init repo.

third_party/benchmark/cmake/CXXFeatureCheck.cmake

@@ -0,0 +1,82 @@
+# - Compile and run code to check for C++ features
+#
+# This functions compiles a source file under the `cmake` folder
+# and adds the corresponding `HAVE_[FILENAME]` flag to the CMake
+# environment
+#
+#  cxx_feature_check(<FLAG> [<VARIANT>])
+#
+# - Example
+#
+# include(CXXFeatureCheck)
+# cxx_feature_check(STD_REGEX)
+# Requires CMake 2.8.12+
+
+if(__cxx_feature_check)
+  return()
+endif()
+set(__cxx_feature_check INCLUDED)
+
+option(CXXFEATURECHECK_DEBUG OFF)
+
+function(cxx_feature_check FILE)
+  string(TOLOWER ${FILE} FILE)
+  string(TOUPPER ${FILE} VAR)
+  string(TOUPPER "HAVE_${VAR}" FEATURE)
+  if (DEFINED HAVE_${VAR})
+    set(HAVE_${VAR} 1 PARENT_SCOPE)
+    add_definitions(-DHAVE_${VAR})
+    return()
+  endif()
+
+  set(FEATURE_CHECK_CMAKE_FLAGS ${BENCHMARK_CXX_LINKER_FLAGS})
+  if (ARGC GREATER 1)
+    message(STATUS "Enabling additional flags: ${ARGV1}")
+    list(APPEND FEATURE_CHECK_CMAKE_FLAGS ${ARGV1})
+  endif()
+
+  if (NOT DEFINED COMPILE_${FEATURE})
+    if(CMAKE_CROSSCOMPILING)
+      message(STATUS "Cross-compiling to test ${FEATURE}")
+      try_compile(COMPILE_${FEATURE}
+              ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp
+              CXX_STANDARD 11
+              CXX_STANDARD_REQUIRED ON
+              CMAKE_FLAGS ${FEATURE_CHECK_CMAKE_FLAGS}
+              LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}
+              OUTPUT_VARIABLE COMPILE_OUTPUT_VAR)
+      if(COMPILE_${FEATURE})
+        message(WARNING
+              "If you see build failures due to cross compilation, try setting HAVE_${VAR} to 0")
+        set(RUN_${FEATURE} 0 CACHE INTERNAL "")
+      else()
+        set(RUN_${FEATURE} 1 CACHE INTERNAL "")
+      endif()
+    else()
+      message(STATUS "Compiling and running to test ${FEATURE}")
+      try_run(RUN_${FEATURE} COMPILE_${FEATURE}
+              ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp
+              CXX_STANDARD 11
+              CXX_STANDARD_REQUIRED ON
+              CMAKE_FLAGS ${FEATURE_CHECK_CMAKE_FLAGS}
+              LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES}
+              COMPILE_OUTPUT_VARIABLE COMPILE_OUTPUT_VAR)
+    endif()
+  endif()
+
+  if(RUN_${FEATURE} EQUAL 0)
+    message(STATUS "Performing Test ${FEATURE} -- success")
+    set(HAVE_${VAR} 1 PARENT_SCOPE)
+    add_definitions(-DHAVE_${VAR})
+  else()
+    if(NOT COMPILE_${FEATURE})
+      if(CXXFEATURECHECK_DEBUG)
+        message(STATUS "Performing Test ${FEATURE} -- failed to compile: ${COMPILE_OUTPUT_VAR}")
+      else()
+        message(STATUS "Performing Test ${FEATURE} -- failed to compile")
+      endif()
+    else()
+      message(STATUS "Performing Test ${FEATURE} -- compiled but failed to run")
+    endif()
+  endif()
+endfunction()