Correct CMake Logic and update cpplint to Python3 (gazebosim#117)

* Update cpplint to python3 compatible-version
* Find and use Python3 if available
* Split targets but maintain codecheck
* Add Ignition-specific default filters and suppressions

Co-authored-by: Louise Poubel <louise@openrobotics.org>
Signed-off-by: Michael Carroll <michael@openrobotics.org>

cmake/IgnCodeCheck.cmake

@@ -1,20 +1,15 @@
 # Setup the codecheck target, which will run cppcheck and cppplint.
 function(ign_setup_target_for_codecheck)
+  include(IgnPython)
 
   find_program(CPPCHECK_PATH cppcheck)
-  find_program(PYTHON_PATH python)
   find_program(FIND_PATH find)
 
   if(NOT CPPCHECK_PATH)
     message(STATUS "The program [cppcheck] was not found! Skipping codecheck setup")
     return()
   endif()
 
-  if(NOT PYTHON_PATH)
-    message(STATUS "python not found! Skipping codecheck setup.")
-    return()
-  endif()
-
   if(NOT FIND_PATH)
     message(STATUS "The program [find] was not found! Skipping codecheck setup.")
     return()
@@ -37,17 +32,20 @@ function(ign_setup_target_for_codecheck)
 
   message(STATUS "Adding codecheck target")
 
-  # Setup the codecheck target
-  add_custom_target(codecheck
-
+  add_custom_target(cppcheck
     # First cppcheck
     COMMAND ${CPPCHECK_PATH} ${CPPCHECK_BASE} ${CPPCHECK_EXTRA} -I ${CPPCHECK_INCLUDE_DIRS} ${CPPCHECK_RULES} `${CPPCHECK_FIND}`
 
     # Second cppcheck
     COMMAND ${CPPCHECK_PATH} ${CPPCHECK_BASE} --enable=missingInclude `${CPPCHECK_FIND}`
+  )
 
+  add_custom_target(cpplint
     # cpplint cppcheck
-    COMMAND python ${IGNITION_CMAKE_CODECHECK_DIR}/cpplint.py --extensions=cc,hh --quiet `${CPPCHECK_FIND}`
+    COMMAND ${PYTHON_EXECUTABLE} ${IGNITION_CMAKE_CODECHECK_DIR}/cpplint.py --extensions=cc,hh --quiet `${CPPCHECK_FIND}`
   )
 
+  add_custom_target(codecheck
+    DEPENDS cpplint cppcheck
+  )
 endfunction()

cmake/IgnPython.cmake

@@ -0,0 +1,25 @@
+# Copyright 2020 Open Source Robotics Foundation, Inc.
+#
+# 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.
+
+# Copied from ament/ament_cmake: ament_cmake/ament_cmake_core/cmake/core/python.cmake
+
+set(PYTHON_VERSION "" CACHE STRING
+  "Specify specific Python version to use ('major.minor' or 'major')")
+
+# if not specified otherwise use Python 3
+if(NOT PYTHON_VERSION)
+  set(PYTHON_VERSION "3")
+endif()
+
+find_package(PythonInterp ${PYTHON_VERSION} REQUIRED)

cmake/IgnUtils.cmake

@@ -1676,7 +1676,8 @@ macro(ign_build_tests)
 
     # Find the Python interpreter for running the
     # check_test_ran.py script
-    find_package(PythonInterp QUIET)
+
+    include(IgnPython)
 
     # Build all the tests
     foreach(target_name ${test_list})