`sqlite3.Row()` crashes when given a `Cursor` whose `__init__` was not called

Crash report

What happened?

sqlite3.Row() reads cursor->description without checking that the cursor was initialized, so a NULL slot segfaults the interpreter:

❯ python3
Python 3.14.6 (main, Jun 10 2026, 18:54:31) [GCC 15.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlite3
... sqlite3.Row(sqlite3.Cursor.__new__(sqlite3.Cursor), ())
...
Segmentation fault         (core dumped) python3

A PR is on the way.

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Linked PRs

• gh-156556

首先使用 sqlite3.Row(sqlite3.Cursor.new(sqlite3.Cursor), ()) 重現該命令，然後檢查 sqlite3.Row 對未初始化 Cursor 的處理。完成的標準是相同的輸入不再導致直譯器發生 segmentation fault，且回歸測試涵蓋率證明該行為是安全的。