ceph/src/seastar/fmt/support/cmake/cxx14.cmake

   1 # C++14 feature support detection
   2
   3 include(CheckCXXSourceCompiles)
   4 include(CheckCXXCompilerFlag)
   5
   6 if (NOT CMAKE_CXX_STANDARD)
   7   set(CMAKE_CXX_STANDARD 11)
   8 endif()
   9 message(STATUS "CXX_STANDARD: ${CMAKE_CXX_STANDARD}")
  10
  11 if (CMAKE_CXX_STANDARD EQUAL 20)
  12   check_cxx_compiler_flag(-std=c++20 has_std_20_flag)
  13   check_cxx_compiler_flag(-std=c++2a has_std_2a_flag)
  14
  15   if (has_std_20_flag)
  16     set(CXX_STANDARD_FLAG -std=c++20)
  17   elseif (has_std_2a_flag)
  18     set(CXX_STANDARD_FLAG -std=c++2a)
  19   endif ()
  20 elseif (CMAKE_CXX_STANDARD EQUAL 17)
  21   check_cxx_compiler_flag(-std=c++17 has_std_17_flag)
  22   check_cxx_compiler_flag(-std=c++1z has_std_1z_flag)
  23
  24   if (has_std_17_flag)
  25     set(CXX_STANDARD_FLAG -std=c++17)
  26   elseif (has_std_1z_flag)
  27     set(CXX_STANDARD_FLAG -std=c++1z)
  28   endif ()
  29 elseif (CMAKE_CXX_STANDARD EQUAL 14)
  30   check_cxx_compiler_flag(-std=c++14 has_std_14_flag)
  31   check_cxx_compiler_flag(-std=c++1y has_std_1y_flag)
  32
  33   if (has_std_14_flag)
  34     set(CXX_STANDARD_FLAG -std=c++14)
  35   elseif (has_std_1y_flag)
  36     set(CXX_STANDARD_FLAG -std=c++1y)
  37   endif ()
  38 elseif (CMAKE_CXX_STANDARD EQUAL 11)
  39   check_cxx_compiler_flag(-std=c++11 has_std_11_flag)
  40   check_cxx_compiler_flag(-std=c++0x has_std_0x_flag)
  41
  42   if (has_std_11_flag)
  43     set(CXX_STANDARD_FLAG -std=c++11)
  44   elseif (has_std_0x_flag)
  45     set(CXX_STANDARD_FLAG -std=c++0x)
  46   endif ()
  47 endif ()
  48
  49 set(CMAKE_REQUIRED_FLAGS ${CXX_STANDARD_FLAG})
  50
  51 # Check if variadic templates are working and not affected by GCC bug 39653:
  52 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39653
  53 check_cxx_source_compiles("
  54   template <class T, class ...Types>
  55   struct S { typedef typename S<Types...>::type type; };
  56   int main() {}" SUPPORTS_VARIADIC_TEMPLATES)
  57 if (NOT SUPPORTS_VARIADIC_TEMPLATES)
  58   set (SUPPORTS_VARIADIC_TEMPLATES OFF)
  59 endif ()
  60
  61 # Check if initializer lists are supported.
  62 check_cxx_source_compiles("
  63   #include <initializer_list>
  64   int main() {}" SUPPORTS_INITIALIZER_LIST)
  65 if (NOT SUPPORTS_INITIALIZER_LIST)
  66   set (SUPPORTS_INITIALIZER_LIST OFF)
  67 endif ()
  68
  69 # Check if enum bases are available
  70 check_cxx_source_compiles("
  71   enum C : char {A};
  72   int main() {}"
  73   SUPPORTS_ENUM_BASE)
  74 if (NOT SUPPORTS_ENUM_BASE)
  75   set (SUPPORTS_ENUM_BASE OFF)
  76 endif ()
  77
  78 # Check if type traits are available
  79 check_cxx_source_compiles("
  80   #include <type_traits>
  81   class C { void operator=(const C&); };
  82   int main() { static_assert(!std::is_copy_assignable<C>::value, \"\"); }"
  83   SUPPORTS_TYPE_TRAITS)
  84 if (NOT SUPPORTS_TYPE_TRAITS)
  85   set (SUPPORTS_TYPE_TRAITS OFF)
  86 endif ()
  87
  88 # Check if user-defined literals are available
  89 check_cxx_source_compiles("
  90   void operator\"\" _udl(long double);
  91   int main() {}"
  92   SUPPORTS_USER_DEFINED_LITERALS)
  93 if (NOT SUPPORTS_USER_DEFINED_LITERALS)
  94   set (SUPPORTS_USER_DEFINED_LITERALS OFF)
  95 endif ()
  96
  97 set(CMAKE_REQUIRED_FLAGS )