X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topgit.git;a=blobdiff_plain;f=tg-depend.sh;h=474ccda4e098a2046a2e60a52d5addad4b007f81;hp=6d98b5f556f0e1622cc0cfd6297561e9e9255d38;hb=refs%2Ftop-bases%2Ffixes%2Fexport--b-deps;hpb=bd0a68e9716f944cb12848bee4649958f7db7eb8

diff --git a/tg-depend.sh b/tg-depend.sh
index 6d98b5f..474ccda 100644
--- a/tg-depend.sh
+++ b/tg-depend.sh
@@ -42,9 +42,24 @@ done
 branchrev="$(git rev-parse --verify "$name" 2>/dev/null)" ||
 	die "invalid branch name: $name"
 
+# Check that we are on a TopGit branch.
+current_name="$(git symbolic-ref HEAD | sed 's#^refs/\(heads\|top-bases\)/##')"
+current_base_rev="$(git rev-parse --short --verify "refs/top-bases/$current_name" 2>/dev/null)" ||
+	die "not a TopGit-controlled branch"
+
 ## Record new dependency
 depend_add()
 {
+	[ "$name" = "$current_name" ] &&
+		die "$name cannot depend on itself."
+
+	{ $tg summary --deps; echo "$current_name" "$name"; } |
+		tsort >/dev/null ||
+		die "tg: that dependency would introduce a dependency loop"
+
+	grep -F -x -e "$name" "$root_dir/.topdeps" >/dev/null &&
+		die "tg: $current_name already depends on $name"
+
 	echo "$name" >>"$root_dir/.topdeps"
 	git add -f "$root_dir/.topdeps"
 	git commit -m"New TopGit dependency: $name"