Merge branch 'mb/fast-import-reference-pending'

The 'from' command in 'git fast-import' has been updated to
correctly resolve references to newly created commits and tags by
checking the internal object table, preventing a crash when the
objects are not yet available in the object database.

* mb/fast-import-reference-pending:
  fast-import: allow 'from' to reference new commits and tags by oid

builtin/fast-import.c

@@ -292,6 +292,9 @@ static void fast_import_state_init(struct fast_import_state *state,
 	state->option = option;
 }
 
+static struct object_entry *dereference(struct object_entry *oe,
+					struct object_id *oid);
+
 static void parse_argv(struct fast_import_state *state);
 static void parse_get_mark(struct fast_import_state *state, const char *p);
 static void parse_cat_blob(struct fast_import_state *state, const char *p);
@@ -2654,12 +2657,20 @@ static void parse_from_existing(struct branch *b)
 		oidclr(&b->branch_tree.versions[1].oid, the_repository->hash_algo);
 	} else {
 		unsigned long size;
-		size_t size_st = 0;
 		char *buf;
+		struct object_entry *e = find_object(&b->oid);
 
-		buf = odb_read_object_peeled(the_repository->objects, &b->oid,
-					     OBJ_COMMIT, &size_st, &b->oid);
-		size = cast_size_t_to_ulong(size_st);
+		while (e && e->type == OBJ_TAG)
+			e = dereference(e, &b->oid);
+
+		if (e && e->type == OBJ_COMMIT && e->pack_id != MAX_PACK_ID) {
+			buf = gfi_unpack_entry(e, &size);
+		} else {
+			size_t size_st = 0;
+			buf = odb_read_object_peeled(the_repository->objects, &b->oid,
+						     OBJ_COMMIT, &size_st, &b->oid);
+			size = cast_size_t_to_ulong(size_st);
+		}
 		parse_from_commit(b, buf, size);
 		free(buf);
 	}

t/t9300-fast-import.sh

@@ -3938,4 +3938,47 @@ test_expect_success 'Y: rewrite submodules' '
 	)
 '
 
+test_expect_success 'Y: reference pending tag or commit' '
+	test_oid_cache <<-EOF &&
+	pending_commit sha1:85b46dd918355ff17b4109ec738723d42f235a04
+	pending_commit sha256:17e650f097a4db6fe069c96935360d3ccc9b35c4018728c5f311a4217c2ced3d
+	pending_tag sha1:ec6c4db71feb5f66615214dad2324ce030e777a7
+	pending_tag sha256:85edc5eac315bc680677b2fc71622bd77476f057eb8dc8ed6a497803a24f1f46
+	EOF
+
+	git init reference-pending &&
+	(
+		cd reference-pending &&
+		git fast-import <<-EOF
+		commit refs/heads/main
+		committer A U Thor <author@example.com> 1712563200 +0000
+		data 14
+		commit message
+		M 644 inline test file
+		data 14
+		dummy content
+
+		tag newtag
+		from $(test_oid pending_commit)
+		tagger A U Thor <author@example.com> 1712563300 +0000
+		data 11
+		tag message
+		# no emty line after tag data!
+		reset refs/heads/other
+		from $(test_oid pending_tag)
+
+		commit refs/heads/further
+		committer A U Thor <author@example.com> 1712563400 +0000
+		data 21
+		what about 2nd commit
+		from $(test_oid pending_commit)
+		M 644 inline other test file
+		data 19
+		more dummy content
+
+		done
+		EOF
+	)
+'
+
 test_done