Backport #1367 to Garden: Fix find Python3 logic (#1370)

* Find Python3 with find_package instead of GzPython,
  adapting the approach from gz-sim.

Signed-off-by: Steve Peters <[email protected]>

CMakeLists.txt

@@ -78,9 +78,30 @@ if (BUILD_SDF)
  # available during build time
  set(GZ_TOOLS_VER 2)
 
+ #################################################
+ # Find python
+ if (SKIP_PYBIND11)
+ message(STATUS "SKIP_PYBIND11 set - disabling python bindings")
+ find_package(Python3 COMPONENTS Interpreter)
+ else()
+ find_package(Python3 COMPONENTS Interpreter Development)
+ if (NOT Python3_Development_FOUND)
+ GZ_BUILD_WARNING("Python development libraries are missing: Python interfaces are disabled.")
+ else()
+ set(PYBIND11_PYTHON_VERSION 3)
+ find_package(pybind11 2.4 CONFIG QUIET)
+
+ if (pybind11_FOUND)
+ message (STATUS "Searching for pybind11 - found version ${pybind11_VERSION}.")
+ else()
+ GZ_BUILD_WARNING("pybind11 is missing: Python interfaces are disabled.")
+ message (STATUS "Searching for pybind11 - not found.")
+ endif()
+ endif()
+ endif()
+
  #################################################
  # Copied from catkin/cmake/empy.cmake
- include(GzPython)
  function(find_python_module module)
  # cribbed from http://www.cmake.org/pipermail/cmake/2011-January/041666.html
  string(TOUPPER ${module} module_upper)
@@ -130,30 +151,6 @@ if (BUILD_SDF)
  gz_find_package(gz-utils2 REQUIRED COMPONENTS cli)
  set(GZ_UTILS_VER ${gz-utils2_VERSION_MAJOR})
 
- ########################################
- # Python interfaces
- if (NOT PYTHON3_FOUND)
- GZ_BUILD_WARNING("Python is missing: Python interfaces are disabled.")
- message (STATUS "Searching for Python - not found.")
- else()
- message (STATUS "Searching for Python - found version ${Python3_VERSION}.")
-
- if (SKIP_PYBIND11)
- message(STATUS "SKIP_PYBIND11 set - disabling python bindings")
- else()
- set(PYBIND11_PYTHON_VERSION 3)
- find_package(pybind11 2.4 QUIET)
-
- if (${pybind11_FOUND})
- find_package(Python3 ${GZ_PYTHON_VERSION} REQUIRED COMPONENTS Development)
- message (STATUS "Searching for pybind11 - found version ${pybind11_VERSION}.")
- else()
- GZ_BUILD_WARNING("pybind11 is missing: Python interfaces are disabled.")
- message (STATUS "Searching for pybind11 - not found.")
- endif()
- endif()
- endif()
-
  gz_configure_build(HIDE_SYMBOLS_BY_DEFAULT QUIT_IF_BUILD_ERRORS)
 
  gz_create_packages()
@@ -162,7 +159,7 @@ if (BUILD_SDF)
  add_subdirectory(conf)
  add_subdirectory(doc)
  if (pybind11_FOUND AND NOT SKIP_PYBIND11)
-  add_subdirectory(python)
+  add_subdirectory(python)
  endif()
 endif(BUILD_SDF)