Add default constructors to *_rule classes to make older clang happy

1 files changed, 2 insertions, 0 deletions

diff --git a/build2/dist/rule b/build2/dist/rule
index 4953394..db8e731 100644
--- a/build2/dist/rule
+++ b/build2/dist/rule
@@ -19,6 +19,8 @@ namespace build2
     class rule: public build2::rule
     {
     public:
+      rule () {}
+
       virtual match_result
       match (action, target&, const string&) const override;