How to detect C++11 support of a compiler with CMake

If you have CMake version 3.1.0 or later you can detect what C++ features
your C++ compiler supports

cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
project(foobar CXX)
message("Your C++ compiler supports these C++ features:")
foreach(i ${CMAKE_CXX_COMPILE_FEATURES})
  message("${i}")
endforeach()

But normally you don’t need to use the CMake variable CMAKE_CXX_COMPILE_FEATURES in your CMake scripts. Instead there are two ways of how to tell CMake under which C++ standard your C++ files should be compiled, either by
specifying the C++ standard explicitly or by specifying the required C++ features and let CMake induce the C++ standard. CMake will make sure the C++ compiler is invoked with the correct command line flags (e.g. -std=c++11).

1. Specifying the C++ standard explicitly

You could specify the C++ standard explicitly, by setting the CMake properties
CXX_STANDARD
and
CXX_STANDARD_REQUIRED for your CMake target.

$ cat /tmp/src/CMakeLists.txt
project(foobar CXX)
cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
add_executable(prog main.cc)
set_property(TARGET prog PROPERTY CXX_STANDARD 11)
set_property(TARGET prog PROPERTY CXX_STANDARD_REQUIRED ON)
$ cat /tmp/src/main.cc
int main() {
  return 0;
}
$ mkdir /tmp/build
$ cd /tmp/build
$ cmake /tmp/src
-- The CXX compiler identification is GNU 4.8.2
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/build
$ make VERBOSE=1 | grep main.cc | grep -- "-c"
/usr/bin/c++    -std=gnu++11 -o CMakeFiles/prog.dir/main.cc.o -c /tmp/src/main.cc
$

2. Specifying the required C++ features and let CMake induce the C++ standard

You could use the CMake command target_compile_features to specify the C++ features that are made use of in your CMake target. From this list CMake will induce the C++ standard to be used. The CMake global property CMAKE_CXX_KNOWN_FEATURES lists the C++ features you can choose from.

cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
message("Your CMake version supports these C++ features:")
get_property(known_features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
foreach(i ${known_features})
  message("${i}")
endforeach()

For example, this C++ program with the filename main.cc makes use of the C++11 features:
cxx_strong_enums, cxx_constexpr, cxx_auto_type

#include <cstdlib>

int main(int argc, char *argv[]) {
  enum class Color { Red, Orange, Yellow, Green, Blue, Violet };
  constexpr float a = 3.1415f;
  auto b = a;
  return EXIT_SUCCESS;
}

This CMakeLists.txt file would build it

cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
project(foobar CXX)
add_executable(foobar main.cc)                                                                                                                                                                                                                                                     
set(needed_features
    cxx_strong_enums
    cxx_constexpr
    cxx_auto_type)
target_compile_features(foobar PRIVATE ${needed_features})