Modernize the way to set c++ standard

.travis.yml

@@ -5,15 +5,11 @@ matrix:
   include:
     # Note that we stick some additional variations to some builds
     - compiler: gcc
-      env: CXXSTD=c++11 BUILD_COVERAGE=yes
-    - compiler: gcc
-      env: CXXSTD=c++1y
+      env: BUILD_COVERAGE=yes
     - compiler: clang
-      env: CXXSTD=c++11
+      env: BUILD_NOOPTLIBS=yes
     - compiler: clang
-      env: CXXSTD=c++1y BUILD_NOOPTLIBS=yes
-    - compiler: clang
-      env: CXXSTD=c++1y BUILD_STATIC=yes
+      env: BUILD_STATIC=yes
 before_install:
   - sudo add-apt-repository --yes ppa:zoogie/sdl2-snapshots
   - sudo apt-get update -qq
@@ -43,7 +39,7 @@ before_install:
 
 script:
   - export PREFIX=`pwd`.prefix
-  - cmake . -DCMAKE_INSTALL_PREFIX=${PREFIX} -DSDL2PP_WITH_WERROR=YES -DSDL2PP_CXXSTD=${CXXSTD} ${CMAKE_EXTRA_ARGS}
+  - cmake . -DCMAKE_INSTALL_PREFIX=${PREFIX} -DSDL2PP_WITH_WERROR=YES ${CMAKE_EXTRA_ARGS}
   - VERBOSE=1 make && make ARGS=-V test && make install
   - cppcheck -I . --enable=performance,portability,information,missingInclude --error-exitcode=2 SDL2pp # `style' gives false positive in cppcheck 1.61 which comes with trusty
   - make doxygen

CMakeLists.txt

@@ -11,12 +11,14 @@ set(SDL2PP_PATCH_VERSION 0)
 
 set(SDL2PP_VERSION "${SDL2PP_MAJOR_VERSION}.${SDL2PP_MINOR_VERSION}.${SDL2PP_PATCH_VERSION}")
 
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED YES)
+set(CMAKE_CXX_EXTENSIONS NO)
+
 # there are functions present on wiki, but not yet in stable SDL2 releases;
 # we hide these under following options
 option(SDL2PP_WITH_WERROR "Make warnings fatal" OFF)
 
-set(SDL2PP_CXXSTD "c++11" CACHE STRING "Used c++ standard")
-
 if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
 	OPTION(SDL2PP_WITH_IMAGE "Enable SDL2_image support" ON)
 	OPTION(SDL2PP_WITH_TTF "Enable SDL2_ttf support" ON)
@@ -75,7 +77,6 @@ else()
 	set(CMAKE_EXE_LINKER_FLAGS_COVERAGE "${CMAKE_EXE_LINKER_FLAGS_DEBUG} --coverage")
 	set(CMAKE_SHARED_LINKER_FLAGS_COVERAGE "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} --coverage")
 
-	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=${SDL2PP_CXXSTD}")
 	set(SDL2PP_WARNINGS "${SDL2PP_WARNINGS} -Wall -Wextra -pedantic")
 	set(SDL2PP_WERROR_FLAG "-Werror")