TypeAliasType objects have no `__qualname__`

[AA-Turner]

Bug report

Bug description:

This means that introspection is worse for type statements declared e.g. within class bodies.

A

cc @JelleZijlstra

CPython versions tested on:

3.12, 3.13, 3.14, 3.15, CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-139817: Attribute __qualname__ is added to TypeAliasType #139919
• gh-139817: typing docs: Fix indentation of .. versionadded:: note for TypeAliasType.__qualname__ #140177
• gh-139817: Fix refleak in TypeAliasType(qualname=non_string) #140197

[efimov-mikhail]

I would like to make a PR for adding __qualname__, but maybe I'll be needed some guidance about it.

[JelleZijlstra]

There's two parts to this: adding a __qualname__ attribute to the TypeAliasType object (easy), and setting it correctly at runtime (hard). This will likely need changes to the bytecode, so that when we generate code for a type statement we pass the right qualname in. (Unless there's some clever way we can get it at runtime in the implementation of INTRINSIC_TYPEALIAS?) That probably means we can do it only in 3.15 at this point.

[xuantengh]

What the value of __qualname__ of TypeAliasType should be?

type Vec[T] = list[T]

print(Vec[int].__name__) # Vec
print(Vec[int].__qualname__) # Vec[int] ?

For example, when we have Vec[int], its __qualname__ should be Vec[int]?

[JelleZijlstra]

Vec[int] is an instance of types.GenericAlias, not TypeAliasType. It should not be part of this issue and should not have a __qualname__ attribute.

[efimov-mikhail]

Qualified names for TypeAliasType have been added on main branch. So, this issue may be closed? Do we want to add qualified names for other typing objects or port them onto previous versions?

[JelleZijlstra]

Thank you! We shouldn't backport this because it's a new feature, and if any other typing objects have similar issues, we should open a new issue. So that means we're done here.