git-archive: make tar the default format

As noted by Junio, --format=tar should be assumed if no format
was specified.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-archive.txt

@@ -30,7 +30,8 @@ OPTIONS
 -------
 
 --format=<fmt>::
-	Format of the resulting archive: 'tar', 'zip'...
+	Format of the resulting archive: 'tar', 'zip'...  The default
+	is 'tar'.
 
 --list::
 	Show all available formats.

builtin-archive.c

@@ -149,7 +149,7 @@ int parse_archive_args(int argc, const char **argv, struct archiver *ar)
 {
 	const char *extra_argv[MAX_EXTRA_ARGS];
 	int extra_argc = 0;
-	const char *format = NULL; /* might want to default to "tar" */
+	const char *format = "tar";
 	const char *base = "";
 	int verbose = 0;
 	int i;
@@ -190,8 +190,6 @@ int parse_archive_args(int argc, const char **argv, struct archiver *ar)
 	/* We need at least one parameter -- tree-ish */
 	if (argc - 1 < i)
 		usage(archive_usage);
-	if (!format)
-		die("You must specify an archive format");
 	if (init_archiver(format, ar) < 0)
 		die("Unknown archive format '%s'", format);
 

t/t5000-tar-tree.sh

@@ -49,9 +49,17 @@ test_expect_success \
      git-update-ref HEAD $(TZ=GMT GIT_COMMITTER_DATE="2005-05-27 22:00:00" \
      git-commit-tree $treeid </dev/null)'
 
+test_expect_success \
+    'git-archive' \
+    'git-archive HEAD >b.tar'
+
 test_expect_success \
     'git-tar-tree' \
-    'git-tar-tree HEAD >b.tar'
+    'git-tar-tree HEAD >b2.tar'
+
+test_expect_success \
+    'git-archive vs. git-tar-tree' \
+    'diff b.tar b2.tar'
 
 test_expect_success \
     'validate file modification time' \