1# - Compile and run code to check for C++ features
2#
3# This functions compiles a source file under the `cmake` folder
4# and adds the corresponding `HAVE_[FILENAME]` flag to the CMake
5# environment
6#
7#  cxx_feature_check(<FLAG> [<VARIANT>])
8#
9# - Example
10#
11# include(CXXFeatureCheck)
12# cxx_feature_check(STD_REGEX)
13# Requires CMake 2.6+
14
15if(__cxx_feature_check)
16  return()
17endif()
18set(__cxx_feature_check INCLUDED)
19
20function(cxx_feature_check FILE)
21  string(TOLOWER ${FILE} FILE)
22  string(TOUPPER ${FILE} VAR)
23  string(TOUPPER "HAVE_${VAR}" FEATURE)
24  if (DEFINED HAVE_${VAR})
25    return()
26  endif()
27  message("-- Performing Test ${FEATURE}")
28  try_run(RUN_${FEATURE} COMPILE_${FEATURE}
29          ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/${FILE}.cpp
30          CMAKE_FLAGS ${BENCHMARK_CXX_LINKER_FLAGS}
31          LINK_LIBRARIES ${BENCHMARK_CXX_LIBRARIES})
32  if(RUN_${FEATURE} EQUAL 0)
33    message("-- Performing Test ${FEATURE} -- success")
34    set(HAVE_${VAR} 1 CACHE INTERNAL "Feature test for ${FILE}" PARENT_SCOPE)
35    add_definitions(-DHAVE_${VAR})
36  else()
37    if(NOT COMPILE_${FEATURE})
38      message("-- Performing Test ${FEATURE} -- failed to compile")
39    else()
40      message("-- Performing Test ${FEATURE} -- compiled but failed to run")
41    endif()
42  endif()
43endfunction()
44
45