submodule summary: Don't barf when invoked in an empty repo

When invoking "git submodule summary" in an empty repo (which can be
indirectly done by setting status.submodulesummary = true), it currently
emits an error message (via "git diff-index") since HEAD points to an
unborn branch.

This patch adds handling of the HEAD-points-to-unborn-branch special case,
so that "git submodule summary" no longer emits this error message.

The patch also adds a test case that verifies the fix.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-submodule.sh b/git-submodule.sh
index 664f21721cb876eed7da167744066d834521c825..5869c00f2d5db4d8316002267a8605096357d5ed 100755 (executable)
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -553,12 +553,15 @@ cmd_summary() {
 
        test $summary_limit = 0 && return
 
-       if rev=$(git rev-parse -q --verify "$1^0")
+       if rev=$(git rev-parse -q --verify --default HEAD ${1+"$1"})
        then
                head=$rev
                shift
+       elif test -z "$1" -o "$1" = "HEAD"
+       then
+               return
        else
-               head=HEAD
+               head="HEAD"
        fi
 
        if [ -n "$files" ]

diff --git a/t/t7401-submodule-summary.sh b/t/t7401-submodule-summary.sh
index d3c039f724c3a1247417b5fd29d6bd50a88f54be..cee319da0ae6ef9ec3b220adbb178e116713db2a 100755 (executable)
--- a/t/t7401-submodule-summary.sh
+++ b/t/t7401-submodule-summary.sh
@@ -227,4 +227,11 @@ test_expect_success 'fail when using --files together with --cached' "
     test_must_fail git submodule summary --files --cached
 "
 
+test_expect_success 'should not fail in an empty repo' "
+    git init xyzzy &&
+    cd xyzzy &&
+    git submodule summary >output 2>&1 &&
+    test_cmp output /dev/null
+"
+
 test_done