outlined the compiler feature tests to improve script readability

CMakeLists.txt

@@ -23,39 +23,12 @@ message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")
 
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 
-include(CheckCXXCompilerFlag)
-check_cxx_compiler_flag(-std=c++11 HAVE_STD_CPP11_FLAG)
-if (HAVE_STD_CPP11_FLAG)
-  # Check if including cmath works with -std=c++11 and -O3.
-  # It may not in MinGW due to bug http://ehc.ac/p/mingw/bugs/2250/.
-  set(CMAKE_REQUIRED_FLAGS "-std=c++11 -O3")
-  check_cxx_source_compiles("
-    #include <cmath>
-    int main() {}" FMT_CPP11_CMATH)
-  # Check if including <unistd.h> works with -std=c++11.
-  # It may not in MinGW due to bug http://sourceforge.net/p/mingw/bugs/2024/.
-  check_cxx_source_compiles("
-    #include <unistd.h>
-    int main() {}" FMT_CPP11_UNISTD_H)
-  if (FMT_CPP11_CMATH AND FMT_CPP11_UNISTD_H)
-    set(CPP11_FLAG -std=c++11)
-  else ()
-    check_cxx_compiler_flag(-std=gnu++11 HAVE_STD_GNUPP11_FLAG)
-    if (HAVE_STD_CPP11_FLAG)
-      set(CPP11_FLAG -std=gnu++11)
-    endif ()
-  endif ()
-  set(CMAKE_REQUIRED_FLAGS )
-else ()
-  check_cxx_compiler_flag(-std=c++0x HAVE_STD_CPP0X_FLAG)
-  if (HAVE_STD_CPP0X_FLAG)
-    set(CPP11_FLAG -std=c++0x)
-  endif ()
-endif ()
 
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH}
   "${CMAKE_CURRENT_SOURCE_DIR}/support/cmake")
 
+include(testCxx11)
+
 if (CMAKE_GENERATOR MATCHES "Visual Studio")
   # If Microsoft SDK is installed create script run-msbuild.bat that
   # calls SetEnv.cmd to to set up build environment and runs msbuild.

support/cmake/testCxx11.cmake

@@ -0,0 +1,58 @@
+include(CheckCXXCompilerFlag)
+
+check_cxx_compiler_flag(-std=c++11 HAVE_STD_CPP11_FLAG)
+if (HAVE_STD_CPP11_FLAG)
+  # Check if including cmath works with -std=c++11 and -O3.
+  # It may not in MinGW due to bug http://ehc.ac/p/mingw/bugs/2250/.
+  set(CMAKE_REQUIRED_FLAGS "-std=c++11 -O3")
+  check_cxx_source_compiles("
+    #include <cmath>
+    int main() {}" FMT_CPP11_CMATH)
+  # Check if including <unistd.h> works with -std=c++11.
+  # It may not in MinGW due to bug http://sourceforge.net/p/mingw/bugs/2024/.
+  check_cxx_source_compiles("
+    #include <unistd.h>
+    int main() {}" FMT_CPP11_UNISTD_H)
+  if (FMT_CPP11_CMATH AND FMT_CPP11_UNISTD_H)
+    set(CPP11_FLAG -std=c++11)
+  else ()
+    check_cxx_compiler_flag(-std=gnu++11 HAVE_STD_GNUPP11_FLAG)
+    if (HAVE_STD_CPP11_FLAG)
+      set(CPP11_FLAG -std=gnu++11)
+    endif ()
+  endif ()
+  set(CMAKE_REQUIRED_FLAGS )
+else ()
+  check_cxx_compiler_flag(-std=c++0x HAVE_STD_CPP0X_FLAG)
+  if (HAVE_STD_CPP0X_FLAG)
+    set(CPP11_FLAG -std=c++0x)
+  endif ()
+endif ()
+
+
+set(CMAKE_REQUIRED_FLAGS ${CPP11_FLAG})
+# Check if variadic templates are working and not affected by GCC bug 39653:
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39653
+check_cxx_source_compiles("
+  template <class T, class ...Types>
+  struct S { typedef typename S<Types...>::type type; };
+  int main() {}" SUPPORTS_VARIADIC_TEMPLATES)
+
+# Check if initializer lists are supported.
+check_cxx_source_compiles("
+  #include <initializer_list>
+  int main() {}" SUPPORTS_INITIALIZER_LIST)
+
+# Check if enum bases are available
+check_cxx_source_compiles("
+  enum C : char {A};
+  int main() {}"
+  SUPPORTS_ENUM_BASE)
+
+# Check if type traits are available
+check_cxx_source_compiles("
+  #include <type_traits>
+  class C { void operator=(const C&); };
+  int main() { static_assert(!std::is_copy_assignable<C>::value, \"\"); }"
+  SUPPORTS_TYPE_TRAITS)
+set(CMAKE_REQUIRED_FLAGS )

test/CMakeLists.txt

@@ -28,18 +28,8 @@ endif ()
 
 # Check if variadic templates are working and not affected by GCC bug 39653:
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39653
-check_cxx_source_compiles("
+if (NOT SUPPORTS_VARIADIC_TEMPLATES OR NOT SUPPORTS_INITIALIZER_LIST)
-  template <class T, class ...Types>
+  target_compile_definitions(gmock PUBLIC GTEST_LANG_CXX11=0)
-  struct S { typedef typename S<Types...>::type type; };
-  int main() {}" FMT_VARIADIC_TEMPLATES)
-
-# Check if initializer lists are supported.
-check_cxx_source_compiles("
-  #include <initializer_list>
-  int main() {}" FMT_INITIALIZER_LIST)
-
-if (NOT FMT_VARIADIC_TEMPLATES OR NOT FMT_INITIALIZER_LIST)
-  add_definitions(-DGTEST_LANG_CXX11=0)
 endif ()
 
 # Workaround a bug in implementation of variadic templates in MSVC11.
@@ -91,11 +81,7 @@ if (CPP11_FLAG)
   set_target_properties(util-test PROPERTIES COMPILE_FLAGS ${CPP11_FLAG})
 endif ()
 
-check_cxx_source_compiles("
+if (SUPPORTS_ENUM_BASE)
-  enum C : char {A};
-  int main() {}"
-  HAVE_ENUM_BASE)
-if (HAVE_ENUM_BASE)
   set_target_properties(util-test
     PROPERTIES COMPILE_DEFINITIONS "FMT_USE_ENUM_BASE=1")
 endif ()
@@ -104,12 +90,7 @@ foreach (src ${FMT_SOURCES})
   set(FMT_TEST_SOURCES ${FMT_TEST_SOURCES} ../${src})
 endforeach ()
 
-check_cxx_source_compiles("
+if (SUPPORTS_TYPE_TRAITS)
-  #include <type_traits>
-  class C { void operator=(const C&); };
-  int main() { static_assert(!std::is_copy_assignable<C>::value, \"\"); }"
-  HAVE_TYPE_TRAITS)
-if (HAVE_TYPE_TRAITS)
   foreach (target format-test util-test)
     set_target_properties(${target}
       PROPERTIES COMPILE_DEFINITIONS "FMT_USE_TYPE_TRAITS=1")