Migrating Flax from returning FrozenDicts to returning regular dicts. More details can be found in this [announcement](https://github.com/google/flax/discussions/3191)

flax/configurations.py

@@ -109,11 +109,12 @@ def temp_flip_flag(var_name: str, var_value: bool):
     default=False,
     help=("When adopting outside modules, don't clobber existing names."))
 
-#TODO(marcuschiam): remove this feature flag once regular dict migration is complete
+# TODO(marcuschiam): remove this feature flag once regular dict migration is complete
 flax_return_frozendict = define_bool_state(
     name='return_frozendict',
-    default=True,
-    help=('Whether to return FrozenDicts when calling init or apply.'))
+    default=False,
+    help='Whether to return FrozenDicts when calling init or apply.',
+)
 
 flax_fix_rng = define_bool_state(
     name ='fix_rng_separator',

tests/core/core_lift_test.py

@@ -164,7 +164,6 @@ def false_fn(scope, x):
     self.assertEqual(vars['state'], {'true_count': 1, 'false_count': 1})
     np.testing.assert_allclose(y1, -y2)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_switch(self):
     def f(scope, x, index):
       scope.variable('state', 'a_count', lambda: 0)

tests/linen/linen_attention_test.py

@@ -144,7 +144,6 @@ def test_causal_mask_1d(self):
     np.testing.assert_allclose(mask_1d, mask_1d_simple,)
 
   @parameterized.parameters([((5,), (1,)), ((6, 5), (2,))])
-  @temp_flip_flag('return_frozendict', False)
   def test_decoding(self, spatial_shape, attn_dims):
     bs = 2
     num_heads = 3

tests/linen/linen_module_test.py

@@ -1098,7 +1098,6 @@ def test(self):
     A().test()
     self.assertFalse(setup_called)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_module_pass_as_attr(self):
 
     class A(nn.Module):
@@ -1129,7 +1128,6 @@ def __call__(self, x):
     }
     self.assertTrue(tree_equals(var_shapes, ref_var_shapes))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_module_pass_in_closure(self):
     a = nn.Dense(2)
 
@@ -1154,7 +1152,6 @@ def __call__(self, x):
     self.assertTrue(tree_equals(var_shapes, ref_var_shapes))
     self.assertIsNone(a.name)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_submodule_adoption(self):
 
     class Encoder(nn.Module):
@@ -1210,7 +1207,6 @@ def __call__(self, x):
     }
     self.assertTrue(tree_equals(var_shapes, ref_var_shapes))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_submodule_adoption_pytree(self):
 
     class A(nn.Module):
@@ -1254,7 +1250,6 @@ def __call__(self, c, x):
                 lambda x, y: np.testing.assert_allclose(x, y, atol=1e-7),
                 counters, ref_counters)))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_submodule_adoption_sharing(self):
     dense = functools.partial(nn.Dense, use_bias=False)
 
@@ -1305,7 +1300,6 @@ def __call__(self, x):
     }
     self.assertTrue(tree_equals(var_shapes, ref_var_shapes))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_named_submodule_adoption(self):
     dense = functools.partial(nn.Dense, use_bias=False)
 
@@ -1360,7 +1354,6 @@ def __call__(self, x):
       }
     self.assertTrue(tree_equals(var_shapes, ref_var_shapes))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_submodule_pytree_adoption_sharing(self):
 
     class A(nn.Module):

tests/linen/linen_transforms_test.py

@@ -807,7 +807,6 @@ def __call__(self, x):
     y3 = Ctrafo(a2, b).apply(p2, x)
     np.testing.assert_allclose(y1, y3, atol=1e-7)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_toplevel_submodule_adoption_pytree_transform(self):
     class A(nn.Module):
       @nn.compact
@@ -852,7 +851,6 @@ def __call__(self, c, x):
             cntrs, ref_cntrs)
         ))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_partially_applied_module_constructor_transform(self):
     k = random.PRNGKey(0)
     x = jnp.ones((3,4,4))
@@ -870,7 +868,6 @@ def test_partially_applied_module_constructor_transform(self):
     }
     self.assertTrue(tree_equals(init_vars_shapes, ref_var_shapes))
 
-  @temp_flip_flag('return_frozendict', False)
   def test_partial_module_method(self):
     k = random.PRNGKey(0)
     x = jnp.ones((3,4,4))
@@ -1505,7 +1502,6 @@ def false_fn(mdl, x):
 
         return nn.cond(pred, true_fn, false_fn, self, x)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_switch(self):
     class Foo(nn.Module):
       @nn.compact
@@ -1540,7 +1536,6 @@ def c_fn(mdl, x):
     self.assertEqual(vars['state'], {'a_count': 1, 'b_count': 1, 'c_count': 1})
     np.testing.assert_allclose(y1, y3)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_switch_multihead(self):
     class Foo(nn.Module):
       def setup(self) -> None:

tests/linen/summary_test.py

@@ -181,7 +181,6 @@ def test_module_summary(self):
         row.counted_variables,
       )
 
-  @temp_flip_flag('return_frozendict', False)
   def test_module_summary_with_depth(self):
     """
     This test creates a Table using `module_summary` set the `depth` argument to `1`,
@@ -240,7 +239,6 @@ def test_module_summary_with_depth(self):
     self.assertEqual(table[3].module_variables, table[3].counted_variables)
 
 
-  @temp_flip_flag('return_frozendict', False)
   def test_tabulate(self):
     """
     This test creates a string representation of a Module using `Module.tabulate`
@@ -323,7 +321,6 @@ def test_tabulate_with_method(self):
     self.assertIn("(block_method)", module_repr)
     self.assertIn("(cnn_method)", module_repr)
 
-  @temp_flip_flag('return_frozendict', False)
   def test_tabulate_function(self):
     """
     This test creates a string representation of a Module using `Module.tabulate`
@@ -370,7 +367,6 @@ def test_tabulate_function(self):
     self.assertIn("79.4 KB", lines[-3])
 
 
-  @temp_flip_flag('return_frozendict', False)
   def test_lifted_transform(self):
     class LSTM(nn.Module):
       features: int
@@ -406,7 +402,6 @@ def __call__(self, x):
     self.assertIn("ScanLSTM/ii", lines[13])
     self.assertIn("Dense", lines[13])
 
-  @temp_flip_flag('return_frozendict', False)
   def test_lifted_transform_no_rename(self):
     class LSTM(nn.Module):
       features: int
@@ -442,7 +437,6 @@ def __call__(self, x):
     self.assertIn("ScanLSTMCell_0/ii", lines[13])
     self.assertIn("Dense", lines[13])
 
-  @temp_flip_flag('return_frozendict', False)
   def test_module_reuse(self):
     class ConvBlock(nn.Module):
       @nn.compact
@@ -524,7 +518,6 @@ def __call__(self):
     self.assertIn('x: 3.141592', lines[7])
     self.assertIn('4.141592', lines[7])
 
-  @temp_flip_flag('return_frozendict', False)
   def test_partitioned_params(self):
 
     class Classifier(nn.Module):