cmake: add constraint_solver_pybind11 support

cmake/python.cmake

@@ -314,6 +314,7 @@ file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/algorithms/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/algorithms/python/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/bop/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/constraint_solver/__init__.py CONTENT "")
+file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/constraint_solver/python/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/glop/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/graph/__init__.py CONTENT "")
 file(GENERATE OUTPUT ${PYTHON_PROJECT_DIR}/graph/python/__init__.py CONTENT "")
@@ -461,6 +462,8 @@ add_custom_command(
    $<TARGET_FILE:min_cost_flow_pybind11> ${PYTHON_PROJECT}/graph/python
   COMMAND ${CMAKE_COMMAND} -E copy
    $<TARGET_FILE:pywrapcp> ${PYTHON_PROJECT}/constraint_solver
+  COMMAND ${CMAKE_COMMAND} -E copy
+   $<TARGET_FILE:constraint_solver_pybind11> ${PYTHON_PROJECT}/constraint_solver/python
   COMMAND ${CMAKE_COMMAND} -E copy
    $<TARGET_FILE:pywraplp> ${PYTHON_PROJECT}/linear_solver
   COMMAND ${CMAKE_COMMAND} -E copy
@@ -490,6 +493,7 @@ add_custom_command(
     max_flow_pybind11
     min_cost_flow_pybind11
     pywrapcp
+    constraint_solver_pybind11
     routing_pybind11
     pywraplp
     model_builder_helper_pybind11
@@ -526,6 +530,7 @@ add_custom_command(
   COMMAND ${stubgen_EXECUTABLE} -p ortools.graph.python.max_flow --output .
   COMMAND ${stubgen_EXECUTABLE} -p ortools.graph.python.min_cost_flow --output .
   COMMAND ${stubgen_EXECUTABLE} -p ortools.constraint_solver.pywrapcp --output .
+  COMMAND ${stubgen_EXECUTABLE} -p ortools.constraint_solver.python.constraint_solver --output .
   COMMAND ${stubgen_EXECUTABLE} -p ortools.linear_solver.pywraplp --output .
   COMMAND ${stubgen_EXECUTABLE} -p ortools.linear_solver.python.model_builder_helper --output .
   COMMAND ${stubgen_EXECUTABLE} -p pybind11_abseil.status --output .

ortools/constraint_solver/python/CMakeLists.txt

@@ -11,6 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# pywrapcp
 set_property(SOURCE routing.i PROPERTY CPLUSPLUS ON)
 set_property(SOURCE routing.i PROPERTY SWIG_MODULE_NAME pywrapcp)
 set_property(SOURCE routing.i PROPERTY COMPILE_DEFINITIONS
@@ -47,6 +48,33 @@ if(MSVC)
   target_link_libraries(pywrapcp PRIVATE ${Python3_LIBRARIES})
 endif()
 
+# constraint_solver
+pybind11_add_module(constraint_solver_pybind11 MODULE constraint_solver.cc)
+set_target_properties(constraint_solver_pybind11 PROPERTIES
+  LIBRARY_OUTPUT_NAME "constraint_solver")
+
+# note: macOS is APPLE and also UNIX !
+if(APPLE)
+  set_target_properties(constraint_solver_pybind11 PROPERTIES
+    SUFFIX ".so"
+    INSTALL_RPATH "@loader_path;@loader_path/../../../${PYTHON_PROJECT}/.libs"
+    )
+  set_property(TARGET constraint_solver_pybind11 APPEND PROPERTY
+    LINK_FLAGS "-flat_namespace -undefined suppress"
+    )
+elseif(UNIX)
+  set_target_properties(constraint_solver_pybind11 PROPERTIES
+    INSTALL_RPATH "$ORIGIN:$ORIGIN/../../../${PYTHON_PROJECT}/.libs"
+    )
+endif()
+
+target_link_libraries(constraint_solver_pybind11 PRIVATE
+  ${PROJECT_NAMESPACE}::ortools
+  pybind11_native_proto_caster
+)
+add_library(${PROJECT_NAMESPACE}::constraint_solver_pybind11 ALIAS constraint_solver_pybind11)
+
+# Test
 if(BUILD_TESTING)
   file(GLOB PYTHON_SRCS "*_test.py")
   foreach(FILE_NAME IN LISTS PYTHON_SRCS)

ortools/constraint_solver/python/constraint_solver_test.py

@@ -15,7 +15,7 @@
 """Test for constraint_solver pybind11 layer."""
 
 from absl.testing import absltest
-from ortools.constraint_solver import constraint_solver
+from ortools.constraint_solver.python import constraint_solver
 
 
 class ConstraintSolverTest(absltest.TestCase):

ortools/python/setup.py.in

@@ -71,6 +71,10 @@ setup(
             '$<TARGET_FILE_NAME:pywrapcp>',
             '*.pyi'
         ],
+        '@PYTHON_PROJECT@.constraint_solver.python':[
+            '$<TARGET_FILE_NAME:constraint_solver_pybind11>',
+            '*.pyi'
+        ],
         '@PYTHON_PROJECT@.linear_solver':[
             '$<TARGET_FILE_NAME:pywraplp>',
             '*.pyi'