SITL error with gazebo 9.6.0_2 on macOS Mojave: Eigen3 is found but >= 3.2.92

Using the latest master and gazebo I’m having the following build error:

➜  Firmware git:(master) make posix gazebo_solo
-- PX4 config file: /Users/dlw/Workspace/PX4/Firmware/boards/px4/sitl/default.cmake
-- PX4 config: px4_sitl_default
-- PX4 platform: posix
-- PX4 lockstep: enabled
-- PX4 version: v1.9.0-alpha-266-g939413fa06
-- cmake build type: RelWithDebInfo
-- The CXX compiler identification is AppleClang 10.0.0.10001044
-- The C compiler identification is AppleClang 10.0.0.10001044
-- The ASM compiler identification is AppleClang
-- Found assembler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Found PythonInterp: /usr/local/bin/python (found version "2.7.15")
-- Found PY_jinja2: /usr/local/lib/python2.7/site-packages/jinja2
-- PX4 ECL: Very lightweight Estimation & Control Library v0.9.0-608-gacde4eb
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default
ninja: Entering directory `/Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default'
[6/710] git submodule src/lib/ecl
[17/710] git submodule src/lib/DriverFramework
[22/710] git submodule src/drivers/gps/devices
[23/710] git submodule Tools/sitl_gazebo
[26/710] git submodule mavlink/include/mavlink/v2.0
[89/710] Performing configure step for 'sitl_gazebo'
FAILED: external/Stamp/sitl_gazebo/sitl_gazebo-configure
cd /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/build_gazebo && /usr/local/Cellar/cmake/3.13.3/bin/cmake -DCMAKE_INSTALL_PREFIX=/usr/local -DSEND_VISION_ESTIMATION_DATA=ON -GNinja /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo && /usr/local/Cellar/cmake/3.13.3/bin/cmake -E touch /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/external/Stamp/sitl_gazebo/sitl_gazebo-configure
-- install-prefix: /usr/local
-- The C compiler identification is AppleClang 10.0.0.10001044
-- The CXX compiler identification is AppleClang 10.0.0.10001044
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - found
-- Found Threads: TRUE
-- Boost version: 1.68.0
-- Found the following Boost libraries:
--   system
--   thread
--   timer
--   chrono
--   date_time
--   atomic
-- Found PkgConfig: /usr/local/bin/pkg-config (found version "0.29.2")
-- Checking for module 'bullet>=2.82'
--   Found bullet, version 2.88
-- Found Eigen3: /usr/local/include/eigen3 (Required is at least version "2.91.0")
CMake Error at /usr/local/share/dart/cmake/DARTFindEigen3.cmake:14 (message):
  Eigen3 is found but >= 3.2.92

      (3.3~beta1) is required
Call Stack (most recent call first):
  /usr/local/share/dart/cmake/dart_dartComponent.cmake:5 (include)
  /usr/local/share/dart/cmake/DARTConfig.cmake:63 (include)
  /usr/local/share/dart/cmake/DARTConfig.cmake:124 (dart_traverse_components)
  /usr/local/share/dart/cmake/DARTConfig.cmake:172 (dart_package_init)
  /usr/local/lib/cmake/gazebo/gazebo-config.cmake:124 (find_package)
  CMakeLists.txt:31 (find_package)


-- Configuring incomplete, errors occurred!
See also "/Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/build_gazebo/CMakeFiles/CMakeOutput.log".
[92/710] Building CXX object src/lib/parameters/CMakeFiles/parameters.dir/parameters.cpp.o
ninja: build stopped: subcommand failed.
make: *** [px4_sitl_default] Error 1

The current supported gazebo version is 8 - the version you have installed is not officially supported and still in alpha / beta state.

Thanks for the info. I’m happy for this to be noticed for anyone working on the alpha/beta support of gazebo9.

Unfortunately I’m also having issues with the PX4 stable branch with Gazebo 8.6 here.

master branch is also giving me build errors currently, but there’s a good chance I have a homebrew dependency messed up from bouncing between gazebo8 and 9.

➜  Firmware git:(master) make posix gazebo_solo
-- PX4 config file: /Users/dlw/Workspace/PX4/Firmware/boards/px4/sitl/default.cmake
-- PX4 config: px4_sitl_default
-- PX4 platform: posix
-- PX4 lockstep: enabled
-- PX4 version: v1.9.0-alpha-266-g939413fa06
-- cmake build type: RelWithDebInfo
-- The CXX compiler identification is AppleClang 10.0.0.10001044
-- The C compiler identification is AppleClang 10.0.0.10001044
-- The ASM compiler identification is AppleClang
-- Found assembler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Found PythonInterp: /usr/local/bin/python (found version "2.7.15")
-- Found PY_jinja2: /usr/local/lib/python2.7/site-packages/jinja2
-- PX4 ECL: Very lightweight Estimation & Control Library v0.9.0-608-gacde4eb
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default
ninja: Entering directory `/Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default'
[6/710] git submodule src/lib/ecl
[17/710] git submodule src/lib/DriverFramework
[22/710] git submodule src/drivers/gps/devices
[23/710] git submodule mavlink/include/mavlink/v2.0
[26/710] git submodule Tools/sitl_gazebo
[431/710] Performing configure step for 'sitl_gazebo'
-- install-prefix: /usr/local
-- The C compiler identification is AppleClang 10.0.0.10001044
-- The CXX compiler identification is AppleClang 10.0.0.10001044
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - found
-- Found Threads: TRUE
-- Boost version: 1.68.0
-- Found the following Boost libraries:
--   system
--   thread
--   timer
--   chrono
--   date_time
--   atomic
-- Found PkgConfig: /usr/local/bin/pkg-config (found version "0.29.2")
-- Checking for module 'bullet>=2.82'
--   Found bullet, version 2.88
-- Boost version: 1.68.0
-- Found the following Boost libraries:
--   thread
--   signals
--   system
--   filesystem
--   program_options
--   regex
--   iostreams
--   date_time
--   chrono
--   atomic
-- Found Protobuf: /usr/local/lib/libprotobuf.dylib (found version "3.6.1")
-- Boost version: 1.68.0
-- Looking for OGRE...
-- OGRE_PREFIX_WATCH changed.
-- Checking for module 'OGRE'
--   Found OGRE, version 1.9.0
-- Found Ogre Ghadamon (1.9.0)
-- Found OGRE: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreMain.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreMain.dylib
-- Looking for OGRE_Paging...
-- Found OGRE_Paging: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgrePaging.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgrePaging.dylib
-- Looking for OGRE_Terrain...
-- Found OGRE_Terrain: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreTerrain.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreTerrain.dylib
-- Looking for OGRE_Property...
-- Found OGRE_Property: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreProperty.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreProperty.dylib
-- Looking for OGRE_RTShaderSystem...
-- Found OGRE_RTShaderSystem: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreRTShaderSystem.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreRTShaderSystem.dylib
-- Looking for OGRE_Volume...
-- Found OGRE_Volume: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreVolume.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreVolume.dylib
-- Looking for OGRE_Overlay...
-- Found OGRE_Overlay: optimized;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreOverlay.dylib;debug;/usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/lib/libOgreOverlay.dylib
-- Checking for module 'libzmq>=3.2.0'
--   Found libzmq, version 4.3.1
-- Looking for zmq pkgconfig file - found
-- Checking for module 'uuid'
--   Found uuid, version 1.6.2
-- Looking for ignition-msgs - found
-- Found PythonInterp: /usr/local/bin/python (found version "2.7.15")
-- Found OpenCV: /usr/local (found version "4.0.1")
-- Found TinyXML: /usr/local/lib/libtinyxml.dylib
-- Checking for module 'OGRE'
--   Found OGRE, version 1.9.0
-- Building klt_feature_tracker without catkin
-- Building OpticalFlow with OpenCV
-- Found MAVLink: /Users/dlw/Workspace/PX4/Firmware/mavlink/include (found version "2.0")
-- catkin DISABLED
-- Checking for module 'protobuf'
--   Found protobuf, version 3.6.1
Gazebo version: 8.6
-- Performing Test COMPILER_SUPPORTS_CXX17
-- Performing Test COMPILER_SUPPORTS_CXX17 - Success
-- Performing Test COMPILER_SUPPORTS_CXX14
-- Performing Test COMPILER_SUPPORTS_CXX14 - Success
-- Performing Test COMPILER_SUPPORTS_CXX11
-- Performing Test COMPILER_SUPPORTS_CXX11 - Success
-- Performing Test COMPILER_SUPPORTS_CXX0X
-- Performing Test COMPILER_SUPPORTS_CXX0X - Success
-- Using C++17 compiler
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/build_gazebo
[617/710] Linking CXX static library src/drivers/camera_trigger/libdrivers__camera_trigger.a
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(pwm.cpp.o) has no symbols
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(seagull_map2.cpp.o) has no symbols
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(gpio.cpp.o) has no symbols
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(pwm.cpp.o) has no symbols
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(seagull_map2.cpp.o) has no symbols
/Library/Developer/CommandLineTools/usr/bin/ranlib: file: src/drivers/camera_trigger/libdrivers__camera_trigger.a(gpio.cpp.o) has no symbols
[707/710] Performing build step for 'sitl_gazebo'
FAILED: external/Stamp/sitl_gazebo/sitl_gazebo-build
cd /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/build_gazebo && /usr/local/Cellar/cmake/3.13.3/bin/cmake --build . && /usr/local/Cellar/cmake/3.13.3/bin/cmake -E touch /Users/dlw/Workspace/PX4/Firmware/build/px4_sitl_default/external/Stamp/sitl_gazebo/sitl_gazebo-build
[1/78] Running cpp protocol buffer compiler on msgs/Odometry.proto
[2/78] Running cpp protocol buffer compiler on msgs/CommandMotorSpeed.proto
[3/78] Running cpp protocol buffer compiler on msgs/Int32.proto
[4/78] Running cpp protocol buffer compiler on msgs/MotorSpeed.proto
[5/78] Running cpp protocol buffer compiler on msgs/Groundtruth.proto
[6/78] Running cpp protocol buffer compiler on msgs/Imu.proto
[7/78] Running cpp protocol buffer compiler on msgs/IRLock.proto
[8/78] Running cpp protocol buffer compiler on msgs/Float.proto
[9/78] Running cpp protocol buffer compiler on msgs/Range.proto
[10/78] Running cpp protocol buffer compiler on msgs/SITLGps.proto
[11/78] Running cpp protocol buffer compiler on msgs/OpticalFlow.proto
[12/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/3DR_gps_mag/3DR_gps_mag-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/3DR_gps_mag/3DR_gps_mag.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/3DR_gps_mag/3DR_gps_mag-gen.sdf
[13/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/pixhawk/pixhawk-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/pixhawk/pixhawk.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/pixhawk/pixhawk-gen.sdf
[14/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/c920/c920-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/c920/c920.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/c920/c920-gen.sdf
[15/78] Running cpp protocol buffer compiler on msgs/Wind.proto
[16/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/mb1240-xl-ez4/mb1240-xl-ez4-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/mb1240-xl-ez4/mb1240-xl-ez4.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/mb1240-xl-ez4/mb1240-xl-ez4-gen.sdf
[17/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/px4flow/px4flow-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/px4flow/px4flow.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/px4flow/px4flow-gen.sdf
[18/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/r200/r200-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/r200/r200.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/r200/r200-gen.sdf
[19/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/matrice_100/matrice_100-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/matrice_100/matrice_100.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/matrice_100/matrice_100-gen.sdf
[20/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/sf10a/sf10a-gen.sdf
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/sf10a/sf10a.sdf.jinja -> /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/sf10a/sf10a-gen.sdf
[21/78] Building CXX object OpticalFlow/CMakeFiles/OpticalFlow.dir/src/optical_flow.cpp.o
[22/78] Building CXX object CMakeFiles/gazebo_mavlink_interface.dir/src/geo_mag_declination.cpp.o
[23/78] Generating /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/models/iris/iris.sdf

[24/78] Building CXX object CMakeFiles/std_msgs.dir/Int32.pb.cc.o
[25/78] Building CXX object CMakeFiles/nav_msgs.dir/Odometry.pb.cc.o
[26/78] Linking CXX shared library libstd_msgs.dylib
[27/78] Linking CXX shared library libnav_msgs.dylib
[28/78] Building CXX object CMakeFiles/physics_msgs.dir/Wind.pb.cc.o
[29/78] Building CXX object CMakeFiles/gazebo_lidar_plugin.dir/src/gazebo_lidar_plugin.cpp.o
[30/78] Building CXX object CMakeFiles/gazebo_gimbal_controller_plugin.dir/src/gazebo_gimbal_controller_plugin.cpp.o
[31/78] Building CXX object CMakeFiles/gazebo_multirotor_base_plugin.dir/src/gazebo_multirotor_base_plugin.cpp.o
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/src/gazebo_multirotor_base_plugin.cpp:21:
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/gazebo_multirotor_base_plugin.h:29:
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/common.h:68:10: warning: expression result unused [-Wunused-value]
    for( e_model; e_model; e_model=e_model->NextSiblingElement("model") )
         ^~~~~~~
1 warning generated.
[32/78] Building CXX object CMakeFiles/LiftDragPlugin.dir/src/liftdrag_plugin/liftdrag_plugin.cpp.o
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/src/liftdrag_plugin/liftdrag_plugin.cpp:21:
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/common.h:68:10: warning: expression result unused [-Wunused-value]
    for( e_model; e_model; e_model=e_model->NextSiblingElement("model") )
         ^~~~~~~
1 warning generated.
[33/78] Linking CXX shared library libphysics_msgs.dylib
[34/78] Building CXX object CMakeFiles/gazebo_vision_plugin.dir/src/gazebo_vision_plugin.cpp.o
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/src/gazebo_vision_plugin.cpp:41:
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/gazebo_vision_plugin.h:46:
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/common.h:68:10: warning: expression result unused [-Wunused-value]
    for( e_model; e_model; e_model=e_model->NextSiblingElement("model") )
         ^~~~~~~
1 warning generated.
[35/78] Building CXX object OpticalFlow/CMakeFiles/OpticalFlow.dir/src/px4flow.cpp.o
[36/78] Building CXX object OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_px4.cpp.o
[37/78] Building CXX object CMakeFiles/gazebo_motor_model.dir/src/gazebo_motor_model.cpp.o
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/src/gazebo_motor_model.cpp:22:
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/gazebo_motor_model.h:38:
/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/include/common.h:68:10: warning: expression result unused [-Wunused-value]
    for( e_model; e_model; e_model=e_model->NextSiblingElement("model") )
         ^~~~~~~
1 warning generated.
[38/78] Building CXX object OpticalFlow/klt_feature_tracker/CMakeFiles/klt_feature_tracker.dir/src/trackFeatures.cpp.o
FAILED: OpticalFlow/klt_feature_tracker/CMakeFiles/klt_feature_tracker.dir/src/trackFeatures.cpp.o
/Library/Developer/CommandLineTools/usr/bin/c++  -DLIBBULLET_VERSION=2.88 -DLIBBULLET_VERSION_GT_282 -I/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/include -isystem /usr/local/Cellar/gazebo8/8.6.0_5/include -isystem /usr/local/Cellar/gazebo8/8.6.0_5/include/gazebo-8 -isystem /usr/local/Cellar/bullet/2.88/include/bullet -isystem /usr/local/Cellar/bullet/2.88/include -isystem /usr/local/include/simbody -isystem /usr/local/include -isystem /usr/local/Cellar/sdformat5/5.3.0_4/include/sdformat-5.3 -isystem /usr/local/include/ignition/math3 -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE/Terrain -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE/Paging -isystem /usr/local/Cellar/ignition-transport3/3.1.0_2/include/ignition/transport3 -isystem /usr/local/Cellar/zeromq/4.3.1_1/include -isystem /usr/local/Cellar/ossp-uuid/1.6.2_2/include/ossp -isystem /usr/local/include/ignition/msgs0 -isystem /usr/local/include/opencv4 -fpic -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk -MD -MT OpticalFlow/klt_feature_tracker/CMakeFiles/klt_feature_tracker.dir/src/trackFeatures.cpp.o -MF OpticalFlow/klt_feature_tracker/CMakeFiles/klt_feature_tracker.dir/src/trackFeatures.cpp.o.d -o OpticalFlow/klt_feature_tracker/CMakeFiles/klt_feature_tracker.dir/src/trackFeatures.cpp.o -c /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/src/trackFeatures.cpp
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/src/trackFeatures.cpp:40:
In file included from /usr/local/include/opencv4/opencv2/core/core.hpp:48:
In file included from /usr/local/include/opencv4/opencv2/core.hpp:52:
/usr/local/include/opencv4/opencv2/core/cvdef.h:656:4: error: "OpenCV 4.x+ requires enabled C++11 support"
#  error "OpenCV 4.x+ requires enabled C++11 support"
   ^
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/src/trackFeatures.cpp:40:
In file included from /usr/local/include/opencv4/opencv2/core/core.hpp:48:
In file included from /usr/local/include/opencv4/opencv2/core.hpp:57:
/usr/local/include/opencv4/opencv2/core/matx.hpp:143:15: error: no template named 'initializer_list' in namespace 'std'
    Matx(std::initializer_list<_Tp>); //!< initialize from an initializer list
         ~~~~~^
/usr/local/include/opencv4/opencv2/core/matx.hpp:361:14: error: no template named 'initializer_list' in namespace 'std'
    Vec(std::initializer_list<_Tp>);
        ~~~~~^
/usr/local/include/opencv4/opencv2/core/matx.hpp:664:28: error: no template named 'initializer_list' in namespace 'std'
Matx<_Tp, m, n>::Matx(std::initializer_list<_Tp> list)
                      ~~~~~^
/usr/local/include/opencv4/opencv2/core/matx.hpp:1016:24: error: no template named 'initializer_list' in namespace 'std'
Vec<_Tp, cn>::Vec(std::initializer_list<_Tp> list)
                  ~~~~~^
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/src/trackFeatures.cpp:40:
In file included from /usr/local/include/opencv4/opencv2/core/core.hpp:48:
In file included from /usr/local/include/opencv4/opencv2/core.hpp:58:
/usr/local/include/opencv4/opencv2/core/types.hpp:2371:29: error: no member named 'val' in 'cv::Scalar_<float>'
    return Scalar_<float>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                          ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2371:43: error: no member named 'val' in 'cv::Scalar_<float>'
    return Scalar_<float>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                        ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2371:57: error: no member named 'val' in 'cv::Scalar_<float>'
    return Scalar_<float>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                                      ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2371:71: error: no member named 'val' in 'cv::Scalar_<float>'
    return Scalar_<float>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                                                    ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2378:30: error: no member named 'val' in 'cv::Scalar_<double>'
    return Scalar_<double>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                           ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2378:44: error: no member named 'val' in 'cv::Scalar_<double>'
    return Scalar_<double>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                         ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2378:58: error: no member named 'val' in 'cv::Scalar_<double>'
    return Scalar_<double>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                                       ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2378:72: error: no member named 'val' in 'cv::Scalar_<double>'
    return Scalar_<double>(a.val[0] * s, a.val[1] * s, a.val[2] * s, a.val[3] * s);
                                                                     ~ ^
/usr/local/include/opencv4/opencv2/core/types.hpp:2411:24: error: no matching constructor for initialization of 'Matx<double, 4, 1>'
    Matx<double, 4, 1> c((Matx<double, 4, 4>)a, b, Matx_MatMulOp());
                       ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/opencv4/opencv2/core/matx.hpp:203:28: note: candidate constructor not viable: no known conversion from 'Matx<[2 * ...], 4>' to 'const Matx<[2 * ...], 1 aka 1>' for 1st argument
    template<typename _T2> Matx(const Matx<_Tp, m, n>& a, _T2 alpha, Matx_ScaleOp);
                           ^
/usr/local/include/opencv4/opencv2/core/matx.hpp:122:5: note: candidate constructor not viable: no known conversion from 'Matx<double, 4, 4>' to 'double' for 1st argument
    Matx(_Tp v0, _Tp v1, _Tp v2); //!< 1x3 or 3x1 matrix
    ^
/usr/local/include/opencv4/opencv2/core/matx.hpp:201:5: note: candidate constructor not viable: no known conversion from 'Matx<[2 * ...], 4>' to 'const Matx<[2 * ...], 1 aka 1>' for 1st argument
    Matx(const Matx<_Tp, m, n>& a, const Matx<_Tp, m, n>& b, Matx_AddOp);
    ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
[39/78] Building CXX object CMakeFiles/gazebo_irlock_plugin.dir/src/gazebo_irlock_plugin.cpp.o
[40/78] Building CXX object OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_opencv.cpp.o
FAILED: OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_opencv.cpp.o
/Library/Developer/CommandLineTools/usr/bin/c++  -DLIBBULLET_VERSION=2.88 -DLIBBULLET_VERSION_GT_282 -DOpticalFlow_EXPORTS -I/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/OpticalFlow_INCLUDE_DIRS -I/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/include -I/Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/external/klt_feature_tracker/include -isystem /usr/local/Cellar/gazebo8/8.6.0_5/include -isystem /usr/local/Cellar/gazebo8/8.6.0_5/include/gazebo-8 -isystem /usr/local/Cellar/bullet/2.88/include/bullet -isystem /usr/local/Cellar/bullet/2.88/include -isystem /usr/local/include/simbody -isystem /usr/local/include -isystem /usr/local/Cellar/sdformat5/5.3.0_4/include/sdformat-5.3 -isystem /usr/local/include/ignition/math3 -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE/Terrain -isystem /usr/local/Cellar/ogre1.9/1.9-20160714-108ab0bcc69603dba32c0ffd4bbbc39051f421c9_7/include/OGRE/Paging -isystem /usr/local/Cellar/ignition-transport3/3.1.0_2/include/ignition/transport3 -isystem /usr/local/Cellar/zeromq/4.3.1_1/include -isystem /usr/local/Cellar/ossp-uuid/1.6.2_2/include/ossp -isystem /usr/local/include/ignition/msgs0 -isystem /usr/local/include/opencv4 -fpic -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk -fPIC -MD -MT OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_opencv.cpp.o -MF OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_opencv.cpp.o.d -o OpticalFlow/CMakeFiles/OpticalFlow.dir/src/flow_opencv.cpp.o -c /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/src/flow_opencv.cpp
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/src/flow_opencv.cpp:41:
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/include/flow_opencv.hpp:44:
In file included from /usr/local/include/opencv4/opencv2/opencv.hpp:52:
In file included from /usr/local/include/opencv4/opencv2/core.hpp:52:
/usr/local/include/opencv4/opencv2/core/cvdef.h:656:4: error: "OpenCV 4.x+ requires enabled C++11 support"
#  error "OpenCV 4.x+ requires enabled C++11 support"
   ^
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/src/flow_opencv.cpp:41:
In file included from /Users/dlw/Workspace/PX4/Firmware/Tools/sitl_gazebo/external/OpticalFlow/include/flow_opencv.hpp:44:
In file included from /usr/local/include/opencv4/opencv2/opencv.hpp:52:
In file included from /usr/local/include/opencv4/opencv2/core.hpp:57:
/usr/local/include/opencv4/opencv2/core/matx.hpp:143:15: error: no template named 'initializer_list' in namespace 'std'
    Matx(std::initializer_list<_Tp>); //!< initialize from an initializer list
         ~~~~~^

Gazebo9 and current master are working great, now.