On 2018-05-03 11:30, Victor Stinner wrote:
Please don't queue backward incompatible changes for Python 4.0. You should use the regular deprecation process.
I don't really see how that can be done here. As Stefan said
The problem is that this change does not really fit into the deprecation cycle since there is no specific use case to warn about.
The PEP proposes to change an implementation detail. It's really hard to determine at runtime whether code is relying on that implementation detail. We could insert a DeprecationWarning in some places, but those would mostly be false positives (a DeprecationWarning is shown but the code won't break).
On top of that, there is no way to show a DeprecationWarning for code like "type(x) is foo".