5 files changed, 20 insertions, 0 deletions
diff --git a/build2/bin/rule b/build2/bin/rule
index f733e5a..5031be1 100644
--- a/build2/bin/rule
+++ b/build2/bin/rule
@@ -17,6 +17,8 @@ namespace build2
     class obj_rule: public rule
     {
     public:
+      obj_rule () {}
+
       virtual match_result
       match (action, target&, const string& hint) const override;
 
@@ -27,6 +29,8 @@ namespace build2
     class lib_rule: public rule
     {
     public:
+      lib_rule () {}
+
       virtual match_result
       match (action, target&, const string& hint) const override;
 
diff --git a/build2/cli/rule b/build2/cli/rule
index 6cbbb9b..a46163b 100644
--- a/build2/cli/rule
+++ b/build2/cli/rule
@@ -17,6 +17,8 @@ namespace build2
     class compile: public rule
     {
     public:
+      compile () {}
+
       virtual match_result
       match (action, target&, const string& hint) const override;
 
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;
 
diff --git a/build2/install/rule b/build2/install/rule
index 1345dbd..aad5ee4 100644
--- a/build2/install/rule
+++ b/build2/install/rule
@@ -19,6 +19,8 @@ namespace build2
     class alias_rule: public rule
     {
     public:
+      alias_rule () {}
+
       virtual match_result
       match (action, target&, const string&) const override;
 
@@ -31,6 +33,8 @@ namespace build2
     class file_rule: public rule
     {
     public:
+      file_rule () {}
+
       virtual match_result
       match (action, target&, const string&) const override;
 
diff --git a/build2/rule b/build2/rule
index fbf3dcc..d01df6b 100644
--- a/build2/rule
+++ b/build2/rule
@@ -48,6 +48,8 @@ namespace build2
   class file_rule: public rule
   {
   public:
+    file_rule () {}
+
     virtual match_result
     match (action, target&, const string& hint) const override;
 
@@ -60,6 +62,8 @@ namespace build2
   class alias_rule: public rule
   {
   public:
+    alias_rule () {}
+
     virtual match_result
     match (action, target&, const string& hint) const override;
 
@@ -72,6 +76,8 @@ namespace build2
   class fsdir_rule: public rule
   {
   public:
+    fsdir_rule () {}
+
     virtual match_result
     match (action, target&, const string& hint) const override;
 
@@ -92,6 +98,8 @@ namespace build2
   class fallback_rule: public build2::rule
   {
   public:
+    fallback_rule () {}
+
     virtual match_result
     match (action, target&, const string&) const override {return true;}