Allow overriding apply(match_extra) version in cxx_rule_v1

1 files changed, 14 insertions, 0 deletions

diff --git a/libbuild2/adhoc-rule-cxx.cxx b/libbuild2/adhoc-rule-cxx.cxx
index 637f9af..2ac97eb 100644
--- a/libbuild2/adhoc-rule-cxx.cxx
+++ b/libbuild2/adhoc-rule-cxx.cxx
@@ -25,6 +25,13 @@ namespace build2
     return true;
   }
 
+  recipe cxx_rule_v1::
+  apply (action, target&) const
+  {
+    assert (false); // This (or the match_extra version) must be overriden.
+    return empty_recipe;
+  }
+
   // adhoc_cxx_rule
   //
   adhoc_cxx_rule::
@@ -699,6 +706,13 @@ namespace build2
       return group_recipe; // Execute the group's recipe.
     }
 
+    // Note that while we probably could call pattern's apply_group_members()
+    // here, apply_group_prerequisites() is normally called after adding
+    // prerequisites but before matching, which can only be done from the
+    // rule's implementation. Also, for apply_group_members(), there is the
+    // explicit group special case which may also require custom logic.
+    // So it feels best to leave both to the implementation.
+
     return impl.load (memory_order_relaxed)->apply (a, t, me);
   }