Add hook for vendor-specific __traits

ddmd/hooks.d

@@ -0,0 +1,16 @@
+// Compiler implementation of the D programming language
+// Copyright (c) 1999-2016 by Digital Mars
+// All Rights Reserved
+// http://www.digitalmars.com
+// Distributed under the Boost Software License, Version 1.0.
+// http://www.boost.org/LICENSE_1_0.txt
+
+module ddmd.hooks;
+
+import ddmd.dscope;
+import ddmd.expression;
+
+Expression semanticTraitsHook(TraitsExp e, Scope* sc)
+{
+    return null;
+}

ddmd/traits.d

@@ -27,6 +27,7 @@ import ddmd.expression;
 import ddmd.func;
 import ddmd.globals;
 import ddmd.hdrgen;
+import ddmd.hooks;
 import ddmd.id;
 import ddmd.identifier;
 import ddmd.mtype;
@@ -1191,6 +1192,10 @@ extern (C++) Expression semanticTraits(TraitsExp e, Scope* sc)
     {
         return pointerBitmap(e);
     }
+    if (Expression ret = semanticTraitsHook(e, sc))
+    {
+        return ret;
+    }
 
     extern (D) void* trait_search_fp(const(char)* seed, ref int cost)
     {