From 62d1695632ac9cc17ca9bcb7428f2d01fe16d9da Mon Sep 17 00:00:00 2001
From: Joseph Poirier <jdpoirier@gmail.com>
Date: Sun, 14 Jun 2015 17:03:55 -0500
Subject: [PATCH] Fixes issue #5

---
 expression.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/expression.c b/expression.c
index 5a3d847..502e987 100644
--- a/expression.c
+++ b/expression.c
@@ -755,7 +755,7 @@ void ExpressionPrefixOperator(struct ParseState *Parser,
             int Size = TypeSize(TopValue->Typ->FromType, 0, true);
             struct Value *StackValue;
             void *ResultPtr;
-            if (TopValue->Val->Pointer == NULL)
+            if (Op != TokenUnaryNot && TopValue->Val->Pointer == NULL)
                 ProgramFail(Parser, "a. invalid use of a NULL pointer");
             if (!TopValue->IsLValue)
                 ProgramFail(Parser, "can't assign to this");
@@ -768,6 +768,10 @@ void ExpressionPrefixOperator(struct ParseState *Parser,
                 TopValue->Val->Pointer =
                     (void*)((char*)TopValue->Val->Pointer-Size);
                 break;
+            case TokenUnaryNot:
+                TopValue->Val->Pointer =
+                    (void*)((char*)(!TopValue->Val->Pointer));
+                break;
             default:
                 ProgramFail(Parser, "invalid operation");
                 break;