DEPR: Remove SettingWithCopyWarning
🥳

We shouldn't merge before the actual release is out

**`_item_cache` removal**
closes #50547
closes #29411
closes #21391

**SettingWIthCopyWarning removal**
closes #18752
closes #9767
closes #14150
closes #16550
closes #17505
closes #38270
closes #39418
closes #39448
closes #41891
closes #45513
closes #50209
closes #55451

**Others Matt thinks**
closes #19102


wow this kills giant hacks that i wrote from a while back!

+1000000 This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Could you see if this works?

https://github.com/pandas-dev/pandas/issues/44866  > Could you see if this works?

https://github.com/pandas-dev/pandas/issues/44866

It works if you use it on a series but it will never work if you do

df["a"].foo = "something
df["a"].foo

because both df["a"] are different objects with CoW, so this can't work

We can close the issue though, the case doesn't make sense under CoW This PR closed an issue I subscribed to (#9767), and I had no idea why and how until I found https://pandas.pydata.org/pdeps/0007-copy-on-write.html. Leaving this here for others.