From 934f2a9a90c5cad3cdc8a66b50c17827a3ddbcee Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 20 Jan 2018 13:46:11 +0200
Subject: Get rid of action rule override semantics

Instead we now have two more or less separate match states for outer and
inner parts of an action.
---
 build2/variable.cxx | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

(limited to 'build2/variable.cxx')

diff --git a/build2/variable.cxx b/build2/variable.cxx
index d1f95c5..eb74aad 100644
--- a/build2/variable.cxx
+++ b/build2/variable.cxx
@@ -302,7 +302,7 @@ namespace build2
   }
 
   void
-  typify (value& v, const value_type& t, const variable* var)
+  typify (value& v, const value_type& t, const variable* var, memory_order mo)
   {
     if (v.type == nullptr)
     {
@@ -312,11 +312,16 @@ namespace build2
         //
         names ns (move (v).as<names> ());
         v = nullptr;
-        v.type = &t;
-        v.assign (move (ns), var);
+
+        // Use value_type::assign directly to delay v.type change.
+        //
+        t.assign (v, move (ns), var);
+        v.null = false;
       }
       else
         v.type = &t;
+
+      v.type.store (&t, mo);
     }
     else if (v.type != &t)
     {
@@ -342,8 +347,10 @@ namespace build2
       variable_cache_mutex_shard[
         hash<value*> () (&v) % variable_cache_mutex_shard_size]);
 
+    // Note: v.type is rechecked by typify() under lock.
+    //
     ulock l (m);
-    typify (v, t, var); // v.type is rechecked by typify(), stored under lock.
+    typify (v, t, var, memory_order_release);
   }
 
   void
-- 
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