From 0b5d6d7880bd6595571e0b556f72f84ba300343b Mon Sep 17 00:00:00 2001
From: Jacco Geul <jacco@geul.net>
Date: Thu, 14 Sep 2017 11:36:41 +0200
Subject: [PATCH] Variable cleaning fix for Mac OS X bug.

---
 external/CMake/add_boost.cmake | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/external/CMake/add_boost.cmake b/external/CMake/add_boost.cmake
index a54e2be9d..a1d75c352 100755
--- a/external/CMake/add_boost.cmake
+++ b/external/CMake/add_boost.cmake
@@ -108,9 +108,14 @@ foreach(Component ${BoostComponents})
     set(BoostComponentsDir OFF)
   endif()
   
-  # Need to unset these too, otherwise other find_package calls willl not update them.
-  unset("${Boost_${ComponentUpper}_FOUND}" CACHE)
-  unset("${Boost_${ComponentUpper}_LIBRARY}" CACHE)
+  # Need to unset these too, otherwise other find_package calls willl not update them. Also some are put in current scope and cache
+  unset("Boost_${ComponentUpper}_FOUND")
+  unset("Boost_${ComponentUpper}_LIBRARY")
+  unset("Boost_${ComponentUpper}_FOUND" CACHE)
+  unset("Boost_${ComponentUpper}_LIBRARY" CACHE)
+  unset("Boost_${ComponentUpper}_LIBRARIES")
+  unset("Boost_${ComponentUpper}_LIBRARY_DEBUG" CACHE)
+  unset("Boost_${ComponentUpper}_LIBRARY_RELEASE" CACHE)
   
   # Exit the for loop if a single component fails
   if(NOT ${BoostComponentsDir})
@@ -123,17 +128,19 @@ foreach(Component ${BoostComponents})
 endforeach()
 
 # Unset all variable from find_package(Boost), preventing future usages of this macro becoming lazy.
-unset(Boost_FOUND CACHE)
-unset(Boost_INCLUDE_DIRS CACHE)
+# As before some variables are also cached, so need double cleaning
+unset(Boost_FOUND)
+unset(Boost_INCLUDE_DIRS)
+unset(Boost_LIBRARY_DIRS)
 unset(Boost_LIBRARY_DIRS CACHE)
-unset(Boost_LIBRARIES CACHE)
+unset(Boost_LIBRARIES)
+unset(Boost_VERSION)
 unset(Boost_VERSION CACHE)
+unset(Boost_LIB_VERSION)
 unset(Boost_LIB_VERSION CACHE)
-unset(Boost_MAJOR_VERSION CACHE)
-unset(Boost_MINOR_VERSION CACHE)
-unset(Boost_SUBMINOR_VERSION CACHE)
-unset(Boost_LIB_DIAGNOSTIC_DEFINITIONS CACHE)
-endif()
+unset(Boost_MAJOR_VERSION)
+unset(Boost_MINOR_VERSION)
+unset(Boost_SUBMINOR_VERSION)
 
 # Check if all components were found and if their location is local and not on the system.
 if(${BoostComponentsFound} AND ${BoostComponentsDir})