#.rst:
#
# Adds C++ support.
# Appends EXTRA_CXXFLAGS to CMAKE_CXX_FLAGS.
# If environment variable CXXFLAGS is set, then the CXXFLAGS are used
# and no other flags are used or appended.
#
# Variables used::
#
#   EXTRA_CXXFLAGS
#
# Variables modified::
#
#   CMAKE_CXX_FLAGS
#
# Environment variables used::
#
#   CXXFLAGS
#
# Example autocmake.cfg entry::
#
#   [cxx]
#   source: https://github.com/scisoft/autocmake/raw/master/modules/cxx.cmake
#   docopt: --cxx=<CXX> C++ compiler [default: g++].
#           --extra-cxx-flags=<EXTRA_CXXFLAGS> Extra C++ compiler flags [default: ''].
#   export: 'CXX=%s' % arguments['--cxx']
#   define: '-DEXTRA_CXXFLAGS="%s"' % arguments['--extra-cxx-flags']

enable_language(CXX)

if(NOT DEFINED CMAKE_C_COMPILER_ID)
    message(FATAL_ERROR "CMAKE_C_COMPILER_ID variable is not defined!")
endif()

if(NOT CMAKE_C_COMPILER_WORKS)
    message(FATAL_ERROR "CMAKE_C_COMPILER_WORKS is false!")
endif()

if(DEFINED EXTRA_CXXFLAGS)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXXFLAGS}")
endif()

if(DEFINED ENV{CXXFLAGS})
    message(STATUS "CXXFLAGS is set to '$ENV{CXXFLAGS}'.")
    set(CMAKE_CXX_FLAGS "$ENV{CXXFLAGS}")
endif()