[PATCH v2 10/10] cat-file: improve --(textconv|filters) disambiguation

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Improve the errors emitted when an invalid <object> and/or <path> is
provided with either the --path option, or as an argument. We now use
the same logic in get_oid_with_context_1() that "git show" et al use.

To replace the "cat-file" use-case we need to introduce a new
"GET_OID_REQUIRE_PATH" flag, otherwise it would exit early as soon as
a valid "HEAD" was resolved, but in the "cat-file" case being changed
we always need a valid revision and path.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/cat-file.c           | 15 +++++----------
 cache.h                      |  1 +
 object-name.c                |  6 +++++-
 t/t8007-cat-file-textconv.sh |  6 +++---
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 1d7f79184f0..b76f2a00046 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -73,14 +73,16 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	struct object_info oi = OBJECT_INFO_INIT;
 	struct strbuf sb = STRBUF_INIT;
 	unsigned flags = OBJECT_INFO_LOOKUP_REPLACE;
+	unsigned get_oid_flags = GET_OID_RECORD_PATH | GET_OID_ONLY_TO_DIE;
 	const char *path = force_path;
+	if (!path && (opt == 'w' || opt == 'c'))
+		get_oid_flags |= GET_OID_REQUIRE_PATH;
 
 	if (unknown_type)
 		flags |= OBJECT_INFO_ALLOW_UNKNOWN_TYPE;
 
-	if (get_oid_with_context(the_repository, obj_name,
-				 GET_OID_RECORD_PATH,
-				 &oid, &obj_context))
+	if (get_oid_with_context(the_repository, obj_name, get_oid_flags, &oid,
+				 &obj_context))
 		die("Not a valid object name %s", obj_name);
 
 	if (!path)
@@ -112,9 +114,6 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		return !has_object_file(&oid);
 
 	case 'w':
-		if (!path)
-			die("git cat-file --filters %s: <object> must be "
-			    "<sha1:path>", obj_name);
 
 		if (filter_object(path, obj_context.mode,
 				  &oid, &buf, &size))
@@ -122,10 +121,6 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		break;
 
 	case 'c':
-		if (!path)
-			die("git cat-file --textconv %s: <object> must be <sha1:path>",
-			    obj_name);
-
 		if (textconv_object(the_repository, path, obj_context.mode,
 				    &oid, 1, &buf, &size))
 			break;
diff --git a/cache.h b/cache.h
index eba12487b99..788127a9869 100644
--- a/cache.h
+++ b/cache.h
@@ -1366,6 +1366,7 @@ struct object_context {
 #define GET_OID_FOLLOW_SYMLINKS 0100
 #define GET_OID_RECORD_PATH     0200
 #define GET_OID_ONLY_TO_DIE    04000
+#define GET_OID_REQUIRE_PATH  010000
 
 #define GET_OID_DISAMBIGUATORS \
 	(GET_OID_COMMIT | GET_OID_COMMITTISH | \
diff --git a/object-name.c b/object-name.c
index d44a8f3a7ca..e94ced3f170 100644
--- a/object-name.c
+++ b/object-name.c
@@ -1799,8 +1799,12 @@ static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 	oc->mode = S_IFINVALID;
 	strbuf_init(&oc->symlink_path, 0);
 	ret = get_oid_1(repo, name, namelen, oid, flags);
-	if (!ret)
+	if (!ret) {
+		if (flags & GET_OID_REQUIRE_PATH)
+			die(_("<object>:<path> required, only <object> '%s' given"), name);
 		return ret;
+	}
+
 	/*
 	 * tree:path --> object name of path in tree
 	 * :path -> object name of absolute path in index
diff --git a/t/t8007-cat-file-textconv.sh b/t/t8007-cat-file-textconv.sh
index 45471cefe73..0b79750cf1e 100755
--- a/t/t8007-cat-file-textconv.sh
+++ b/t/t8007-cat-file-textconv.sh
@@ -27,19 +27,19 @@ test_expect_success 'usage' '
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	fatal: Not a valid object name HEAD2:two.bin
+	fatal: invalid object name '\''HEAD2'\''.
 	EOF
 	test_must_fail git cat-file --textconv HEAD2:two.bin 2>actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	fatal: git cat-file --textconv HEAD: <object> must be <sha1:path>
+	fatal: <object>:<path> required, only <object> '\''HEAD'\'' given
 	EOF
 	test_must_fail git cat-file --textconv HEAD 2>actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	fatal: Not a valid object name HEAD:two.bin
+	fatal: path '\''two.bin'\'' does not exist in '\''HEAD'\''
 	EOF
 	test_must_fail git cat-file --textconv HEAD:two.bin 2>actual &&
 	test_cmp expect actual
-- 
2.34.0.rc2.795.g926201d1cc8