1 files changed, 104 insertions, 15 deletions

diff --git a/libbuild2/install/rule.cxx b/libbuild2/install/rule.cxx
index 63d58a7..29888ae 100644
--- a/libbuild2/install/rule.cxx
+++ b/libbuild2/install/rule.cxx
@@ -93,8 +93,23 @@ namespace build2
     recipe alias_rule::
     apply (action a, target& t, match_extra& me) const
     {
+      return apply_impl (a, t, me);
+    }
+
+    recipe alias_rule::
+    apply (action, target&) const
+    {
+      assert (false); // Never called.
+      return nullptr;
+    }
+
+    recipe alias_rule::
+    apply_impl (action a, target& t, match_extra& me, bool reapply) const
+    {
       tracer trace ("install::alias_rule::apply");
 
+      assert (!reapply || a.operation () != update_id);
+
       // Pass-through to our installable prerequisites.
       //
       // @@ Shouldn't we do match in parallel (here and below)?
@@ -105,6 +120,8 @@ namespace build2
       auto pms (group_prerequisite_members (a, t, members_mode::never));
       for (auto i (pms.begin ()), e (pms.end ()); i != e; ++i)
       {
+        // NOTE: see essentially the same logic in reapply_impl() below.
+        //
         const prerequisite& p (i->prerequisite);
 
         // Ignore excluded.
@@ -131,12 +148,14 @@ namespace build2
         pair<const target*, uint64_t> fr (filter (*is, a, t, i, me));
 
         const target* pt (fr.first);
+        uint64_t options (fr.second);
+
+        lookup l;
+
         if (pt == nullptr)
         {
           l5 ([&]{trace << "ignoring " << p << " (filtered out)";});
-          continue;
         }
-
         // Check if this prerequisite is explicitly "not installable", that
         // is, there is the 'install' variable and its value is false.
         //
@@ -148,38 +167,108 @@ namespace build2
         //
         // Note: not the same as lookup_install() above.
         //
-        auto l ((*pt)[var_install (*p.scope.root_scope ())]);
-        if (l && cast<path> (l).string () == "false")
+        else if ((l = (*pt)[var_install (*p.scope.root_scope ())]) &&
+                 cast<path> (l).string () == "false")
         {
           l5 ([&]{trace << "ignoring " << *pt << " (not installable)";});
-          continue;
+          pt = nullptr;
         }
-
-        uint64_t options (fr.second);
-
         // If this is not a file-based target (e.g., a target group such as
         // libu{}) then ignore it if there is no rule to install.
         //
-        if (pt->is_a<file> ())
+        else if (pt->is_a<file> ())
+        {
           match_sync (a, *pt, options);
+        }
         else if (!try_match_sync (a, *pt, options).first)
         {
           l5 ([&]{trace << "ignoring " << *pt << " (no rule)";});
           pt = nullptr;
         }
 
-        if (pt != nullptr)
-          pts.push_back (prerequisite_target (pt, pi));
+        if (pt != nullptr || reapply)
+        {
+          // Use auxiliary data for a NULL entry to distinguish between
+          // filtered out (1) and ignored for other reasons (0).
+          //
+          pts.push_back (
+            prerequisite_target (pt, pi, fr.first == nullptr ? 1 : 0));
+        }
       }
 
       return default_recipe;
     }
 
-    recipe alias_rule::
-    apply (action, target&) const
+    void alias_rule::
+    reapply_impl (action a, target& t, match_extra& me) const
     {
-      assert (false); // Never called.
-      return nullptr;
+      tracer trace ("install::alias_rule::reapply");
+
+      assert (a.operation () != update_id);
+
+      optional<const scope*> is;
+
+      // Iterate over prerequisites and prerequisite targets in parallel.
+      //
+      auto& pts (t.prerequisite_targets[a]);
+      size_t j (0), n (pts.size ()), en (0);
+
+      auto pms (group_prerequisite_members (a, t, members_mode::never));
+      for (auto i (pms.begin ()), e (pms.end ());
+           i != e && j != n;
+           ++i, ++j, ++en)
+      {
+        // The same logic as in apply() above except that we skip
+        // prerequisites that were not filtered out.
+        //
+        const prerequisite& p (i->prerequisite);
+
+        include_type pi (include (a, t, p));
+        if (!pi)
+          continue;
+
+        if (p.proj)
+          continue;
+
+        prerequisite_target& pto (pts[j]);
+
+        if (pto.target != nullptr || pto.data == 0)
+          continue;
+
+        if (!is)
+          is = a.operation () != update_id ? install_scope (t) : nullptr;
+
+        pair<const target*, uint64_t> fr (filter (*is, a, t, i, me));
+
+        const target* pt (fr.first);
+        uint64_t options (fr.second);
+
+        lookup l;
+
+        if (pt == nullptr)
+        {
+          l5 ([&]{trace << "ignoring " << p << " (filtered out)";});
+        }
+        else if ((l = (*pt)[var_install (*p.scope.root_scope ())]) &&
+                 cast<path> (l).string () == "false")
+        {
+          l5 ([&]{trace << "ignoring " << *pt << " (not installable)";});
+          pt = nullptr;
+        }
+        else if (pt->is_a<file> ())
+        {
+          match_sync (a, *pt, options);
+        }
+        else if (!try_match_sync (a, *pt, options).first)
+        {
+          l5 ([&]{trace << "ignoring " << *pt << " (no rule)";});
+          pt = nullptr;
+        }
+
+        pto = prerequisite_target (pt, pi, fr.first == nullptr ? 1 : 0);
+      }
+
+      assert (en == n); // Did not call apply() with true for reapply?
     }
 
     // group_rule