correct ce_compare_data() in a middle of a mergetb/convert-peek-in-index

The following didn't work as expected:

 - In a middle of a merge
 - merge.renormalize is true,
 - .gitattributes = "* text=auto"
 - core.eol = crlf

Merge a blob with CRLF "first line\r\nsame line\r\n" and a blob
with LF "first line\nsame line\n".

The expected result of the merge is "first line\nsame line\n".

The content in the working tree is "first line\r\nsame line\r\n",
and ce_compare_data() should find that the content is clean and return 0.

Deep down crlf_to_git() is invoked, to check if CRLF are converted or not.

The "new safer autocrlf handling" calls blob_has_cr().

Instead of using the sha1 of the blob, (CRLF in this example),
the function get_sha1_from_index() is invoked.
get_sha1_from_index() decides to return "ours" when in the middle of
the merge, which is LF.

As a result, the CRLF in the worktree are converted into LF before
the comparison.
The contents of LF and CRLF don't match any more.

The problem is that ce_compare_data() has ce->sha1, but the sha1 is lost
on it's way into blob_has_cr().

Forwarding ce->sha1 from ce_compare_data() into crlf_to_git() makes sure
that blob_has_cr() looks at the appropriate blob.

Add a new parameter index_blob_sha1 to convert_to_git(), and forward the
sha1 from ce_compare_data() into convert_to_git(). Other callers use NULL
for index_blob_sha1, and the sha1 is determined from path
using get_sha1_from_cache(path). This is the same handling as before.

In the same spirit, forward the sha1 into would_convert_to_git().

While at it, rename has_cr_in_index() into blob_has_cr()
and replace 0 with SAFE_CRLF_FALSE.

Add a TC in t6038 to have a test coverage under Linux.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/diff.c b/diff.c
index 059123c5dc..b97346960f 100644
--- a/diff.c
+++ b/diff.c
@@ -2800,7 +2800,8 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
 		/*
 		 * Convert from working tree format to canonical git format
 		 */
-		if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
+		if (convert_to_git(s->path, s->data, s->size, &buf,
+				   crlf_warn, NULL)) {
 			size_t size = 0;
 			munmap(s->data, s->size);
 			s->should_munmap = 0;