CTFE: Support 'with', fix for 'super'

With statements are simple, but exposed a bug in CTFE super:
calls to 'super' shouldn't use the vtable of the original class.

src/interpret.c

@@ -1575,8 +1575,18 @@ Expression *WithStatement::interpret(InterState *istate)
     printf("WithStatement::interpret()\n");
 #endif
     START()
-    error("with statements are not yet supported in CTFE");
-    return EXP_CANT_INTERPRET;
+    Expression *e = exp->interpret(istate);
+    if (exceptionOrCantInterpret(e))
+        return e;
+    if (wthis->type->ty == Tpointer && exp->type->ty != Tpointer)
+    {
+        e = new AddrExp(loc, e);
+        e->type = wthis->type;
+    }
+    wthis->createStackValue(e);
+    e = body ? body->interpret(istate) : EXP_VOID_INTERPRET;
+    wthis->setValueNull();
+    return e;
 }
 
 Expression *AsmStatement::interpret(InterState *istate)
@@ -4648,6 +4658,7 @@ Expression *CallExp::interpret(InterState *istate, CtfeGoal goal)
             if (exceptionOrCantInterpret(pthis))
                 return pthis;
                 // Evaluate 'this'
+            Expression *oldpthis = pthis;
             if (pthis->op != TOKvar)
                 pthis = pthis->interpret(istate, ctfeNeedLvalue);
             if (exceptionOrCantInterpret(pthis))
@@ -4659,14 +4670,22 @@ Expression *CallExp::interpret(InterState *istate, CtfeGoal goal)
                 {   assert(((VarExp*)thisval)->var->isVarDeclaration());
                     thisval = ((VarExp*)thisval)->var->isVarDeclaration()->getValue();
                 }
+                // Get the function from the vtable of the original class
+                ClassDeclaration *cd;
                 if (thisval && thisval->op == TOKnull)
                 {
                     error("function call through null class reference %s", pthis->toChars());
                     return EXP_CANT_INTERPRET;
                 }
-                // Get the function from the vtable of the original class
-                assert(thisval && thisval->op == TOKclassreference);
-                ClassDeclaration *cd = ((ClassReferenceExp *)thisval)->originalClass();
+                if (oldpthis->op == TOKsuper)
+                {   assert(oldpthis->type->ty == Tclass);
+                    cd = ((TypeClass *)oldpthis->type)->sym;
+                }
+                else
+                {
+                    assert(thisval && thisval->op == TOKclassreference);
+                    cd = ((ClassReferenceExp *)thisval)->originalClass();
+                }
                 // We can't just use the vtable index to look it up, because
                 // vtables for interfaces don't get populated until the glue layer.
                 fd = cd->findFunc(fd->ident, (TypeFunction *)fd->type);