ENH: Use lazy copy in infer objects

pandas/core/generic.py

@@ -6313,7 +6313,7 @@ def __deepcopy__(self: NDFrameT, memo=None) -> NDFrameT:
         return self.copy(deep=True)
 
     @final
-    def infer_objects(self: NDFrameT, copy: bool_t = True) -> NDFrameT:
+    def infer_objects(self: NDFrameT, copy: bool_t | None = None) -> NDFrameT:
         """
         Attempt to infer better dtypes for object columns.
 

pandas/tests/copy_view/test_methods.py

@@ -322,6 +322,27 @@ def test_head_tail(method, using_copy_on_write):
     tm.assert_frame_equal(df, df_orig)
 
 
+def test_infer_objects(using_copy_on_write):
+    df = DataFrame({"a": [1, 2], "b": "c"})
+    df_orig = df.copy()
+    df2 = df.infer_objects()
+
+    if using_copy_on_write:
+        assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
+        assert np.shares_memory(get_array(df2, "b"), get_array(df, "b"))
+
+    else:
+        assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
+        assert not np.shares_memory(get_array(df2, "b"), get_array(df, "b"))
+
+    df2.iloc[0, 0] = 0
+    df2.iloc[0, 1] = "d"
+    if using_copy_on_write:
+        assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
+        assert not np.shares_memory(get_array(df2, "b"), get_array(df, "b"))
+    tm.assert_frame_equal(df, df_orig)
+
+
 def test_assign(using_copy_on_write):
     df = DataFrame({"a": [1, 2, 3]})
     df_orig = df.copy()