6 files changed, 41 insertions, 38 deletions
diff --git a/libbuild2/dist/init.cxx b/libbuild2/dist/init.cxx
index 9de84ce..26ff86d 100644
--- a/libbuild2/dist/init.cxx
+++ b/libbuild2/dist/init.cxx
@@ -21,6 +21,8 @@ namespace build2
 {
   namespace dist
   {
+    static const rule rule_;
+
     void
     boot (scope& rs, const location&, module_boot_extra& extra)
     {
@@ -194,7 +196,7 @@ namespace build2
           const location& l,
           bool first,
           bool,
-          module_init_extra& extra)
+          module_init_extra&)
     {
       tracer trace ("dist::init");
 
@@ -206,19 +208,13 @@ namespace build2
 
       l5 ([&]{trace << "for " << rs;});
 
-      module& mod (extra.module_as<module> ());
-
       auto& vp (rs.var_pool (true /* public */)); // All qualified.
 
       // Register our wildcard rule. Do it explicitly for the alias to prevent
       // something like insert<target>(dist_id, test_id) taking precedence.
       //
-      {
-        const rule& r (mod);
-
-        rs.insert_rule<target> (dist_id, 0, "dist",       r);
-        rs.insert_rule<alias>  (dist_id, 0, "dist.alias", r);
-      }
+      rs.insert_rule<target> (dist_id, 0, "dist",       rule_);
+      rs.insert_rule<alias>  (dist_id, 0, "dist.alias", rule_);
 
       // We need this rule for out-of-any-project dependencies (for example,
       // executables imported from /usr/bin, etc). We are registering it on
diff --git a/libbuild2/dist/module.hxx b/libbuild2/dist/module.hxx
index dbe2a3e..da97939 100644
--- a/libbuild2/dist/module.hxx
+++ b/libbuild2/dist/module.hxx
@@ -11,7 +11,6 @@
 #include <libbuild2/variable.hxx>
 
 #include <libbuild2/dist/types.hxx>
-#include <libbuild2/dist/rule.hxx>
 
 #include <libbuild2/export.hxx>
 
@@ -19,8 +18,7 @@ namespace build2
 {
   namespace dist
   {
-    class LIBBUILD2_SYMEXPORT module: public build2::module,
-                                      public rule
+    class LIBBUILD2_SYMEXPORT module: public build2::module
     {
     public:
       static const string name;
@@ -43,9 +41,9 @@ namespace build2
         adhoc.push_back (move (f));
       }
 
-      // List of postponed prerequisites.
+      // List of postponed prerequisites (see rule for details).
       //
-      postponed_prerequisites postponed;
+      mutable postponed_prerequisites postponed;
 
       // Distribution post-processing callbacks.
       //
@@ -79,8 +77,7 @@ namespace build2
       // Implementation details.
       //
     public:
-      module (const variable& v_d_p)
-        : rule (postponed), var_dist_package (v_d_p) {}
+      module (const variable& v_d_p): var_dist_package (v_d_p) {}
 
     public:
       bool distributed = false; // True if this project is being distributed.
diff --git a/libbuild2/dist/operation.cxx b/libbuild2/dist/operation.cxx
index e5c9307..af7b40b 100644
--- a/libbuild2/dist/operation.cxx
+++ b/libbuild2/dist/operation.cxx
@@ -16,6 +16,7 @@
 #include <libbuild2/diagnostics.hxx>
 
 #include <libbuild2/dist/types.hxx>
+#include <libbuild2/dist/rule.hxx>
 #include <libbuild2/dist/module.hxx>
 
 using namespace std;
@@ -237,10 +238,7 @@ namespace build2
         fail << "unknown distribution package name" <<
           info << "did you forget to set dist.package?";
 
-      // Need non-const in order to clear postponed. This is safe since only
-      // doing it when running serially.
-      //
-      module& mod (const_cast<module&> (*rs.find_module<module> (module::name)));
+      const module& mod (*rs.find_module<module> (module::name));
 
       const string& dist_package (cast<string> (l));
       const process_path& dist_cmd (cast<process_path> (rs.vars["dist.cmd"]));
@@ -301,9 +299,7 @@ namespace build2
             for (auto i (mod.postponed.list.begin ());
                  i != mod.postponed.list.end ();
                  ++i)
-            {
-              rule::match_postponed (i->action, i->target, i->prereq);
-            }
+              rule::match_postponed (*i);
           }
         };
 
diff --git a/libbuild2/dist/rule.cxx b/libbuild2/dist/rule.cxx
index 7233eba..736490e 100644
--- a/libbuild2/dist/rule.cxx
+++ b/libbuild2/dist/rule.cxx
@@ -8,6 +8,9 @@
 #include <libbuild2/algorithm.hxx>
 #include <libbuild2/diagnostics.hxx>
 
+#include <libbuild2/dist/types.hxx>
+#include <libbuild2/dist/module.hxx>
+
 using namespace std;
 
 namespace build2
@@ -91,8 +94,11 @@ namespace build2
               // may be unknown because we haven't matched the lib{} group
               // yet. So we postpone this for later (see match_postponed()).
               //
-              mlock l (postponed_.mutex);
-              postponed_.list.push_back (postponed_prerequisite {a, t, p,});
+              const module& mod (*rs.find_module<module> (module::name));
+
+              mlock l (mod.postponed.mutex);
+              mod.postponed.list.push_back (
+                postponed_prerequisite {a, t, p, t.state[a].rule->first});
               continue;
             }
 
@@ -112,19 +118,23 @@ namespace build2
     }
 
     void rule::
-    match_postponed (action a, const target& t, const prerequisite& p)
+    match_postponed (const postponed_prerequisite& pp)
     {
+      action a (pp.action);
+      const target& t (pp.target);
+      const prerequisite& p (pp.prereq);
+
       const prerequisite_key& k (p.key ());
       const target* pt (k.tk.type->search (t, k));
 
       if (pt == nullptr)
       {
         // Note that we do loose the diag frame that we normally get when
-        // failing during match. So let's mention the target manually.
+        // failing during match. So let's mention the target/rule manually.
         //
         fail << "prerequisite " << k << " is not existing source file nor "
              << "known output target" <<
-          info << "while applying rule dist to " << diag_do (a, t);
+          info << "while applying rule " << pp.rule << " to " << diag_do (a, t);
       }
 
       search_custom (p, *pt); // Cache.
diff --git a/libbuild2/dist/rule.hxx b/libbuild2/dist/rule.hxx
index ec6c41a..69ab3d9 100644
--- a/libbuild2/dist/rule.hxx
+++ b/libbuild2/dist/rule.hxx
@@ -13,6 +13,8 @@
 
 #include <libbuild2/dist/types.hxx>
 
+#include <libbuild2/export.hxx>
+
 namespace build2
 {
   namespace dist
@@ -21,27 +23,28 @@ namespace build2
     //
     // A custom rule (usually the same as perform_update) may be necessary to
     // establish group links (so that we see the dist variable set on a group)
-    // or to see through non-see-through groups (like lib{}; see the
-    // bin::lib_rule for an example). Note that in the latter case the rule
-    // should "see" all its members for the dist case.
+    // or to see through non-see-through groups (like lib{}, obj{}; see rule
+    // in the bin module for an example). Note that in the latter case the
+    // rule should "see" all its members for the dist case.
     //
-    class rule: public simple_rule
+    class LIBBUILD2_SYMEXPORT rule: public simple_rule
     {
     public:
-      explicit
-      rule (postponed_prerequisites& p): postponed_ (p) {}
+      rule () {}
 
+      // Always matches (returns true).
+      //
       virtual bool
       match (action, target&) const override;
 
+      // Matches all the prerequisites (including from group) and returns
+      // noop_recipe (which will never be executed).
+      //
       virtual recipe
       apply (action, target&) const override;
 
       static void
-      match_postponed (action, const target&, const prerequisite&);
-
-    private:
-      postponed_prerequisites& postponed_;
+      match_postponed (const postponed_prerequisite&);
     };
   }
 }
diff --git a/libbuild2/dist/types.hxx b/libbuild2/dist/types.hxx
index f3b1009..b833951 100644
--- a/libbuild2/dist/types.hxx
+++ b/libbuild2/dist/types.hxx
@@ -27,6 +27,7 @@ namespace build2
       build2::action                          action;
       reference_wrapper<const build2::target> target;
       reference_wrapper<const prerequisite>   prereq;
+      string                                  rule;
     };
 
     struct postponed_prerequisites