Revert "Improvements to CMake buildsystem (#563)"

This reverts commit 3e33bb31.

The original commit broke the build (#612) when yaml-cpp is used as a git submodule.

CMakeLists.txt

 ###
 ### CMake settings
 ###
+## Due to Mac OSX we need to keep compatibility with CMake 2.6
 # see http://www.cmake.org/Wiki/CMake_Policies
-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 2.6)
+# see http://www.cmake.org/cmake/help/cmake-2-8-docs.html#policy:CMP0012
+if(POLICY CMP0012)
+	cmake_policy(SET CMP0012 OLD)
+endif()
+# see http://www.cmake.org/cmake/help/cmake-2-8-docs.html#policy:CMP0015
+if(POLICY CMP0015)
+	cmake_policy(SET CMP0015 OLD)
+endif()
+# see https://cmake.org/cmake/help/latest/policy/CMP0042.html
+if(POLICY CMP0042)
+	# Enable MACOSX_RPATH by default.
+	cmake_policy(SET CMP0042 NEW)
+endif()
 
 include(CheckCXXCompilerFlag)
 
+
 ###
 ### Project settings
 ###
@@ -16,6 +31,8 @@ set(YAML_CPP_VERSION_MINOR "6")
 set(YAML_CPP_VERSION_PATCH "2")
 set(YAML_CPP_VERSION "${YAML_CPP_VERSION_MAJOR}.${YAML_CPP_VERSION_MINOR}.${YAML_CPP_VERSION_PATCH}")
 
+enable_testing()
+
 
 ###
 ### Project options
@@ -31,10 +48,6 @@ option(YAML_CPP_BUILD_CONTRIB "Enable contrib stuff in library" ON)
 #     http://www.cmake.org/cmake/help/cmake2.6docs.html#command:add_library
 option(BUILD_SHARED_LIBS "Build Shared Libraries" OFF)
 
-# Set minimum C++ to 2011 standards
-set(CMAKE_CXX_STANDARD 11)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-
 # --> Apple
 option(APPLE_UNIVERSAL_BIN "Apple: Build universal binary" OFF)
 
@@ -175,7 +188,7 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR
 		set(GCC_EXTRA_OPTIONS "${GCC_EXTRA_OPTIONS} ${FLAG_TESTED}")
 	endif()
 	#
-	set(yaml_cxx_flags "-Wall ${GCC_EXTRA_OPTIONS} -pedantic -Wno-long-long ${yaml_cxx_flags}")
+	set(yaml_cxx_flags "-Wall ${GCC_EXTRA_OPTIONS} -pedantic -Wno-long-long -std=c++11 ${yaml_cxx_flags}")
 
 	### Make specific
 	if(${CMAKE_BUILD_TOOL} MATCHES make OR ${CMAKE_BUILD_TOOL} MATCHES gmake)
@@ -347,7 +360,6 @@ endif()
 ### Extras
 ###
 if(YAML_CPP_BUILD_TESTS)
-	enable_testing()
 	add_subdirectory(test)
 endif()
 if(YAML_CPP_BUILD_TOOLS)

test/CMakeLists.txt

-include(ExternalProject)
-
-if(MSVC)
-    # MS Visual Studio expects lib prefix on static libraries,
-    # but CMake compiles them without prefix
-    # See https://gitlab.kitware.com/cmake/cmake/issues/17338
-    set(CMAKE_STATIC_LIBRARY_PREFIX "")
+set(gtest_force_shared_crt ${MSVC_SHARED_RT} CACHE BOOL
+  "Use shared (DLL) run-time lib even when Google Test built as a static lib.")
+add_subdirectory(gtest-1.8.0)
+include_directories(SYSTEM gtest-1.8.0/googlemock/include)
+include_directories(SYSTEM gtest-1.8.0/googletest/include)
+
+if(WIN32 AND BUILD_SHARED_LIBS)
+  add_definitions("-DGTEST_LINKED_AS_SHARED_LIBRARY")
 endif()
 
-ExternalProject_Add(
-	googletest_project
-	SOURCE_DIR "${CMAKE_SOURCE_DIR}/test/gtest-1.8.0"
-	INSTALL_DIR "${CMAKE_BINARY_DIR}/prefix"
-	CMAKE_ARGS
-		-DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
-		-DBUILD_GMOCK=ON
-		-Dgtest_force_shared_crt=ON
-)
-
-add_library(gmock UNKNOWN IMPORTED)
-set_target_properties(gmock PROPERTIES
-    IMPORTED_LOCATION
-    ${PROJECT_BINARY_DIR}/prefix/lib/${CMAKE_STATIC_LIBRARY_PREFIX}gmock${CMAKE_STATIC_LIBRARY_SUFFIX}
-)
-
-find_package(Threads)
-
-include_directories(SYSTEM "${PROJECT_BINARY_DIR}/prefix/include")
-
 if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR
    CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   set(yaml_test_flags "-Wno-variadic-macros -Wno-sign-compare")
@@ -34,6 +15,12 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR
   if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     set(yaml_test_flags "${yaml_test_flags} -Wno-c99-extensions")
   endif()
+
+  if(CMAKE_COMPILER_IS_GNUCXX)
+    set(yaml_test_flags "${yaml_test_flags} -std=gnu++11")
+  else()
+    set(yaml_test_flags "${yaml_test_flags} -std=c++11")
+  endif()
 endif()
 
 file(GLOB test_headers [a-z_]*.h)
@@ -50,15 +37,9 @@ add_executable(run-tests
 	${test_sources}
 	${test_headers}
 )
-
-add_dependencies(run-tests googletest_project)
-
 set_target_properties(run-tests PROPERTIES
   COMPILE_FLAGS "${yaml_c_flags} ${yaml_cxx_flags} ${yaml_test_flags}"
 )
-target_link_libraries(run-tests
-    yaml-cpp
-    gmock
-    ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries(run-tests yaml-cpp gmock)
 
 add_test(yaml-test ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/run-tests)

util/CMakeLists.txt

@@ -3,12 +3,14 @@ cmake_minimum_required(VERSION 3.5)
 add_sources(parse.cpp)
 add_executable(parse parse.cpp)
 target_link_libraries(parse yaml-cpp)
+set_target_properties(parse PROPERTIES COMPILE_FLAGS "-std=c++11")
 
 add_sources(sandbox.cpp)
 add_executable(sandbox sandbox.cpp)
 target_link_libraries(sandbox yaml-cpp)
+set_target_properties(sandbox PROPERTIES COMPILE_FLAGS "-std=c++11")
 
 add_sources(read.cpp)
 add_executable(read read.cpp)
 target_link_libraries(read yaml-cpp)
-
+set_target_properties(read PROPERTIES COMPILE_FLAGS "-std=c++11")