diff: fix 2 whitespace issues

When whitespace or whitespace change was ignored, the function
xdl_recmatch() returned memcmp() style differences, which is wrong,
since it should return 0 on non-match.

Also, there were three horrible off-by-one bugs, even leading to wrong
hashes in the whitespace special handling.

The issue was noticed by Ray Lehtiniemi.

For good measure, this commit adds a test.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 122 insertions, 0 deletions

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
new file mode 100755
index 0000000000..c945085245
--- /dev/null
+++ b/t/t4015-diff-whitespace.sh
@@ -0,0 +1,122 @@
+#!/bin/sh
+#
+# Copyright (c) 2006 Johannes E. Schindelin
+#
+
+test_description='Test special whitespace in diff engine.
+
+'
+. ./test-lib.sh
+. ../diff-lib.sh
+
+# Ray Lehtiniemi's example
+
+cat << EOF > x
+do {
+   nothing;
+} while (0);
+EOF
+
+git-update-index --add x
+
+cat << EOF > x
+do
+{
+   nothing;
+}
+while (0);
+EOF
+
+cat << EOF > expect
+diff --git a/x b/x
+index adf3937..6edc172 100644
+--- a/x
++++ b/x
+@@ -1,3 +1,5 @@
+-do {
++do
++{
+    nothing;
+-} while (0);
++}
++while (0);
+EOF
+
+git-diff > out
+test_expect_success "Ray's example without options" 'diff -u expect out'
+
+git-diff -w > out
+test_expect_success "Ray's example with -w" 'diff -u expect out'
+
+git-diff -b > out
+test_expect_success "Ray's example with -b" 'diff -u expect out'
+
+cat << EOF > x
+whitespace at beginning
+whitespace change
+whitespace in the middle
+whitespace at end
+unchanged line
+CR at end

+EOF
+
+git-update-index x
+
+cat << EOF > x
+	whitespace at beginning
+whitespace 	 change
+white space in the middle
+whitespace at end  
+unchanged line
+CR at end
+EOF
+
+cat << EOF > expect
+diff --git a/x b/x
+index d99af23..8b32fb5 100644
+--- a/x
++++ b/x
+@@ -1,6 +1,6 @@
+-whitespace at beginning
+-whitespace change
+-whitespace in the middle
+-whitespace at end
++	whitespace at beginning
++whitespace 	 change
++white space in the middle
++whitespace at end  
+ unchanged line
+-CR at end

++CR at end
+EOF
+git-diff > out
+test_expect_success 'another test, without options' 'diff -u expect out'
+
+cat << EOF > expect
+diff --git a/x b/x
+index d99af23..8b32fb5 100644
+EOF
+git-diff -w > out
+test_expect_success 'another test, with -w' 'diff -u expect out'
+
+cat << EOF > expect
+diff --git a/x b/x
+index d99af23..8b32fb5 100644
+--- a/x
++++ b/x
+@@ -1,6 +1,6 @@
+-whitespace at beginning
++	whitespace at beginning
+ whitespace change
+-whitespace in the middle
+-whitespace at end
++white space in the middle
++whitespace at end  
+ unchanged line
+-CR at end

++CR at end
+EOF
+git-diff -b > out
+test_expect_success 'another test, with -b' 'diff -u expect out'
+
+test_done