Improve error on starred assignment

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Bug Report

The syntax error message could perhaps be imporved when starred assignments are used incorrectly.

To Reproduce

# test.py
a = *b

Then run

python3 test.py
mypy test.py

Actual Behavior

I'm uncertain on what the expected behaviour should be so I'll just describe the actual behaviour, when running it under python3.11 python produces

File "/private/tmp/test.py", line 1
    a = *b
        ^^
SyntaxError: can't use starred expression here

Whereas mypy says

test.py:1: error: Can use starred expression only as assignment target
Found 1 error in 1 file (errors prevented further checking)

Now, at a glance I thought I can do what I'm doing but it still resulted in an error, also the error seems to indicate that *a = b is fine, but that is incorrect as well.

Your Environment

• Mypy version used: mypy 1.6.1 (compiled: yes)
• Mypy command-line flags: --new-type-inference
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.11.5

[JelleZijlstra]

Thanks for the report! I would suggest we simply copy CPython's error message "can't use starred expression here".

[parasiitism]

Could you please consider assigning this issue to me? I am enthusiastic about getting involved in the project and am eager to collaborate with your team to help address this matter.