add support for CFLAGS and CXXFLAGS; fixes #1

modules/cxx.cmake

@@ -1,13 +1,46 @@
+#.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_CXX_COMPILER_ID)
-    message(FATAL_ERROR "CMAKE_CXX_COMPILER_ID variable is not defined!")
+if(NOT DEFINED CMAKE_C_COMPILER_ID)
+    message(FATAL_ERROR "CMAKE_C_COMPILER_ID variable is not defined!")
 endif()
 
-if(NOT CMAKE_CXX_COMPILER_WORKS)
-    message(FATAL_ERROR "CMAKE_CXX_COMPILER_WORKS is false!")
+if(NOT CMAKE_C_COMPILER_WORKS)
+    message(FATAL_ERROR "CMAKE_C_COMPILER_WORKS is false!")
 endif()
 
-if(DEFINED EXTRA_CXX_FLAGS)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXX_FLAGS}")
+if(DEFINED EXTRA_CXXFLAGS)
+    set(CMAKE_CXX_FLAGS "${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()