[bug] Fix name collision in ti.dataclass (#6737)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

python/taichi/lang/struct.py

@@ -42,6 +42,7 @@ class Struct(TaichiOperations):
         dict_items([('v', [0. 0. 0.]), ('t', 1.0), ('A', {'v': [[0.], [0.], [0.]], 't': 1.0})])
     """
     _is_taichi_class = True
+    _instance_count = 0
 
     def __init__(self, *args, **kwargs):
         # converts lists to matrices and dicts to structs
@@ -96,12 +97,15 @@ def items(self):
         return self.entries.items()
 
     def _register_members(self):
-        for k in self.keys:
-            setattr(Struct, k,
-                    property(
-                        Struct._make_getter(k),
-                        Struct._make_setter(k),
-                    ))
+        # https://stackoverflow.com/questions/48448074/adding-a-property-to-an-existing-object-instance
+        cls = self.__class__
+        new_cls_name = cls.__name__ + str(cls._instance_count)
+        cls._instance_count += 1
+        properties = {
+            k: property(cls._make_getter(k), cls._make_setter(k))
+            for k in self.keys
+        }
+        self.__class__ = type(new_cls_name, (cls, ), properties)
 
     def _register_methods(self):
         for name, method in self.methods.items():
@@ -769,7 +773,7 @@ def dataclass(cls):
             and methods from the class attached.
     """
     # save the annotation fields for the struct
-    fields = cls.__annotations__
+    fields = getattr(cls, '__annotations__', {})
     # get the class methods to be attached to the struct types
     fields['__struct_methods'] = {
         attribute: getattr(cls, attribute)

tests/python/test_custom_struct.py

@@ -1,5 +1,6 @@
 import numpy as np
 from pytest import approx
+from taichi.lang.misc import get_host_arch_list
 
 import taichi as ti
 from tests import test_utils
@@ -443,3 +444,20 @@ def test():
         assert A.mass == 2.0
 
     test()
+
+
+@test_utils.test(arch=get_host_arch_list())
+def test_name_collision():
+    # https://github.com/taichi-dev/taichi/issues/6652
+    @ti.dataclass
+    class Foo:
+        zoo: ti.f32
+
+    @ti.dataclass
+    class Bar:
+        @ti.func
+        def zoo(self):
+            return 0
+
+    Foo()  # instantiate struct with zoo as member first
+    Bar()  # then instantiate struct with zoo as method