Wrong `TypeError` message

[Locked-chess-official]

Bug report

Bug description:

>>> type(print).__new__(type(print))
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    type(print).__new__(type(print))
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
TypeError: object.__new__(builtin_function_or_method) is not safe, use builtin_function_or_method.__new__()

The type(print).__new__ is not object.__new__, so the message is wrong. The correct message is "cannot create 'builtin_function_or_method' instances"

CPython versions tested on:

3.13

Operating systems tested on:

Windows

[terryjreedy]

The premise "type(print).new is not object.new" is wrong.

>>> tp = type(print)
>>> tp
<class 'builtin_function_or_method'>
>>> tpn = tp.__new__
>>> tpn
<built-in method __new__ of type object at 0x00007FF89566EBF0>
>>> tpn is object.__new__
True

The error message you see seems to be generic when the class passed to object.new is not object. So the first part of the error message is correct. For instance:

>>> object.__new__(object)
<object object at 0x0000022B62D41870>
>>> object.__new__(int)
Traceback (most recent call last):
  File "<pyshell#25>", line 1, in <module>
    object.__new__(int)
TypeError: object.__new__(int) is not safe, use int.__new__()
>>> int.__new__(int)
0
int.__new__(float)
Traceback (most recent call last):
  File "<pyshell#39>", line 1, in <module>
    int.__new__(float)
TypeError: int.__new__(float): float is not a subtype of int

I don't really understand this since the doc for __new__ says that int.__new__(int) should call object.__new__(int) to get a bare object with __class__ set to int. Maybe the internal implementation has changed.

What is different about int is that it is a class with its own __new__ method whereas class 'builtin_function_or_method', having a fixed set of pre-built instances, does not. It therefore inherits object.new. In this case, the second part of the message is nonsense.

A solution would be to give class 'builtin_function_or_method' a __new__ method that raise a message like the one suggested.

[serhiy-storchaka]

I don't really understand this since the doc for __new__ says that int.__new__(int) should call object.__new__(int) to get a bare object with __class__ set to int.

No, it doesn't. It says

Typical implementations create a new instance of the class by invoking the superclass’s __new__() method using super().__new__(cls[, ...]) with appropriate arguments and then modifying the newly created instance as necessary before returning it.

But this is only relevant for Python classes. Extension classes are implemented differently, using the C API.

This issue is a duplicate of #78465.