[PATCH/RFC v1 1/1] No duplicate CRLF rewrite warnings on commit

[tboegi@web.de]

From: Torsten Bögershausen <tboegi@web.de>

If .gitattributes are used to enable CRLF->LF rewriting,
then commiting a file that would have its line endings rewritten,
the "CRLF will be replaced by LF" warning is printed 2 times.
A user expects it to be printed only once.
The automatic rename detection by Git runs the conversion twice,
suppress the warning in the second run.

Reported-By: Adam Dinwoodie <adam@dinwoodie.org>
Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---
 diff.c           |  2 ++
 diffcore-break.c |  6 ++++--
 diffcore.h       |  1 +
 t/t0020-crlf.sh  | 14 ++++++++++++++
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/diff.c b/diff.c
index d3734d3..c965afc 100644
--- a/diff.c
+++ b/diff.c
@@ -2749,6 +2749,8 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 	enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
 				    ? SAFE_CRLF_WARN
 				    : safe_crlf);
+	if (flags & CHECK_IGNORE_CRLF_WARNING)
+		crlf_warn = SAFE_CRLF_FALSE;
 
 	if (!DIFF_FILE_VALID(s))
 		die("internal error: asking to populate invalid file.");
diff --git a/diffcore-break.c b/diffcore-break.c
index 5473493..4a75681 100644
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -47,6 +47,7 @@ static int should_break(struct diff_filespec *src,
 	 */
 	unsigned long delta_size, max_size;
 	unsigned long src_copied, literal_added, src_removed;
+	unsigned flags2 = 0;
 
 	*merge_score_p = 0; /* assume no deletion --- "do not break"
 			     * is the default.
@@ -61,9 +62,10 @@ static int should_break(struct diff_filespec *src,
 	    !hashcmp(src->sha1, dst->sha1))
 		return 0; /* they are the same */
 
-	if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
+	if (!strcmp(src->path, dst->path))
+		flags2 = CHECK_IGNORE_CRLF_WARNING;
+	if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, flags2))
 		return 0; /* error but caught downstream */
-
 	max_size = ((src->size > dst->size) ? src->size : dst->size);
 	if (max_size < MINIMUM_BREAK_SIZE)
 		return 0; /* we do not break too small filepair */
diff --git a/diffcore.h b/diffcore.h
index 33ea2de..91464aa 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -57,6 +57,7 @@ extern void fill_filespec(struct diff_filespec *, const unsigned char *,
 
 #define CHECK_SIZE_ONLY 1
 #define CHECK_BINARY    2
+#define CHECK_IGNORE_CRLF_WARNING    4
 extern int diff_populate_filespec(struct diff_filespec *, unsigned int);
 extern void diff_free_filespec_data(struct diff_filespec *);
 extern void diff_free_filespec_blob(struct diff_filespec *);
diff --git a/t/t0020-crlf.sh b/t/t0020-crlf.sh
index f94120a..f7d2f74 100755
--- a/t/t0020-crlf.sh
+++ b/t/t0020-crlf.sh
@@ -86,6 +86,20 @@ test_expect_success 'safecrlf: print warning only once' '
 	test $(git add doublewarn 2>&1 | grep "CRLF will be replaced by LF" | wc -l) = 1
 '
 
+test_expect_success 'safecrlf: print warning only once on commit' '
+
+	git config core.autocrlf input &&
+	git config core.safecrlf warn &&
+
+	for w in I am all LF; do echo $w; done >doublewarn2 &&
+	git add doublewarn2 &&
+	git commit -m "nowarn" &&
+	for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >doublewarn2 &&
+	git add doublewarn2 2>&1 &&
+	git commit -m Message 2>&1 | grep "CRLF will be replaced by LF" >actual &&
+	echo "warning: CRLF will be replaced by LF in doublewarn2." >expected &&
+	test_cmp expected actual
+'
 
 test_expect_success 'safecrlf: git diff demotes safecrlf=true to warn' '
 	git config core.autocrlf input &&
-- 
2.0.0.rc1.6318.g0c2c796