python: enable freethreading in nanobind + cibuildwheel (experimental)

Author: pthom

imgui_bundle_cmake/internal/add_imgui_bundle_bindings.cmake

@@ -58,7 +58,7 @@ function(add_imgui_bundle_bindings)
         ${all_pybind_files}
         )
 
-    nanobind_add_module(${python_native_module_name} ${python_module_sources})
+    nanobind_add_module(${python_native_module_name} FREE_THREADED ${python_module_sources})
     target_compile_definitions(${python_native_module_name} PRIVATE VERSION_INFO=${PROJECT_VERSION})
 
     litgen_setup_module(${bound_library} ${python_native_module_name} ${python_wrapper_module_name} ${IMGUI_BUNDLE_PATH}/bindings)

pyproject.toml

@@ -103,6 +103,9 @@ build-verbosity = 1
 # Target python versions:
 build = ["cp312-*", "cp313-*", "cp314-*"]
 
+# Test freethreading support (no GIL)
+enable = ["cpython-freethreading"]
+
 # Tests
 test-requires = "pytest"
 test-command = "pytest {project}/tests"  # cibuildwheel doc says pytest {package}/tests !