Merge branch 'eb/hash-transition'

Work to support a repository that work with both SHA-1 and SHA-256
hash algorithms has started.

* eb/hash-transition: (30 commits)
  t1016-compatObjectFormat: add tests to verify the conversion between objects
  t1006: test oid compatibility with cat-file
  t1006: rename sha1 to oid
  test-lib: compute the compatibility hash so tests may use it
  builtin/ls-tree: let the oid determine the output algorithm
  object-file: handle compat objects in check_object_signature
  tree-walk: init_tree_desc take an oid to get the hash algorithm
  builtin/cat-file: let the oid determine the output algorithm
  rev-parse: add an --output-object-format parameter
  repository: implement extensions.compatObjectFormat
  object-file: update object_info_extended to reencode objects
  object-file-convert: convert commits that embed signed tags
  object-file-convert: convert commit objects when writing
  object-file-convert: don't leak when converting tag objects
  object-file-convert: convert tag objects when writing
  object-file-convert: add a function to convert trees between algorithms
  object: factor out parse_mode out of fast-import and tree-walk into in object.h
  cache: add a function to read an OID of a specific algorithm
  tag: sign both hashes
  commit: export add_header_signature to support handling signatures on tags
  ...

1 files changed, 10 insertions, 2 deletions

diff --git a/oid-array.c b/oid-array.c
index 8e4717746c..1f36651754 100644
--- a/oid-array.c
+++ b/oid-array.c
@@ -6,12 +6,20 @@ void oid_array_append(struct oid_array *array, const struct object_id *oid)
 {
 	ALLOC_GROW(array->oid, array->nr + 1, array->alloc);
 	oidcpy(&array->oid[array->nr++], oid);
+	if (!oid->algo)
+		oid_set_algo(&array->oid[array->nr - 1], the_hash_algo);
 	array->sorted = 0;
 }
 
-static int void_hashcmp(const void *a, const void *b)
+static int void_hashcmp(const void *va, const void *vb)
 {
-	return oidcmp(a, b);
+	const struct object_id *a = va, *b = vb;
+	int ret;
+	if (a->algo == b->algo)
+		ret = oidcmp(a, b);
+	else
+		ret = a->algo > b->algo ? 1 : -1;
+	return ret;
 }
 
 void oid_array_sort(struct oid_array *array)