diff: support bare repositories when reading gitattributes for diff algorithm

From: John Cai <[email protected]>

(a4cf900e diff: teach diff to read algorithm from diff driver, 2022-02-20) does not support bare repositories.

Since running diff
on bare repositories is often done on Git servers, it would be useful to allow bare repositories to also take advantage of setting the algorithm via the diff driver.

This patch series adds support for bare repositories for the feature added in [1]. When using a bare repository, by default we will look for gitattributes from HEAD. When the --attr-source option is passed, we will try to read gitattributes from the commit.

Since referring to in-tree attributes is often useful with any command, not limited to "diff", I wonder if it is feasible to add support for the --attr-source=<tree> option globally, instead of implementing such an option piecemeal. If your "git diff" in a bare repository starts honoring attributes recorded in HEAD, don't your users expect your "git log" and "git show" to also honor them?

Hi John,

Le 2023-03-13 à 21:53, John Cai via GitGitGadget a écrit :

Quoted 4 lines

This patch series adds support for bare repositories for the feature added in [1]. When using a bare repository, by default we will look for gitattributes from HEAD. When the --attr-source option is passed, we will try to read gitattributes from the commit.

When I read that I immediately thought of the config settings 'mailmap.file', 'mailmap.blob' which allow the same sort of thing, but for the mailmap.

For the sake of consistency of the whole system, maybe we would want to support 'attr.file' and 'attr.blob' ? In that case, maybe we don't need a new command line option at all...

Cheers,

Philippe.

Junio C Hamano <[email protected]> writes:

Quoted 7 lines

Since referring to in-tree attributes is often useful with any command, not limited to "diff", I wonder if it is feasible to add support for the --attr-source=<tree> option globally, instead of implementing such an option piecemeal. If your "git diff" in a bare repository starts honoring attributes recorded in HEAD, don't your users expect your "git log" and "git show" to also honor them?

Just for illustration, here is one way to do so.

The implementation goes in the opposite direction from the more recent trend, which is why I am not making it an official patch, but

with this you can do things like:

  $ git --attr-source=e83c5163 check-attr whitespace cache.h
  cache.h: whitespace: unspecified
  $ git --attr-source=e2f6331a142^ check-attr whitespace cache.h
  cache.h: whitespace: set
  $ git --attr-source=HEAD check-attr whitespace cache.h
  cache.h: whitespace: indent,trail,space

where e83c5163 is the very first version of Git from 2005 where .gitattributes did not exist, e2f6331a142^ is the last version before we set whitespace to indent,trail,space, and HEAD is a more recent version of our source tree.

In the following illustration patch, the attr-source tree object name is kept as a string as long as possible and at the very last minute when we call git_check_attr() for the first time we turn it into an object id. This is because at the very early stage when we parse the global option we may not even know where our repository is (hence do not have enough information to parse HEAD). We also figure out is_bare_repository() late in the process for the same reason.

 attr.c | 29 +++++++++++++++++++++++++++++
 attr.h |  6 ++++++
 git.c  |  3 +++
 3 files changed, 38 insertions(+)

attr.c +29 -0

index 1053dfcd4b..2fd6e0eab2 100644
@@ -1165,12 +1165,41 @@ static void collect_some_attrs(struct index_state *istate,
 	fill(path, pathlen, basename_offset, check->stack, check->all_attrs, rem);
 }
 
+static const char *default_attr_source_tree_object_name;
+
+void set_git_attr_source(const char *tree_object_name)
+{
+	default_attr_source_tree_object_name = xstrdup(tree_object_name);
+}
+
+
+static struct object_id *default_attr_source(void)
+{
+	static struct object_id attr_source;
+
+	if (is_null_oid(&attr_source)) {
+		if (!default_attr_source_tree_object_name &&
+		    is_bare_repository())
+			default_attr_source_tree_object_name = "HEAD";
+
+		if (default_attr_source_tree_object_name &&
+		    is_null_oid(&attr_source))
+			get_oid(default_attr_source_tree_object_name, &attr_source);
+	}
+	if (is_null_oid(&attr_source))
+		return NULL;
+	return &attr_source;
+}
+
 void git_check_attr(struct index_state *istate,
 		    const struct object_id *tree_oid, const char *path,
 		    struct attr_check *check)
 {
 	int i;
 
+	if (!tree_oid)
+		tree_oid = default_attr_source();
+
 	collect_some_attrs(istate, tree_oid, path, check);
 
 	for (i = 0; i < check->nr; i++) {

attr.h +6 -0

index 9884ea2bc6..a77e3713b2 100644
@@ -135,6 +135,12 @@ struct git_attr;
 struct all_attrs_item;
 struct attr_stack;
 
+/*
+ * The textual object name for the tree-ish used by git_check_attr()
+ * when NULL is given to tree_oid.
+ */
+void set_git_attr_source(const char *);
+
 /*
  * Given a string, return the gitattribute object that
  * corresponds to it.

git.c +3 -0

index 6171fd6769..21bddc5718 100644
@@ -4,6 +4,7 @@
 #include "help.h"
 #include "run-command.h"
 #include "alias.h"
+#include "attr.h"
 #include "shallow.h"
 
 #define RUN_SETUP		(1<<0)

@@ -307,6 +308,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			} else {
 				exit(list_cmds(cmd));
 			}
+		} else if (skip_prefix(cmd, "--attr-source=", &cmd)) {
+			set_git_attr_source(cmd);
 		} else {
 			fprintf(stderr, _("unknown option: %s\n"), cmd);
 			usage(git_usage_string);

Quoted 4 lines

Just for illustration, here is one way to do so.

The implementation goes in the opposite direction from the more recent trend, which is why I am not making it an official patch, but

Could you explain why this goes against the "more recent trend" for my understanding?

Quoted 8 lines

with this you can do things like:

  $ git --attr-source=e83c5163 check-attr whitespace cache.h
  cache.h: whitespace: unspecified
  $ git --attr-source=e2f6331a142^ check-attr whitespace cache.h
  cache.h: whitespace: set
  $ git --attr-source=HEAD check-attr whitespace cache.h
  cache.h: whitespace: indent,trail,space

I like the idea of an option that is global. For git-check-attr however, we

I wasn't aware of those config options. Indeed that's a good option! My only concern with that is that there is already some precedence for passing a <tree-ish> as a source for attributes in [1], so I thought adding a command line option would be somewhat consistent.

But I can also see the benefit of using a config value since there is also precedence because of mailmap.file and mailmap.blob. Not sure what others think, but this may be the less invasive way to go.

Quoted 8 lines · John Cai

I wasn't aware of those config options. Indeed that's a good option! My only concern with that is that there is already some precedence for passing a <tree-ish> as a source for attributes in [1], so I thought adding a command line option would be somewhat consistent.

But I can also see the benefit of using a config value since there is also precedence because of mailmap.file and mailmap.blob. Not sure what others think, but this may be the less invasive way to go.

I actually hate these one-off variables, and I wish we didn't do mailmap.file or mailmap.blob at all. Instead we could have taught the machinery to read from $GIT_DIR/info/mailmap just like the exclude and the attribute machinery already knows to read excludea and attributes files in the directory.

As your "per filetype (determined by the attribute) diff algorithm in a bare repository" feature already depends on being able to use config (as the look-up is "attributes determines the diff filetype name, and then diff.<filetype>.algo is looked up in the config") to configure, it does not sound too bad to add the attribute info in the $GIT_DIR/info/attributes file in your bare repository (and you'd set the algorithm in $GIT_DIR/config file there), and it would just work without any new "read from HEAD" feature, I would presume?

If you have a static list of attributes, that is OK (though you are presumably better off with /etc/gitattributes or similar that covers all repos).
...
but still tell users that "json" is a well-known name, and if they want to get the same treatment for an arbitrary file "foo" that they would get for "foo.json", they have to add attributes mapping it, like:

foo diff=json

inside their repo.

Quoted 5 lines · John Cai

Quoted 4 lines

Just for illustration, here is one way to do so.

The implementation goes in the opposite direction from the more recent trend, which is why I am not making it an official patch, but

Quoted 2 lines

Could you explain why this goes against the "more recent trend" for my understanding?

The illustration uses a global state.

The recent trend is to reduce reliance on global states and use the repository object and others that hold such state through the callchain.

But a new global variable that holds the fallback tree-ish object name was a so convenient way to illustrate the core of the idea, without having to change many callchains.

Quoted 10 lines

Quoted 8 lines

with this you can do things like:

  $ git --attr-source=e83c5163 check-attr whitespace cache.h
  cache.h: whitespace: unspecified
  $ git --attr-source=e2f6331a142^ check-attr whitespace cache.h
  cache.h: whitespace: set
  $ git --attr-source=HEAD check-attr whitespace cache.h
  cache.h: whitespace: indent,trail,space

I like the idea of an option that is global. For git-check-attr however, we

I guess I shouldn't have used check-attr to avoid confusion.

The point is that the internal mechanisms introduced by 47cfc9bd (attr: add flag --source to work with tree-ish, 2023-01-14), which taught check-attr the --source option and is reused by this illustration patch, was a good idea, but its UI was a mistake. We do not need per-command --source option the commit adds if we did the global option from day one. Yes, I think we can deprecate the "--source" option from there, if we all prefer the global option avenue. I _think_ git_all_attrs() needs to be told about the default attr-source trick (which I didn't touch in my illustration patch) before it happens, though.

If you used the mechanism in the illustration patch I gave you, and adjusted the test part of your patch to match (i.e. "diff" does not learn "--attr-source" option, but "git --attr-source=... diff" is how you make it read attributes from a tree-ish), would the result work well, or do we need more work to make it usable? How well do other commands (e.g. "git show") work in the same test repository you created in your version?

Thanks.

Ah I see--in that case, what would be a good object to put this state into? Mabe repo_settings?

Quoted 2 lines · John Cai

Ah I see--in that case, what would be a good object to put this state into? Mabe repo_settings?

I personally think a global is good enough for a case like this. It is not like the code in the attribute subsystem is structured to work in multiple repositories at the same time in the first place, so in repo_settings, the_repository, or elsewhere is just as good as having it in a plain old file-scope static, and even after moving it into the_repository or something, the access will initially be done by referring to the_repository global (which may not even exist by the time "git --attr-source=<tree>" gets parsed), and not by plumbing a "struct repository *" parameter through the callchain.

Another thing to note is that there needs a mechanism to convey the tree object used to read the attributes from down to subprocesses, e.g. exporting the GIT_ATTR_SOURCE environment variable and make Git behave as if it saw the "git --attr-source=<tree>" option when such an environment variable exists, or something. Otherwise, the custom attribute source would only take effect inside built-in commands.

In any case, here is what I have now, stealing some tests from your patch. I do not think I'll be working on it further at least for now, so feel free to run with it. I am not adding the "in a bare repository, always read from HEAD unless told otherwise", as I do not see a good way to countermand it from a command line.

----- >8 ----- cut here ----- >8 ----- cut here ----- >8 -----
Subject: [PATCH] attr: teach "--attr-source=<tree>" global option to "git"

Earlier, 47cfc9bd (attr: add flag --source to work with tree-ish, 2023-01-14) taught "git check-attr" the "--source=<tree>" option to allow it to read attribute files from a tree-ish, but did so only for the command. Just like "check-attr" users wanted a way to use attributes from a tree-ish and not from the working tree files, users of other commands (like "git diff") would benefit from the same.

Undo most of the UI change the commit made, while keeping the internal logic to read attributes from a given tree-ish. Expose the internal logic via a new "--attr-source=<tree>" command line option given to "git", so that it can be used with any git command that runs internally.

The tests were stolen and adjusted from John Cai's effort where only "git diff" learned the "--attr-source" option to read from a tree-ish.

Signed-off-by Junio C Hamano <[email protected]>

---
 archive.c                 |  2 +-
 attr.c                    | 34 ++++++++++++++++++++++++++++++++--
 attr.h                    | 13 +++++++++----
 builtin/check-attr.c      | 17 ++++++++---------
 builtin/pack-objects.c    |  2 +-
 convert.c                 |  2 +-
 git.c                     |  3 +++
 ll-merge.c                |  4 ++--
 pathspec.c                |  2 +-
 t/lib-diff-alternative.sh | 31 ++++++++++++++++++++++++++-----
 t/t0003-attributes.sh     |  7 ++++++-
 t/t4018-diff-funcname.sh  | 19 +++++++++++++++++++
 userdiff.c                |  2 +-
 ws.c                      |  2 +-
 14 files changed, 111 insertions(+), 29 deletions(-)

archive.c +1 -1

index 9aeaf2bd87..385aa5f248 100644
@@ -120,7 +120,7 @@ static const struct attr_check *get_archive_attrs(struct index_state *istate,
 	static struct attr_check *check;
 	if (!check)
 		check = attr_check_initl("export-ignore", "export-subst", NULL);
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 	return check;
 }
 

attr.c +32 -2

index 1053dfcd4b..d34c7e9d54 100644
@@ -1165,11 +1165,40 @@ static void collect_some_attrs(struct index_state *istate,
 	fill(path, pathlen, basename_offset, check->stack, check->all_attrs, rem);
 }
 
+static const char *default_attr_source_tree_object_name;
+
+void set_git_attr_source(const char *tree_object_name)
+{
+	default_attr_source_tree_object_name = xstrdup(tree_object_name);
+}
+
+
+static void compute_default_attr_source(struct object_id *attr_source)
+{
+	if (!default_attr_source_tree_object_name || !is_null_oid(attr_source))
+		return;
+
+	if (get_oid_treeish(default_attr_source_tree_object_name, attr_source))
+		die(_("bad --attr-source object"));
+}
+
+static struct object_id *default_attr_source(void)
+{
+	static struct object_id attr_source;
+
+	if (is_null_oid(&attr_source))
+		compute_default_attr_source(&attr_source);
+	if (is_null_oid(&attr_source))
+		return NULL;
+	return &attr_source;
+}
+
 void git_check_attr(struct index_state *istate,
-		    const struct object_id *tree_oid, const char *path,
+		    const char *path,
 		    struct attr_check *check)
 {
 	int i;
+	const struct object_id *tree_oid = default_attr_source();
 
 	collect_some_attrs(istate, tree_oid, path, check);
 

@@ -1182,10 +1211,11 @@ void git_check_attr(struct index_state *istate,
 	}
 }
 
-void git_all_attrs(struct index_state *istate, const struct object_id *tree_oid,
+void git_all_attrs(struct index_state *istate,
 		   const char *path, struct attr_check *check)
 {
 	int i;
+	const struct object_id *tree_oid = default_attr_source();
 
 	attr_check_reset(check);
 	collect_some_attrs(istate, tree_oid, path, check);

attr.h +9 -4

index 9884ea2bc6..676bd17ce2 100644
@@ -45,7 +45,7 @@
  * const char *path;
  *
  * setup_check();
- * git_check_attr(&the_index, tree_oid, path, check);
+ * git_check_attr(&the_index, path, check);
  * ------------
  *
  * - Act on `.value` member of the result, left in `check->items[]`:

@@ -120,7 +120,6 @@
 #define ATTR_MAX_FILE_SIZE (100 * 1024 * 1024)
 
 struct index_state;
-struct object_id;
 
 /**
  * An attribute is an opaque object that is identified by its name. Pass the

@@ -135,6 +134,12 @@ struct git_attr;
 struct all_attrs_item;
 struct attr_stack;
 
+/*
+ * The textual object name for the tree-ish used by git_check_attr()
+ * to read attributes from (instead of from the working tree).
+ */
+void set_git_attr_source(const char *);
+
 /*
  * Given a string, return the gitattribute object that
  * corresponds to it.

@@ -203,14 +208,14 @@ void attr_check_free(struct attr_check *check);
 const char *git_attr_name(const struct git_attr *);
 
 void git_check_attr(struct index_state *istate,
-		    const struct object_id *tree_oid, const char *path,
+		    const char *path,
 		    struct attr_check *check);
 
 /*
  * Retrieve all attributes that apply to the specified path.
  * check holds the attributes and their values.
  */
-void git_all_attrs(struct index_state *istate, const struct object_id *tree_oid,
+void git_all_attrs(struct index_state *istate,
 		   const char *path, struct attr_check *check);
 
 enum git_attr_direction {

builtin/check-attr.c +8 -9

index d7a40e674c..1a7929c980 100644
@@ -58,7 +58,7 @@ static void output_attr(struct attr_check *check, const char *file)
 }
 
 static void check_attr(const char *prefix, struct attr_check *check,
-		       const struct object_id *tree_oid, int collect_all,
+		       int collect_all,
 		       const char *file)
 
 {

@@ -66,9 +66,9 @@ static void check_attr(const char *prefix, struct attr_check *check,
 		prefix_path(prefix, prefix ? strlen(prefix) : 0, file);
 
 	if (collect_all) {
-		git_all_attrs(&the_index, tree_oid, full_path, check);
+		git_all_attrs(&the_index, full_path, check);
 	} else {
-		git_check_attr(&the_index, tree_oid, full_path, check);
+		git_check_attr(&the_index, full_path, check);
 	}
 	output_attr(check, file);
 

@@ -76,7 +76,7 @@ static void check_attr(const char *prefix, struct attr_check *check,
 }
 
 static void check_attr_stdin_paths(const char *prefix, struct attr_check *check,
-				   const struct object_id *tree_oid, int collect_all)
+				   int collect_all)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf unquoted = STRBUF_INIT;

@@ -90,7 +90,7 @@ static void check_attr_stdin_paths(const char *prefix, struct attr_check *check,
 				die("line is badly quoted");
 			strbuf_swap(&buf, &unquoted);
 		}
-		check_attr(prefix, check, tree_oid, collect_all, buf.buf);
+		check_attr(prefix, check, collect_all, buf.buf);
 		maybe_flush_or_die(stdout, "attribute to stdout");
 	}
 	strbuf_release(&buf);

@@ -106,7 +106,6 @@ static NORETURN void error_with_usage(const char *msg)
 int cmd_check_attr(int argc, const char **argv, const char *prefix)
 {
 	struct attr_check *check;
-	struct object_id *tree_oid = NULL;
 	struct object_id initialized_oid;
 	int cnt, i, doubledash, filei;
 

@@ -182,14 +181,14 @@ int cmd_check_attr(int argc, const char **argv, const char *prefix)
 	if (source) {
 		if (repo_get_oid_tree(the_repository, source, &initialized_oid))
 			die("%s: not a valid tree-ish source", source);
-		tree_oid = &initialized_oid;
+		set_git_attr_source(source);
 	}
 
 	if (stdin_paths)
-		check_attr_stdin_paths(prefix, check, tree_oid, all_attrs);
+		check_attr_stdin_paths(prefix, check, all_attrs);
 	else {
 		for (i = filei; i < argc; i++)
-			check_attr(prefix, check, tree_oid, all_attrs, argv[i]);
+			check_attr(prefix, check, all_attrs, argv[i]);
 		maybe_flush_or_die(stdout, "attribute to stdout");
 	}
 

builtin/pack-objects.c +1 -1

index 74a167a180..d561541b8c 100644
@@ -1320,7 +1320,7 @@ static int no_try_delta(const char *path)
 
 	if (!check)
 		check = attr_check_initl("delta", NULL);
-	git_check_attr(the_repository->index, NULL, path, check);
+	git_check_attr(the_repository->index, path, check);
 	if (ATTR_FALSE(check->items[0].value))
 		return 1;
 	return 0;

convert.c +1 -1

index a54d1690c0..9b67649032 100644
@@ -1308,7 +1308,7 @@ void convert_attrs(struct index_state *istate,
 		git_config(read_convert_config, NULL);
 	}
 
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 	ccheck = check->items;
 	ca->crlf_action = git_path_check_crlf(ccheck + 4);
 	if (ca->crlf_action == CRLF_UNDEFINED)

git.c +3 -0

index 6171fd6769..21bddc5718 100644
@@ -4,6 +4,7 @@
 #include "help.h"
 #include "run-command.h"
 #include "alias.h"
+#include "attr.h"
 #include "shallow.h"
 
 #define RUN_SETUP		(1<<0)

@@ -307,6 +308,8 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			} else {
 				exit(list_cmds(cmd));
 			}
+		} else if (skip_prefix(cmd, "--attr-source=", &cmd)) {
+			set_git_attr_source(cmd);
 		} else {
 			fprintf(stderr, _("unknown option: %s\n"), cmd);
 			usage(git_usage_string);

ll-merge.c +2 -2

index 130d26501c..22a603e8af 100644
@@ -391,7 +391,7 @@ enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 		normalize_file(theirs, path, istate);
 	}
 
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 	ll_driver_name = check->items[0].value;
 	if (check->items[1].value) {
 		marker_size = atoi(check->items[1].value);

@@ -419,7 +419,7 @@ int ll_merge_marker_size(struct index_state *istate, const char *path)
 
 	if (!check)
 		check = attr_check_initl("conflict-marker-size", NULL);
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 	if (check->items[0].value) {
 		marker_size = atoi(check->items[0].value);
 		if (marker_size <= 0)

pathspec.c +1 -1

index ab70fcbe61..74e02c75fc 100644
@@ -730,7 +730,7 @@ int match_pathspec_attrs(struct index_state *istate,
 	if (name[namelen])
 		name = to_free = xmemdupz(name, namelen);
 
-	git_check_attr(istate, NULL, name, item->attr_check);
+	git_check_attr(istate, name, item->attr_check);
 
 	free(to_free);
 

t/lib-diff-alternative.sh +26 -5

index a8f5d3274a..02381eb7f1 100644
@@ -112,15 +112,36 @@ EOF
 
 	STRATEGY=$1
 
-	test_expect_success "$STRATEGY diff from attributes" '
+	test_expect_success "setup attributes files for tests with $STRATEGY" '
+		git checkout -b master &&
 		echo "file* diff=driver" >.gitattributes &&
-		git config diff.driver.algorithm "$STRATEGY" &&
-		test_must_fail git diff --no-index file1 file2 > output &&
-		cat expect &&
-		cat output &&
+		git add file1 file2 .gitattributes &&
+		git commit -m "adding files" &&
+		git checkout -b branchA &&
+		echo "file* diff=driverA" >.gitattributes &&
+		git add .gitattributes &&
+		git commit -m "adding driverA as diff driver" &&
+		git checkout master &&
+		git clone --bare --no-local . bare.git
+	'
+
+	test_expect_success "$STRATEGY diff from attributes" '
+		test_must_fail git -c diff.driver.algorithm=$STRATEGY diff --no-index file1 file2 > output &&
 		test_cmp expect output
 	'
 
+	test_expect_success "diff from attributes with bare repo when branch different than HEAD" '
+		git -C bare.git --attr-source=branchA -c diff.driver.algorithm=myers \
+			-c diff.driverA.algorithm=$STRATEGY \
+			diff HEAD:file1 HEAD:file2 >output &&
+		test_cmp expect output
+	'
+
+	test_expect_success "diff from attributes with bare repo with invalid source" '
+		test_must_fail git -C bare.git --attr-source=invalid-branch diff \
+			HEAD:file1 HEAD:file2
+	'
+
 	test_expect_success "$STRATEGY diff from attributes has valid diffstat" '
 		echo "file* diff=driver" >.gitattributes &&
 		git config diff.driver.algorithm "$STRATEGY" &&

t/t0003-attributes.sh +6 -1

index 89b306cb11..73db37a7f3 100755
@@ -30,8 +30,13 @@ attr_check_quote () {
 attr_check_source () {
 	path="$1" expect="$2" source="$3" git_opts="$4" &&
 
-	git $git_opts check-attr --source $source test -- "$path" >actual 2>err &&
 	echo "$path: test: $expect" >expect &&
+
+	git $git_opts check-attr --source $source test -- "$path" >actual 2>err &&
+	test_cmp expect actual &&
+	test_must_be_empty err &&
+
+	git $git_opts --attr-source="$source" check-attr test -- "$path" >actual 2>err &&
 	test_cmp expect actual &&
 	test_must_be_empty err
 }

t/t4018-diff-funcname.sh +19 -0

index 42a2b9a13b..c8d555771d 100755
@@ -63,6 +63,25 @@ do
 		test_i18ngrep ! fatal msg &&
 		test_i18ngrep ! error msg
 	'
+
+	test_expect_success "builtin $p pattern compiles on bare repo with --attr-source" '
+		test_when_finished "rm -rf bare.git" &&
+		git checkout -B master &&
+		git add . &&
+		echo "*.java diff=notexist" >.gitattributes &&
+		git add .gitattributes &&
+		git commit -am "changing gitattributes" &&
+		git checkout -B branchA &&
+		echo "*.java diff=$p" >.gitattributes &&
+		git add .gitattributes &&
+		git commit -am "changing gitattributes" &&
+		git clone --bare --no-local . bare.git &&
+		git -C bare.git symbolic-ref HEAD refs/heads/master &&
+		test_expect_code 1 git -C bare.git --attr-source=branchA \
+			diff --exit-code HEAD:A.java HEAD:B.java 2>msg &&
+		test_i18ngrep ! fatal msg &&
+		test_i18ngrep ! error msg
+	'
 done
 
 test_expect_success 'last regexp must not be negated' '

userdiff.c +1 -1

index 58a3d59ef8..156660eaca 100644
@@ -415,7 +415,7 @@ struct userdiff_driver *userdiff_find_by_path(struct index_state *istate,
 		check = attr_check_initl("diff", NULL);
 	if (!path)
 		return NULL;
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 
 	if (ATTR_TRUE(check->items[0].value))
 		return &driver_true;

ws.c +1 -1

index da3d0e28cb..903bfcd53e 100644
@@ -79,7 +79,7 @@ unsigned whitespace_rule(struct index_state *istate, const char *pathname)
 	if (!attr_whitespace_rule)
 		attr_whitespace_rule = attr_check_initl("whitespace", NULL);
 
-	git_check_attr(istate, NULL, pathname, attr_whitespace_rule);
+	git_check_attr(istate, pathname, attr_whitespace_rule);
 	value = attr_whitespace_rule->items[0].value;
 	if (ATTR_TRUE(value)) {
 		/* true (whitespace) */