Enable capability to build with -Wpedantic.

Author: leander-dsouza

rosidl_generator_py/resource/_idl_pkg_typesupport_entry_point.c.em

@@ -21,6 +21,19 @@ include_directives = set()
 register_functions = []
 }@
 #include <Python.h>
+#include <string.h>
+
+// Convert a function pointer to void * via memcpy for use with PyCapsule_New().
+static inline void *
+_funcptr_to_capsule_ptr(void (* fn)(void))
+{
+  _Static_assert(
+    sizeof(void *) == sizeof(fn),
+    "void * and function pointer must have the same size");
+  void * ptr;
+  memcpy(&ptr, &fn, sizeof(ptr));
+  return ptr;
+}
 
 static PyMethodDef @(package_name)__methods[] = {
   {NULL, NULL, 0, NULL}  /* sentinel */

rosidl_generator_py/resource/_msg_pkg_typesupport_entry_point.c.em

@@ -74,7 +74,7 @@ function_names = ['create_ros_message', 'destroy_ros_message', 'convert_from_py'
   PyObject * pyobject_@(function_name) = NULL;
   pyobject_@(function_name) = PyCapsule_New(
 @[    if function_name != 'type_support']@
-    (void *)&@('__'.join(message.structure.namespaced_type.namespaces + [module_name]))__@(function_name),
+    _funcptr_to_capsule_ptr((void (*)(void)) & @('__'.join(message.structure.namespaced_type.namespaces + [module_name]))__@(function_name)),
 @[    else]@
     (void *)ROSIDL_GET_MSG_TYPE_SUPPORT(@(', '.join(message.structure.namespaced_type.namespaced_name()))),
 @[    end if]@