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      1 # C++11 feature support detection
      2 
      3 if (NOT FMT_USE_CPP11)
      4   return()
      5 endif ()
      6 
      7 include(CheckCXXCompilerFlag)
      8 
      9 if (FMT_USE_CPP11)
     10   check_cxx_compiler_flag(-std=c++11 HAVE_STD_CPP11_FLAG)
     11   if (HAVE_STD_CPP11_FLAG)
     12     # Check if including cmath works with -std=c++11 and -O3.
     13     # It may not in MinGW due to bug http://ehc.ac/p/mingw/bugs/2250/.
     14     set(CMAKE_REQUIRED_FLAGS "-std=c++11 -O3")
     15     check_cxx_source_compiles("
     16       #include <cmath>
     17       int main() {}" FMT_CPP11_CMATH)
     18     # Check if including <unistd.h> works with -std=c++11.
     19     # It may not in MinGW due to bug http://sourceforge.net/p/mingw/bugs/2024/.
     20     check_cxx_source_compiles("
     21       #include <unistd.h>
     22       int main() {}" FMT_CPP11_UNISTD_H)
     23     if (FMT_CPP11_CMATH AND FMT_CPP11_UNISTD_H)
     24       set(CPP11_FLAG -std=c++11)
     25     else ()
     26       check_cxx_compiler_flag(-std=gnu++11 HAVE_STD_GNUPP11_FLAG)
     27       if (HAVE_STD_CPP11_FLAG)
     28         set(CPP11_FLAG -std=gnu++11)
     29       endif ()
     30     endif ()
     31     set(CMAKE_REQUIRED_FLAGS )
     32   else ()
     33     check_cxx_compiler_flag(-std=c++0x HAVE_STD_CPP0X_FLAG)
     34     if (HAVE_STD_CPP0X_FLAG)
     35       set(CPP11_FLAG -std=c++0x)
     36     endif ()
     37   endif ()
     38 endif ()
     39 
     40 if (CMAKE_CXX_STANDARD)
     41   # Don't use -std compiler flag if CMAKE_CXX_STANDARD is specified.
     42   set(CPP11_FLAG )
     43 endif ()
     44 
     45 set(CMAKE_REQUIRED_FLAGS ${CPP11_FLAG})
     46 
     47 # Check if variadic templates are working and not affected by GCC bug 39653:
     48 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39653
     49 check_cxx_source_compiles("
     50   template <class T, class ...Types>
     51   struct S { typedef typename S<Types...>::type type; };
     52   int main() {}" SUPPORTS_VARIADIC_TEMPLATES)
     53 
     54 # Check if initializer lists are supported.
     55 check_cxx_source_compiles("
     56   #include <initializer_list>
     57   int main() {}" SUPPORTS_INITIALIZER_LIST)
     58 
     59 # Check if enum bases are available
     60 check_cxx_source_compiles("
     61   enum C : char {A};
     62   int main() {}"
     63   SUPPORTS_ENUM_BASE)
     64 
     65 # Check if type traits are available
     66 check_cxx_source_compiles("
     67   #include <type_traits>
     68   class C { void operator=(const C&); };
     69   int main() { static_assert(!std::is_copy_assignable<C>::value, \"\"); }"
     70   SUPPORTS_TYPE_TRAITS)
     71 
     72 # Check if user-defined literals are available
     73 check_cxx_source_compiles("
     74   void operator\"\" _udl(long double);
     75   int main() {}"
     76   SUPPORTS_USER_DEFINED_LITERALS)
     77 
     78 set(CMAKE_REQUIRED_FLAGS )
     79