Attr fixes

This fixes a few issues surrounding .gitattributes files and usage of the merge machinery outside of "git merge". All were issues I found and fixed while working on merge-ort.

Changes since v1:

* Made the fixes suggested by Eric and Junio
* Just ripped out the test in patch 2 that was testing undefined behavior (especially since it was a test_expect_failure, and clearly was testing multiple things wrong), as suggested by Junio.

Elijah Newren (4):
t6038: make tests fail for the right reason
t6038: remove problematic test
merge: make merge.renormalize work for all uses of merge machinery
checkout: support renormalization with checkout -m <paths>

 builtin/checkout.c         | 18 ++++++------------
 builtin/merge.c            |  4 ----
 merge-recursive.c          |  3 +++
 t/t6038-merge-text-auto.sh | 26 ++++++--------------------
 4 files changed, 15 insertions(+), 36 deletions(-)

base-commit: 47ae905ffb98cc4d4fd90083da6bc8dab55d9ecc
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-825%2Fnewren%2Fattr-fixes-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-825/newren/attr-fixes-v2
Pull-Request: https://github.com/git/git/pull/825

Range-diff vs v1:

1: 3619118175 ! 1: 21033c4c14 t6038: make tests fail for the right reason
@@ Commit message
t6038 had a pair of tests that were expected to fail, but weren't failing for the expected reason. Both were meant to do a merge that could be done cleanly after renormalization, but were supposed to fail
- for lack of renormalization. Unfortunately, both tests has staged
+ for lack of renormalization. Unfortunately, both tests had staged
changes, and checkout -m would abort due to the presence of those staged changes before even attempting a merge.

2: 83a50f7e0b ! 2: 305fe534c5 t6038: fix test with obviously incorrect expectations
@@ Metadata
Author: Elijah Newren <[email protected]>

## Commit message ##
- t6038: fix test with obviously incorrect expectations
+ t6038: remove problematic test

- t6038.11, 'cherry-pick patch from after text=auto' was set up so that on
- a branch with no .gitattributes file, you cherry-picked a patch from a
- branch that had a .gitattributes file (containing '* text=auto').
- Further, the two branches had a file which differed only in line
- endings. In this situation, correct behavior is not well defined:
- should the .gitattributes file affect the merge or not?
+ t6038.11, 'cherry-pick patch from after text=auto' was a test of
+ undefined behavior. To make matters worse, while there are a couple
+ possible correct answers, this test was coded to only check for an
+ obviously incorrect answer. And the final cherry on top is that the
+ test is marked test_expect_failure, meaning it can't provide much value,
+ other than possibly confusing future folks who come along and try to
+ work on attributes and look at existing tests. Because of all these
+ problems, just remove the test.
+
+ But for any future code spelunkers, here's my understanding of the two
+ possible correct answers:
+
+ This test was set up so that on a branch with no .gitattributes file,
+ you cherry-picked a patch from a branch that had a .gitattributes file
+ (containing '* text=auto'). Further, the two branches had a file which
+ differed only in line endings. In this situation, correct behavior is
+ not well defined: should the .gitattributes file affect the merge or
+ not?

If the .gitattributes file on the other branch should not affect the merge, then we would have a content conflict with all three stages different (the merge base didn't match either side).

If the .gitattributes file from the other branch should affect the
- merge, then we would expect the line endings to be normalized to LF so
- that the versions from both sides match, and then the cherry-pick has no
- conflicts and can succeed. After the cherry-pick, the line endings in
- the file will change from CRLF to LF.
-
- This test had an expectation that the line endings would remain CRLF.
- Further, it expected an error message that was built assuming
- cherry-pick was the old scripted version, because cherry-pick no longer
- uses the error message that was encoded in this test. So, although I
- don't know what correct behavior for this test is, I know that this test
- was not testing for it.
-
- Since I have no idea which of the two cases above provides correct
- behavior, let's just assume for now it's the case where we assume that
- .gitattributes affects the merge and update it accordingly.
+ merge, then we would expect the line endings to be normalized to LF for
+ the version to be recorded in the repository. This would mean that when
+ doing a three-way content merge on the file that differed in line
+ endings, that the three-way content merge would see that the versions on
+ both sides matched and so the cherry-pick has no conflicts and can
+ succeed. The line endings in the file as recorded in the repository
+ will change from CRLF to LF. The version checked out in the working
+ copy will depend on the platform (since there's no eol attribute defined
+ for the file).
+
+ Also, as a final side note, this test expected an error message that was
+ built assuming cherry-pick was the old scripted version, because
+ cherry-pick no longer uses the error message that was encoded in this
+ test. So it was wrong for yet another reason.
+
+ Given that the handling of .gitattributes is not well defined and this
+ test was obviously broken and could do nothing but confuse future
+ readers, just remove it.

## t/t6038-merge-text-auto.sh ##
@@ t/t6038-merge-text-auto.sh: test_expect_failure 'checkout -m addition of text=auto' '
+ git diff --no-index --ignore-cr-at-eol expected file
'

- test_expect_failure 'cherry-pick patch from after text=auto was added' ' +-test_expect_failure 'cherry-pick patch from after text=auto was added' '
- append_cr <<-\EOF >expected &&
-+ cat <<-\EOF >expected &&
- first line
- same line
- EOF
-@@ t/t6038-merge-text-auto.sh: test_expect_failure 'cherry-pick patch from after text=auto was added' '
- git config merge.renormalize true &&
- git rm -fr . &&
- git reset --hard b &&
+- first line
+- same line
+- EOF
+-
+- git config merge.renormalize true &&
+- git rm -fr . &&
+- git reset --hard b &&
- test_must_fail git cherry-pick a >err 2>&1 &&
- grep "[Nn]othing added" err &&
- compare_files expected file
-+ git cherry-pick a &&
-+ git cat-file -p HEAD:file >actual &&
-+ compare_files expected actual
- '
-
+-'
+-
test_expect_success 'Test delete/normalize conflict' '
+ git checkout -f side &&
+ git rm -fr . &&
3: 08c8080b31 ! 3: 379a87ea82 merge: make merge.renormalize work for all uses of merge machinery

     @@ builtin/merge.c: static const char **xopts;
       static const char *branch;
       static char *branch_mergeoptions;
      -static int option_renormalize;
     -+static int option_renormalize = -1;
       static int verbosity;
       static int allow_rerere_auto;
       static int abort_current_merge;
     @@ builtin/merge.c: static int try_merge_strategy(const char *strategy, struct comm
       			o.subtree_shift = "";
       
      -		o.renormalize = option_renormalize;
     -+		if (option_renormalize != -1)
     -+			o.renormalize = option_renormalize;
       		o.show_rename_progress =
       			show_progress == -1 ? isatty(2) : show_progress;

4: fcc7ea3add = 4: 36e08a75a3 checkout: support renormalization with checkout -m <paths>

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