False positive? Syntax Error for a valid Python expression

[qexat]

Hi. First of all, thank you for building ptpython, it is amazing. It has been my go-to Python REPL coupled with my custom .pythonrc for a while now.

Now to the report:

>>> from __future__ import annotations
>>> x: (y := 5) = 3
[Syntax Error: named expression cannot be used within an annotation (<input>, line 1)]

The error does not show when the annotations feature is not present.

In my opinion, either the syntax error should not happen, or it should always occur, even when __future__.annotations is not enabled.

I searched the issue tracker with "named expression", "within an annotation" which did not yield any results.

Python: 3.12.7
ptpython: 3.0.29

[jonathanslenders]

Hi @qexat,

This has little to do with ptpython, but more with how Python works and evaluates annotations. The native Python shell does the same:

 $ python3
Python 3.12.3 (main, Nov  6 2024, 18:32:19) [GCC 13.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from __future__ import annotations
>>> x: (y := 5) = 3
  File "<stdin>", line 1
SyntaxError: named expression cannot be used within an annotation
>>>

[qexat]

I can reproduce now - I originally opened the issue specifically because it somehow didn't happen with the default Python REPL at the time, not sure what was going on