Merge branch 'sb/describe-blob'

"git describe" was taught to dig trees deeper to find a
<commit-ish>:<path> that refers to a given blob object.

* sb/describe-blob:
  builtin/describe.c: describe a blob
  builtin/describe.c: factor out describe_commit
  builtin/describe.c: print debug statements earlier
  builtin/describe.c: rename `oid` to avoid variable shadowing
  revision.h: introduce blob/tree walking in order of the commits
  list-objects.c: factor out traverse_trees_and_blobs
  t6120: fix typo in test name

2 files changed, 112 insertions, 1 deletions

diff --git a/t/t6100-rev-list-in-order.sh b/t/t6100-rev-list-in-order.sh
new file mode 100755
index 0000000..b2bb0a7
--- /dev/null
+++ b/t/t6100-rev-list-in-order.sh
@@ -0,0 +1,77 @@
+#!/bin/sh
+
+test_description='rev-list testing in-commit-order'
+
+. ./test-lib.sh
+
+test_expect_success 'setup a commit history with trees, blobs' '
+	for x in one two three four
+	do
+		echo $x >$x &&
+		git add $x &&
+		git commit -m "add file $x" ||
+		return 1
+	done &&
+	for x in four three
+	do
+		git rm $x &&
+		git commit -m "remove $x" ||
+		return 1
+	done
+'
+
+test_expect_success 'rev-list --in-commit-order' '
+	git rev-list --in-commit-order --objects HEAD >actual.raw &&
+	cut -c 1-40 >actual <actual.raw &&
+
+	git cat-file --batch-check="%(objectname)" >expect.raw <<-\EOF &&
+		HEAD^{commit}
+		HEAD^{tree}
+		HEAD^{tree}:one
+		HEAD^{tree}:two
+		HEAD~1^{commit}
+		HEAD~1^{tree}
+		HEAD~1^{tree}:three
+		HEAD~2^{commit}
+		HEAD~2^{tree}
+		HEAD~2^{tree}:four
+		HEAD~3^{commit}
+		# HEAD~3^{tree} skipped, same as HEAD~1^{tree}
+		HEAD~4^{commit}
+		# HEAD~4^{tree} skipped, same as HEAD^{tree}
+		HEAD~5^{commit}
+		HEAD~5^{tree}
+	EOF
+	grep -v "#" >expect <expect.raw &&
+
+	test_cmp expect actual
+'
+
+test_expect_success 'rev-list lists blobs and trees after commits' '
+	git rev-list --objects HEAD >actual.raw &&
+	cut -c 1-40 >actual <actual.raw &&
+
+	git cat-file --batch-check="%(objectname)" >expect.raw <<-\EOF &&
+		HEAD^{commit}
+		HEAD~1^{commit}
+		HEAD~2^{commit}
+		HEAD~3^{commit}
+		HEAD~4^{commit}
+		HEAD~5^{commit}
+		HEAD^{tree}
+		HEAD^{tree}:one
+		HEAD^{tree}:two
+		HEAD~1^{tree}
+		HEAD~1^{tree}:three
+		HEAD~2^{tree}
+		HEAD~2^{tree}:four
+		# HEAD~3^{tree} skipped, same as HEAD~1^{tree}
+		# HEAD~4^{tree} skipped, same as HEAD^{tree}
+		HEAD~5^{tree}
+	EOF
+	grep -v "#" >expect <expect.raw &&
+
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t6120-describe.sh b/t/t6120-describe.sh
index 1c0e865..3e3fb46 100755
--- a/t/t6120-describe.sh
+++ b/t/t6120-describe.sh
@@ -304,12 +304,46 @@ test_expect_success 'describe chokes on severely broken submodules' '
 	mv .git/modules/sub1/ .git/modules/sub_moved &&
 	test_must_fail git describe --dirty
 '
-test_expect_success 'describe ignoring a borken submodule' '
+test_expect_success 'describe ignoring a broken submodule' '
 	git describe --broken >out &&
 	test_when_finished "mv .git/modules/sub_moved .git/modules/sub1" &&
 	grep broken out
 '
 
+test_expect_success 'describe a blob at a directly tagged commit' '
+	echo "make it a unique blob" >file &&
+	git add file && git commit -m "content in file" &&
+	git tag -a -m "latest annotated tag" unique-file &&
+	git describe HEAD:file >actual &&
+	echo "unique-file:file" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'describe a blob with its first introduction' '
+	git commit --allow-empty -m "empty commit" &&
+	git rm file &&
+	git commit -m "delete blob" &&
+	git revert HEAD &&
+	git commit --allow-empty -m "empty commit" &&
+	git describe HEAD:file >actual &&
+	echo "unique-file:file" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'describe directly tagged blob' '
+	git tag test-blob unique-file:file &&
+	git describe test-blob >actual &&
+	echo "unique-file:file" >expect &&
+	# suboptimal: we rather want to see "test-blob"
+	test_cmp expect actual
+'
+
+test_expect_success 'describe tag object' '
+	git tag test-blob-1 -a -m msg unique-file:file &&
+	test_must_fail git describe test-blob-1 2>actual &&
+	test_i18ngrep "fatal: test-blob-1 is neither a commit nor blob" actual
+'
+
 test_expect_failure ULIMIT_STACK_SIZE 'name-rev works in a deep repo' '
 	i=1 &&
 	while test $i -lt 8000