--- a/ast/Exp.d	Thu May 08 10:54:29 2008 +0200
+++ b/ast/Exp.d	Sun May 25 14:40:14 2008 +0200
@@ -27,7 +27,7 @@
     CastExp,
 }
 
-class Exp
+abstract class Exp
 {
     this(ExpType expType, SLoc loc)
     {
@@ -36,7 +36,7 @@
     }
 
     /// Get the type of the expression
-    DType type() { return null; }
+    DType type();
 
     /// Indicates which type the expression is - to avoid a lot of casts
     ExpType expType;
@@ -59,10 +59,8 @@
     /// Get the full extents of the expression
     SourceRange sourceRange() { return SourceRange(loc, loc + 1); }
 
-    Exp simplify()
-    {
-        return this;
-    }
+    /// Do some simplifications
+    Exp simplify() { return this; }
 }
 
 class CallExp : Exp
@@ -284,7 +282,7 @@
     }
 
     override DType type() 
-    { 
+    {
         return exp.type().asPointer.pointerOf; 
     }