,^,sub dir/,"
+	chks_sub=$(cat <<TXT | sed "s,^,sub dir/,"
 ) &&
 	chkms="main-sub1main-sub2main-sub3main-sub4" &&
-	chkms_sub=$(cat | sed "s,^,sub dir/,"
+	chkms_sub=$(cat <<TXT | sed "s,^,sub dir/,"
 ) &&
 	subfiles=$(git ls-files) &&
 	check_equal "$subfiles" "$chkms$chks"

t/chainlint/while-loop.expect

@@ -2,7 +2,7 @@
 	while true
 	do
 		echo foo ?!AMP?!
-		cat
+		cat <<-EOF
 	done ?!AMP?!
 	while true; do
 		echo foo &&