From 60b59217359ecac2060637906e9eae14216a47d7 Mon Sep 17 00:00:00 2001
From: Billy Robert O'Neal III <bion@microsoft.com>
Date: Wed, 27 Apr 2016 18:44:39 -0700
Subject: [PATCH] Remove redundant MSVC++ /W3 triggering warnings

This change looks for CMake's default setting for MSVC++, /W3 (and any
other level should that change in the future), and removes it before
adding /W4. This stops the build for MSVC++ emitting warnings about
/W4 overriding /W3 earlier on the command line.
---
 CMakeLists.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c722526..59405610 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,7 +33,8 @@ include(CXXFeatureCheck)
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
   # Turn compiler warnings up to 11
-  add_cxx_compiler_flag(-W4)
+  string(REGEX REPLACE "[-/]W[1-4]" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 
   # Link time optimisation