Complete the <rev>^{<type>} family of object descriptors by having
<rev>^{tag} dereference <rev> until a tag object is found (or fail if
unable).
At first glance this may not seem very useful, as commits, trees, and
blobs cannot be peeled to a tag, and a tag would just peel to itself.
However, this can be used to ensure that <rev> names a tag object:
$ git rev-parse --verify v1.8.4^{tag}
04f013dc38d7512eadb915eba22efc414f18b869
$ git rev-parse --verify master^{tag}
error: master^{tag}: expected tag type, but the object dereferences to tree type
fatal: Needed a single revision
Users can already ensure that <rev> is a tag object by checking the
output of 'git cat-file -t <rev>', but:
* users may expect <rev>^{tag} to exist given that <rev>^{commit},
<rev>^{tree}, and <rev>^{blob} all exist
* this syntax is more convenient/natural in some circumstances
Signed-off-by: Richard Hansen <rhansen@xxxxxxx>
---
Changes since v2 (2013-09-02, see
<http://thread.gmane.org/gmane.comp.version-control.git/233598>):
* add a test case (hopefully I didn't go overboard)
* explain in the commit message why we might want <rev>^{tag} when
it's already possible to parse the output of 'git cat-file -t
<rev>'
Documentation/revisions.txt | 3 +++
sha1_name.c | 2 ++
t/t1511-rev-parse-caret.sh | 29 ++++++++++++++++++++++++++++-
3 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index d477b3f..b3322ad 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -121,6 +121,9 @@ some output processing may assume ref names in UTF-8.
object that exists, without requiring 'rev' to be a tag, and
without dereferencing 'rev'; because a tag is already an object,
it does not have to be dereferenced even once to get to an object.
++
+'rev{caret}\{tag\}' can be used to ensure that 'rev' identifies an
+existing tag object.
'<rev>{caret}\{\}', e.g. 'v0.99.8{caret}\{\}'::
A suffix '{caret}' followed by an empty brace pair
diff --git a/sha1_name.c b/sha1_name.c
index 65ad066..6dc496d 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -679,6 +679,8 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
sp++; /* beginning of type name, or closing brace for empty */
if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
expected_type = OBJ_COMMIT;
+ else if (!strncmp(tag_type, sp, 3) && sp[3] == '}')
+ expected_type = OBJ_TAG;
else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
expected_type = OBJ_TREE;
else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
diff --git a/t/t1511-rev-parse-caret.sh b/t/t1511-rev-parse-caret.sh
index eaefc77..5771cbd 100755
--- a/t/t1511-rev-parse-caret.sh
+++ b/t/t1511-rev-parse-caret.sh
@@ -6,14 +6,21 @@ test_description='tests for ref^{stuff}'
test_expect_success 'setup' '
echo blob >a-blob &&
- git tag -a -m blob blob-tag `git hash-object -w a-blob` &&
+ BLOB_SHA1=`git hash-object -w a-blob` &&
+ git tag -a -m blob blob-tag $BLOB_SHA1 &&
+ BLOB_TAG_SHA1=`git rev-parse --verify blob-tag` &&
mkdir a-tree &&
echo moreblobs >a-tree/another-blob &&
git add . &&
TREE_SHA1=`git write-tree` &&
git tag -a -m tree tree-tag "$TREE_SHA1" &&
+ TREE_TAG_SHA1=`git rev-parse --verify tree-tag` &&
git commit -m Initial &&
+ COMMIT_SHA1=`git rev-parse --verify HEAD` &&
git tag -a -m commit commit-tag &&
+ COMMIT_TAG_SHA1=`git rev-parse --verify commit-tag` &&
+ git tag -a -m tag tag-tag $COMMIT_TAG_SHA1 &&
+ TAG_TAG_SHA1=`git rev-parse --verify tag-tag` &&
git branch ref &&
git checkout master &&
echo modified >>a-blob &&
@@ -54,6 +61,26 @@ test_expect_success 'ref^{tree}' '
test_must_fail git rev-parse blob-tag^{tree}
'
+test_expect_success 'ref^{tag}' '
+ echo $BLOB_TAG_SHA1 >expected &&
+ git rev-parse --verify blob-tag^{tag} >actual &&
+ test_cmp expected actual &&
+ echo $TREE_TAG_SHA1 >expected &&
+ git rev-parse --verify tree-tag^{tag} >actual &&
+ test_cmp expected actual &&
+ echo $COMMIT_TAG_SHA1 >expected &&
+ git rev-parse --verify commit-tag^{tag} >actual &&
+ test_cmp expected actual &&
+ echo $TAG_TAG_SHA1 >expected &&
+ git rev-parse --verify tag-tag^{tag} >actual &&
+ test_cmp expected actual &&
+ test_must_fail git rev-parse --verify $BLOB_SHA1^{tag} &&
+ test_must_fail git rev-parse --verify $TREE_SHA1^{tag} &&
+ test_must_fail git rev-parse --verify $COMMIT_SHA1^{tag} &&
+ test_must_fail git rev-parse --verify rev^{tag} &&
+ true
+'
+
test_expect_success 'ref^{/.}' '
git rev-parse master >expected &&
git rev-parse master^{/.} >actual &&
--
1.8.4
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