From f6d1c5346fc3b950fe31f7f6f920699e9835cb62 Mon Sep 17 00:00:00 2001
From: Sebastien Braun
Date: Sun, 10 Oct 2010 14:31:25 +0200
Subject: Fix bug in logical OR when chaining Require<...> Policy.

---
 src/input/inputEventHandler.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/input/inputEventHandler.h b/src/input/inputEventHandler.h
index 3879b80..11e2f4e 100644
--- a/src/input/inputEventHandler.h
+++ b/src/input/inputEventHandler.h
@@ -102,8 +102,10 @@ template<IMPLICIT_TYPE_LIST_PARAMS(Trait)>
 BEGIN_POLICY_CLASS(Require)
 {
 	static const bool areSystemRequirementsFulfilled =
-			NextPolicy::areSystemRequirementsFulfilled ||
-			detail::Matches<AllOf<IMPLICIT_TYPE_LIST_ARGS(Trait)>, detail::SystemTraits>::value;
+			(NextPolicy::areSystemRequirementsFulfilled
+				&& !NextPolicy::areSystemRequirementsVacuouslyFulfilled)
+			|| detail::Matches<AllOf<IMPLICIT_TYPE_LIST_ARGS(Trait)>, detail::SystemTraits>::value;
+	static const bool areSystemRequirementsVacuouslyFulfilled = false;
 }
 END_POLICY_CLASS
 
@@ -158,6 +160,9 @@ struct InputEventHandlerPolicyBase
 	// everywhere
 	static const bool areSystemRequirementsFulfilled = true;
 
+	// We need this to implement proper logical OR
+	static const bool areSystemRequirementsVacuouslyFulfilled = true;
+
 	// Generate an error when no match policy is given.
 	bool isApplicable(InputEvent const&)
 	{
-- 
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