For a frozenset, `frozenset.copy()`, `copy.copy()` and `frozenset()` don't do a copy while `copy.deepcopy()` does

[hyperkai]

Bug report

Bug description:

For a frozenset, frozenset.copy(), copy.copy() and frozenset() don't do a copy which is a bug as shown below:

import copy

A = frozenset([0, 1, 2])

B = A.copy()
B = copy.copy(A)
B = frozenset(A)

print(A is B)
# True

While copy.deepcopy() does a copy properly as shown below:

import copy

A = frozenset([0, 1, 2])

B = copy.deepcopy(A)

print(A is B)
# False

In addition, for a set, set.copy(), copy.copy(), set() and copy.deepcopy() do a copy properly as shown below:

import copy

A = {0, 1, 2}

B = A.copy()
B = copy.copy(A)
B = frozenset(A)
B = copy.deepcopy(A)

print(A is B)
# False

CPython versions tested on:

3.12

Operating systems tested on:

Windows

[StanFromIreland]

This is not a bug, frozensets are immutable and copies are shallow. Please check the docs or even just google before opening an issue, one of the first results I get: https://stackoverflow.com/questions/37100944/i-think-immutable-types-like-frozenset-and-tuple-not-actually-copied-what-is-th

[hyperkai]

For a tuple, string and bytes, even copy.deepcopy() doesn't do a copy as shown below:

import copy

A = (0, 1, 2)
B = copy.deepcopy(A)

print(A is B)
# True

import copy

A = 'Hello'
B = copy.deepcopy(A)

print(A is B)
# True

import copy

A = b'Hello'
B = copy.deepcopy(A)

print(A is B)
# True

[hyperkai]

This is not a bug, frozensets are immutable and copies are shallow. Please check the docs or even just google before opening an issue, one of the first results I get: https://stackoverflow.com/questions/37100944/i-think-immutable-types-like-frozenset-and-tuple-not-actually-copied-what-is-th

Hey, frozenset.copy() doesn't do a copy so it should be deprecated and removed in the future.

[skirpichev]

Could you, please, first demonstrate issue?

Python 3.14.0rc3 (tags/v3.14.0rc3:1c5b28405a, Sep 22 2025, 14:58:42) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import copy
>>> f = frozenset({1, 2, 3})
>>> abc = f.copy()
>>> f is copy.copy(f)
True
>>> f is copy.deepcopy(f)
False
>>> f is f.copy()
True
>>> f is abc
True

Please note, that immutable compound objects expects hashable elements.