Type.fixTo: Always propagate the naked type to new variants

Author: ibuclaw

compiler/src/dmd/typesem.d

@@ -464,12 +464,17 @@ void check(Type _this)
  * For our new type '_this', which is type-constructed from t,
  * fill in the cto, ito, sto, scto, wto shortcuts.
  */
-void fixTo(Type _this, Type t)
+private void fixTo(Type _this, Type t)
 {
     // If fixing this: immutable(T*) by t: immutable(T)*,
     // cache t to this.xto won't break transitivity.
     Type mto = null;
     Type tn = _this.nextOf();
+    if (_this.mod || t.mod)
+    {
+        _this.getMcache();
+        t.getMcache();
+    }
     if (!tn || _this.ty != Tsarray && tn.mod == t.nextOf().mod)
     {
         switch (t.mod)
@@ -479,42 +484,42 @@ void fixTo(Type _this, Type t)
             break;
 
         case MODFlags.const_:
-            _this.getMcache();
+            mto = t.mcache.cto;
             _this.mcache.cto = t;
             break;
 
         case MODFlags.wild:
-            _this.getMcache();
+            mto = t.mcache.wto;
             _this.mcache.wto = t;
             break;
 
         case MODFlags.wildconst:
-            _this.getMcache();
+            mto = t.mcache.wcto;
             _this.mcache.wcto = t;
             break;
 
         case MODFlags.shared_:
-            _this.getMcache();
+            mto = t.mcache.sto;
             _this.mcache.sto = t;
             break;
 
         case MODFlags.shared_ | MODFlags.const_:
-            _this.getMcache();
+            mto = t.mcache.scto;
             _this.mcache.scto = t;
             break;
 
         case MODFlags.shared_ | MODFlags.wild:
-            _this.getMcache();
+            mto = t.mcache.swto;
             _this.mcache.swto = t;
             break;
 
         case MODFlags.shared_ | MODFlags.wildconst:
-            _this.getMcache();
+            mto = t.mcache.swcto;
             _this.mcache.swcto = t;
             break;
 
         case MODFlags.immutable_:
-            _this.getMcache();
+            mto = t.mcache.ito;
             _this.mcache.ito = t;
             break;
 
@@ -524,11 +529,6 @@ void fixTo(Type _this, Type t)
     }
     assert(_this.mod != t.mod);
 
-    if (_this.mod)
-    {
-        _this.getMcache();
-        t.getMcache();
-    }
     switch (_this.mod)
     {
     case 0: