Bug report

Bug description:

Spotted by @wsfulton in GH-136258. I'm making an issue so I can attach it to his PR.

PyType_GetName is used incorrectly in two places:

There are two problems:

1. PyType_GetName returns a PyObject *, not a string (so the %s conversion is invalid).
2. It also returns a strong reference, which isn't consumed by PyErr_Format and thus is leaked.

Fixes to tests generally don't matter, but I think that this one is worth fixing. People look to the source for examples, and considering this is one of our only examples using it, I'd rather not leave people to think that PyType_GetName returns a string or borrowed reference.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• [3.14] gh-136288: Fix error message in _testcapi/vectorcall.c (GH-136258) #136294
• [3.13] gh-136288: Fix error message in _testcapi/vectorcall.c (GH-136258) #136295

• gh-136288: Correct error display in _testcapi/vectorcall.c #136258