both command line arg and env var NGRAPH_WARNINGS_AS_ERRORS (#558)

* add support for both command line arg and env var to set NGRAPH_WARINGS_AS_ERRORS'

CMakeLists.txt

@@ -60,6 +60,8 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 # set directory where the custom finders live
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/Modules/")
 
+include(var_functions)
+
 #-----------------------------------------------------------------------------------------------
 # Installation logic...
 #-----------------------------------------------------------------------------------------------
@@ -97,11 +99,11 @@ endif()
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")
-if(DEFINED ENV{NGRAPH_WARNINGS_AS_ERRORS})
-    if($ENV{NGRAPH_WARNINGS_AS_ERRORS})
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
-        message(STATUS "Warnings as errors")
-    endif()
+
+ngraph_var(NGRAPH_WARNINGS_AS_ERRORS DEFAULT "OFF")
+if ("${NGRAPH_WARNINGS_AS_ERRORS}" MATCHES "^(ON|TRUE)$")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
+    message(STATUS "Warnings as errors")
 endif()
 SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3 -g")
 SET(CMAKE_CXX_FLAGS_RELEASE "-O3")

cmake/Modules/var_functions.cmake

+# ******************************************************************************
+# Copyright 2017-2018 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ******************************************************************************
+
+# function check existence of cmake and environment variable and read their value
+# If the variable is not defined then the supplied default value used
+# example:
+#    ngraph_var(NGRAPH_VARIABLE_NAME DEFAULT "OFF")
+#        checks if variable NGRAPH_VARIABLE_NAME was passed in via the cmake command line
+#            if found then passed in value is used
+#            else checks for the existence of the environment variable NGRAPH_VARIABLE_NAME
+#                if found it's value is used
+#        if none of the above then the default value is used
+function(NGRAPH_VAR)
+    set(options)
+    set(oneValueArgs DEFAULT)
+    set(multiValueArgs)
+    cmake_parse_arguments(NGRAPH_VAR "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+    if (NOT DEFINED ${NGRAPH_VAR_UNPARSED_ARGUMENTS})
+        set(${NGRAPH_VAR_UNPARSED_ARGUMENTS} ${NGRAPH_VAR_DEFAULT} PARENT_SCOPE)
+        if(DEFINED ENV{${NGRAPH_VAR_UNPARSED_ARGUMENTS}})
+            set(${NGRAPH_VAR_UNPARSED_ARGUMENTS} $ENV{${NGRAPH_VAR_UNPARSED_ARGUMENTS}} PARENT_SCOPE)
+        endif()
+    endif()
+endfunction()