diffcore-delta.c: Ignore CR in CRLF for text files

This ignores CR byte in CRLF sequence in text file when
computing similarity of two blobs.

Usually this should not matter as nobody sane would be checking
in a file with CRLF line endings to the repository (they would
use autocrlf so that the repository copy would have LF line
endings).

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-delta.c

@@ -122,11 +122,14 @@ static struct spanhash_top *add_spanhash(struct spanhash_top *top,
 	}
 }
 
-static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz)
+static struct spanhash_top *hash_chars(struct diff_filespec *one)
 {
 	int i, n;
 	unsigned int accum1, accum2, hashval;
 	struct spanhash_top *hash;
+	unsigned char *buf = one->data;
+	unsigned int sz = one->size;
+	int is_text = !one->is_binary;
 
 	i = INITIAL_HASH_SIZE;
 	hash = xmalloc(sizeof(*hash) + sizeof(struct spanhash) * (1<<i));
@@ -140,6 +143,11 @@ static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz)
 		unsigned int c = *buf++;
 		unsigned int old_1 = accum1;
 		sz--;
+
+		/* Ignore CR in CRLF sequence if text */
+		if (is_text && c == '\r' && sz && *buf == '\n')
+			continue;
+
 		accum1 = (accum1 << 7) ^ (accum2 >> 25);
 		accum2 = (accum2 << 7) ^ (old_1 >> 25);
 		accum1 += c;
@@ -169,14 +177,14 @@ int diffcore_count_changes(struct diff_filespec *src,
 	if (src_count_p)
 		src_count = *src_count_p;
 	if (!src_count) {
-		src_count = hash_chars(src->data, src->size);
+		src_count = hash_chars(src);
 		if (src_count_p)
 			*src_count_p = src_count;
 	}
 	if (dst_count_p)
 		dst_count = *dst_count_p;
 	if (!dst_count) {
-		dst_count = hash_chars(dst->data, dst->size);
+		dst_count = hash_chars(dst);
 		if (dst_count_p)
 			*dst_count_p = dst_count;
 	}

t/t0022-crlf-rename.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+test_description='ignore CR in CRLF sequence while computing similiarity'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	cat ../t0022-crlf-rename.sh >sample &&
+	git add sample &&
+
+	test_tick &&
+	git commit -m Initial &&
+
+	sed -e "s/\$/
/" ../t0022-crlf-rename.sh >elpmas &&
+	git add elpmas &&
+	rm -f sample &&
+
+	test_tick &&
+	git commit -a -m Second
+
+'
+
+test_expect_success 'diff -M' '
+
+	git diff-tree -M -r --name-status HEAD^ HEAD |
+	sed -e "s/R[0-9]*/RNUM/" >actual &&
+	echo "RNUM	sample	elpmas" >expect &&
+	diff -u expect actual
+
+'
+
+test_done