refspec: make @ a synonym of HEAD

Since commit 9ba89f4 git learned how to push to a remote branch using
the source @, for example:

  git push origin @:master

However, if the right-hand side is missing, the push fails:

  git push origin @

It is obvious what is the desired behavior, and allowing the push makes
things more consistent.

Additionally, @:master now has the same semantics as HEAD:master.

Signed-off-by: Felipe Contreras <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: felipec

refspec.c

@@ -71,7 +71,10 @@ static int parse_refspec(struct refspec_item *item, const char *refspec, int fet
 	}
 
 	item->pattern = is_glob;
-	item->src = xstrndup(lhs, llen);
+	if (llen == 1 && *lhs == '@')
+		item->src = xstrdup("HEAD");
+	else
+		item->src = xstrndup(lhs, llen);
 	flags = REFNAME_ALLOW_ONELEVEL | (is_glob ? REFNAME_REFSPEC_PATTERN : 0);
 
 	if (item->negative) {

t/t5511-refspec.sh

@@ -58,6 +58,8 @@ test_refspec fetch 'HEAD~4:refs/remotes/frotz/new'		invalid
 
 test_refspec push 'HEAD'
 test_refspec fetch 'HEAD'
+test_refspec push '@'
+test_refspec fetch '@'
 test_refspec push 'refs/heads/ nitfol'				invalid
 test_refspec fetch 'refs/heads/ nitfol'				invalid
 

t/t5516-fetch-push.sh

@@ -436,71 +436,76 @@ test_expect_success 'push ref expression with non-existent, incomplete dest' '
 
 '
 
-test_expect_success 'push with HEAD' '
+for head in HEAD @
+do
 
-	mk_test testrepo heads/master &&
-	git checkout master &&
-	git push testrepo HEAD &&
-	check_push_result testrepo $the_commit heads/master
+	test_expect_success "push with $head" '
 
-'
+		mk_test testrepo heads/master &&
+		git checkout master &&
+		git push testrepo $head &&
+		check_push_result testrepo $the_commit heads/master
 
-test_expect_success 'push with HEAD nonexisting at remote' '
+	'
 
-	mk_test testrepo heads/master &&
-	git checkout -b local master &&
-	test_when_finished "git checkout master; git branch -D local" &&
-	git push testrepo HEAD &&
-	check_push_result testrepo $the_commit heads/local
-'
+	test_expect_success "push with $head nonexisting at remote" '
 
-test_expect_success 'push with +HEAD' '
+		mk_test testrepo heads/master &&
+		git checkout -b local master &&
+		test_when_finished "git checkout master; git branch -D local" &&
+		git push testrepo $head &&
+		check_push_result testrepo $the_commit heads/local
+	'
 
-	mk_test testrepo heads/master &&
-	git checkout -b local master &&
-	test_when_finished "git checkout master; git branch -D local" &&
-	git push testrepo master local &&
-	check_push_result testrepo $the_commit heads/master &&
-	check_push_result testrepo $the_commit heads/local &&
+	test_expect_success "push with +$head" '
 
-	# Without force rewinding should fail
-	git reset --hard HEAD^ &&
-	test_must_fail git push testrepo HEAD &&
-	check_push_result testrepo $the_commit heads/local &&
+		mk_test testrepo heads/master &&
+		git checkout -b local master &&
+		test_when_finished "git checkout master; git branch -D local" &&
+		git push testrepo master local &&
+		check_push_result testrepo $the_commit heads/master &&
+		check_push_result testrepo $the_commit heads/local &&
 
-	# With force rewinding should succeed
-	git push testrepo +HEAD &&
-	check_push_result testrepo $the_first_commit heads/local
+		# Without force rewinding should fail
+		git reset --hard $head^ &&
+		test_must_fail git push testrepo $head &&
+		check_push_result testrepo $the_commit heads/local &&
 
-'
+		# With force rewinding should succeed
+		git push testrepo +$head &&
+		check_push_result testrepo $the_first_commit heads/local
 
-test_expect_success 'push HEAD with non-existent, incomplete dest' '
+	'
 
-	mk_test testrepo &&
-	git checkout master &&
-	git push testrepo HEAD:branch &&
-	check_push_result testrepo $the_commit heads/branch
+	test_expect_success "push $head with non-existent, incomplete dest" '
 
-'
+		mk_test testrepo &&
+		git checkout master &&
+		git push testrepo $head:branch &&
+		check_push_result testrepo $the_commit heads/branch
 
-test_expect_success 'push with config remote.*.push = HEAD' '
+	'
 
-	mk_test testrepo heads/local &&
-	git checkout master &&
-	git branch -f local $the_commit &&
-	test_when_finished "git branch -D local" &&
-	(
-		cd testrepo &&
-		git checkout local &&
-		git reset --hard $the_first_commit
-	) &&
-	test_config remote.there.url testrepo &&
-	test_config remote.there.push HEAD &&
-	test_config branch.master.remote there &&
-	git push &&
-	check_push_result testrepo $the_commit heads/master &&
-	check_push_result testrepo $the_first_commit heads/local
-'
+	test_expect_success "push with config remote.*.push = $head" '
+
+		mk_test testrepo heads/local &&
+		git checkout master &&
+		git branch -f local $the_commit &&
+		test_when_finished "git branch -D local" &&
+		(
+			cd testrepo &&
+			git checkout local &&
+			git reset --hard $the_first_commit
+		) &&
+		test_config remote.there.url testrepo &&
+		test_config remote.there.push $head &&
+		test_config branch.master.remote there &&
+		git push &&
+		check_push_result testrepo $the_commit heads/master &&
+		check_push_result testrepo $the_first_commit heads/local
+	'
+
+done
 
 test_expect_success 'push with remote.pushdefault' '
 	mk_test up_repo heads/master &&