Re: [PATCH 4/4] diffcore-delta.c: Ignore CR in CRLF for text files

しらいしななこ  [off-list ref] writes:

Quoting Junio C Hamano [off-list ref]:

quoted

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

I tried this test but it does not give R100.  The new file is unchanged except for
LF -> CRLF.  Could you explain why?

Heh, I hate when people nitpick me ;-)

The similarity code counts "bytes copied from the source
material to the destination" and "bytes added to the source to
create the destination".

Rename detection uses only the former value.  The amount of data
copied from the source is divided by the larger of the size of
source or destination.

In the case of our test script, the source material is about 560
bytes, while the destination material is about 590 bytes, after 
adding CR to the end of every line.  We find that 560 bytes have
been copied from the source material, and floor(560 * 100 / 590)
is 94%, which is what you would see as the result.

We could adjust max_size variable inside diffcore_count_changes,
but I am not sure if it is worth the trouble.