Merge branch 'jc/whitespace-incomplete-line' into jch

It does not make much sense to apply the "incomplete-line"
whitespace rule to symbolic links, whose contents almost always
lack the final newline.  "git apply" and "git diff" are now taught
to exclude them for a change to symbolic links.

* jc/whitespace-incomplete-line:
  whitespace: symbolic links usually lack LF at the end

apply.c

@@ -1725,6 +1725,26 @@ static int parse_fragment(struct apply_state *state,
 	unsigned long oldlines, newlines;
 	unsigned long leading, trailing;
 
+	/* do not complain a symbolic link being an incomplete line */
+	if (patch->ws_rule & WS_INCOMPLETE_LINE) {
+		/*
+		 * We want to figure out if the postimage is a
+		 * symbolic link when applying the patch normally, or
+		 * if the preimage is a symbolic link when applying
+		 * the patch in reverse.  A normal patch only has
+		 * old_mode without new_mode.  If it changes the
+		 * filemode, new_mode has value, which is different
+		 * from old_mode.
+		 */
+		unsigned mode = (state->apply_in_reverse
+				 ? patch->old_mode
+				 : patch->new_mode
+				 ? patch->new_mode
+				 : patch->old_mode);
+		if (mode && S_ISLNK(mode))
+			patch->ws_rule &= ~WS_INCOMPLETE_LINE;
+	}
+
 	offset = parse_fragment_header(line, len, fragment);
 	if (offset < 0)
 		return -1;

diff.c

@@ -1837,6 +1837,7 @@ static void emit_rewrite_diff(const char *name_a,
 	const char *a_prefix, *b_prefix;
 	char *data_one, *data_two;
 	size_t size_one, size_two;
+	unsigned ws_rule;
 	struct emit_callback ecbdata;
 	struct strbuf out = STRBUF_INIT;
 
@@ -1859,9 +1860,15 @@ static void emit_rewrite_diff(const char *name_a,
 	size_one = fill_textconv(o->repo, textconv_one, one, &data_one);
 	size_two = fill_textconv(o->repo, textconv_two, two, &data_two);
 
+	ws_rule = whitespace_rule(o->repo->index, name_b);
+
+	/* symlink being an incomplete line is not a news */
+	if (DIFF_FILE_VALID(two) && S_ISLNK(two->mode))
+		ws_rule &= ~WS_INCOMPLETE_LINE;
+
 	memset(&ecbdata, 0, sizeof(ecbdata));
 	ecbdata.color_diff = o->use_color;
-	ecbdata.ws_rule = whitespace_rule(o->repo->index, name_b);
+	ecbdata.ws_rule = ws_rule;
 	ecbdata.opt = o;
 	if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
 		mmfile_t mf1, mf2;
@@ -3759,6 +3766,7 @@ static void builtin_diff(const char *name_a,
 		xpparam_t xpp;
 		xdemitconf_t xecfg;
 		struct emit_callback ecbdata;
+		unsigned ws_rule;
 		const struct userdiff_funcname *pe;
 
 		if (must_show_header) {
@@ -3770,6 +3778,12 @@ static void builtin_diff(const char *name_a,
 		mf1.size = fill_textconv(o->repo, textconv_one, one, &mf1.ptr);
 		mf2.size = fill_textconv(o->repo, textconv_two, two, &mf2.ptr);
 
+		ws_rule = whitespace_rule(o->repo->index, name_b);
+
+		/* symlink being an incomplete line is not a news */
+		if (DIFF_FILE_VALID(two) && S_ISLNK(two->mode))
+			ws_rule &= ~WS_INCOMPLETE_LINE;
+
 		pe = diff_funcname_pattern(o, one);
 		if (!pe)
 			pe = diff_funcname_pattern(o, two);
@@ -3781,7 +3795,7 @@ static void builtin_diff(const char *name_a,
 			lbl[0] = NULL;
 		ecbdata.label_path = lbl;
 		ecbdata.color_diff = o->use_color;
-		ecbdata.ws_rule = whitespace_rule(o->repo->index, name_b);
+		ecbdata.ws_rule = ws_rule;
 		if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
 			check_blank_at_eof(&mf1, &mf2, &ecbdata);
 		ecbdata.opt = o;
@@ -3988,6 +4002,10 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
 	data.ws_rule = whitespace_rule(o->repo->index, attr_path);
 	data.conflict_marker_size = ll_merge_marker_size(o->repo->index, attr_path);
 
+	/* symlink being an incomplete line is not a news */
+	if (DIFF_FILE_VALID(two) && S_ISLNK(two->mode))
+		data.ws_rule &= ~WS_INCOMPLETE_LINE;
+
 	if (fill_mmfile(o->repo, &mf1, one) < 0 ||
 	    fill_mmfile(o->repo, &mf2, two) < 0)
 		die("unable to read files to diff");

t/t4015-diff-whitespace.sh

@@ -90,6 +90,32 @@ test_expect_success "new incomplete line in post-image" '
 	git -c core.whitespace=incomplete diff -R --check x
 '
 
+test_expect_success SYMLINKS "incomplete-line error is disabled for symlinks" '
+	test_when_finished "git reset --hard" &&
+	test_when_finished "rm -f mylink" &&
+
+	# a regular file with an incomplete line
+	printf "%s" one >mylink &&
+	git add mylink &&
+
+	# a symbolic link
+	rm mylink &&
+	ln -s two mylink &&
+
+	git -c diff.color=always -c core.whitespace=incomplete \
+		diff mylink >forward.raw &&
+	test_decode_color >forward <forward.raw &&
+	test_grep ! "<BRED>\\\\ No newline at end of file<RESET>" forward &&
+
+	git -c diff.color=always -c core.whitespace=incomplete \
+		diff -R mylink >reverse.raw &&
+	test_decode_color >reverse <reverse.raw &&
+	test_grep "<BRED>\\\\ No newline at end of file<RESET>" reverse &&
+
+	git -c core.whitespace=incomplete diff --check mylink &&
+	test_must_fail git -c core.whitespace=incomplete diff --check -R mylink
+'
+
 test_expect_success "Ray Lehtiniemi's example" '
 	cat <<-\EOF >x &&
 	do {

t/t4124-apply-ws-rule.sh

@@ -743,4 +743,90 @@ test_expect_success 'incomplete line modified at the end (error)' '
 	test_cmp sample target
 '
 
+test_expect_success "incomplete-line error is disabled for symlinks" '
+	test_when_finished "git reset" &&
+	test_when_finished "rm -f patch.txt" &&
+	oneblob=$(printf "one" | git hash-object --stdin -w -t blob) &&
+	twoblob=$(printf "two" | git hash-object --stdin -w -t blob) &&
+
+	oneshort=$(git rev-parse --short $oneblob) &&
+	twoshort=$(git rev-parse --short $twoblob) &&
+
+	cat >patch0.txt <<-EOF &&
+	diff --git a/mylink b/mylink
+	index $oneshort..$twoshort 120000
+	--- a/mylink
+	+++ b/mylink
+	@@ -1 +1 @@
+	-one
+	\ No newline at end of file
+	+two
+	\ No newline at end of file
+	EOF
+
+	# the index has the preimage symlink
+	git update-index --add --cacheinfo "120000,$oneblob,mylink" &&
+
+	# check the patch going forward and reverse
+	git -c core.whitespace=incomplete apply --cached --check \
+		--whitespace=error patch0.txt &&
+
+	git update-index --add --cacheinfo "120000,$twoblob,mylink" &&
+	git -c core.whitespace=incomplete apply --cached --check \
+		--whitespace=error -R patch0.txt &&
+
+	# the patch turns it into the postimage symlink
+	git update-index --add --cacheinfo "120000,$oneblob,mylink" &&
+	git -c core.whitespace=incomplete apply --cached --whitespace=error \
+		patch0.txt &&
+
+	# and then back.
+	git -c core.whitespace=incomplete apply --cached -R --whitespace=error \
+		patch0.txt &&
+
+	# a text file turns into a symlink
+	cat >patch1.txt <<-EOF &&
+	diff --git a/mylink b/mylink
+	deleted file mode 100644
+	index $oneshort..0000000
+	--- a/mylink
+	+++ /dev/null
+	@@ -1 +0,0 @@
+	-one
+	\ No newline at end of file
+	diff --git a/mylink b/mylink
+	new file mode 120000
+	index 0000000..$twoshort
+	--- /dev/null
+	+++ b/mylink
+	@@ -0,0 +1 @@
+	+two
+	\ No newline at end of file
+	EOF
+
+	# the index has the preimage text
+	git update-index --cacheinfo "100644,$oneblob,mylink" &&
+
+	# check
+	git -c core.whitespace=incomplete apply --cached \
+		--check --whitespace=error patch1.txt &&
+
+	# reverse, leaving an incomplete text file, should error
+	git update-index --cacheinfo "120000,$twoblob,mylink" &&
+	test_must_fail git -c core.whitespace=incomplete \
+		apply --cached --check --whitespace=error -R patch1.txt &&
+
+	# apply to create a symbolic link
+	git update-index --cacheinfo "100644,$oneblob,mylink" &&
+	git -c core.whitespace=incomplete apply --cached --whitespace=error \
+		patch1.txt &&
+
+	# turning it back into an incomplete text file is an error
+	test_must_fail git -c core.whitespace=incomplete \
+		apply --cached --whitespace=error -R patch1.txt
+
+
+
+'
+
 test_done