When calling "git diff -- a b", as opposed to "git diff a b" without "--",
do not default to --no-index inside a git repository.
For example,
git mv a b && git diff -- a b
used to have an unexpected result.
Noticed by Catalin Marinas, diagnosed by Linus.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
On Fri, 23 May 2008, Junio C Hamano wrote:
> Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes:
>
> > ... So I would suggest that we make it *much* harder to
> > trigger the "make it act like a traditional 'diff'" thing.
> >
> > I would suggest that we *not* invoce the traditional 'diff'
> > behaviour when:
> >
> > - we're called as "git-diff-files". That's clearly a git
> > thing. Don't try to make it act like an external non-git diff.
> > Only do the special case for plain "git diff" itself.
I am not so sure about that.
> > - even for plain "git diff", make it much harder to trigger
> > non-git behaviour. Don't do it if the files don't exist.
> > Don't do it if there is '--' there.
> >
> > In fact, maybe we should remove that thing entirely, or
> > *require* a flag to enable it (at least if we're in a git
> > directory). It's a cute hack, but when the cute hack actually
> > makes it impossible to do certain real git operations, it's a
> > cute hack that is detrimental.
>
> Very well said. I've always wanted to rip that hack out of the
> normal "git diff with two pathspec parameters" codepath.
Yes, I see how that cute hack does the wrong thing here.
However, it is pretty convenient to be able to say "git diff a b"
and have it fall back to --no-index if either a or b is not in the
index. Most of the time, I would actually expect it to be the
right thing, too.
Hey, but if you disagree, just rip it out. Actually, I did that
already, and will reply with that alternative patch.
diff-lib.c | 4 ++--
t/t4002-diff-basic.sh | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/diff-lib.c b/diff-lib.c
index fe2ccec..b1daad6 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -257,8 +257,8 @@ int setup_diff_no_index(struct rev_info *revs,
if (argv[i][0] != '-' || argv[i][1] == '\0')
break;
else if (!strcmp(argv[i], "--")) {
- i++;
- break;
+ revs->max_count = -2;
+ return -1;
} else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
i = argc - 3;
DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
diff --git a/t/t4002-diff-basic.sh b/t/t4002-diff-basic.sh
index a4cfde6..678c4a5 100755
--- a/t/t4002-diff-basic.sh
+++ b/t/t4002-diff-basic.sh
@@ -244,4 +244,35 @@ test_expect_success \
git diff-tree -r -R $tree_A $tree_B >.test-b &&
cmp -s .test-a .test-b'
+cat > expect << EOF
+diff --git a/AA b/AA
+index ccba72a..6aa2b53 100644
+--- a/AA
++++ b/AA
+@@ -1 +1 @@
+-This is added AA in the branch A.
++This is added AA in the branch B.
+EOF
+
+test_expect_success '"diff -- AA DM" does not imply --no-index' '
+
+ git diff -- AA DM > output &&
+ cmp -s output expect
+
+'
+
+cat > expect << EOF
+diff --git a/AA b/DM
+index 6aa2b53..3c4d8de 100644
+--- a/AA
++++ b/DM
+@@ -1 +1 @@
+-This is added AA in the branch B.
++This is modified DM in the branch B.
+EOF
+
+test_expect_success '"diff AA DM" implies --no-index' '
+
+'
+
test_done
--
1.5.5.1.553.ga1dd7.dirty
--
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