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Reusing variable previously defined with walrus operator triggers used-before-def error #14626

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goldenfire6 opened this issue Feb 6, 2023 · 1 comment · Fixed by #14646
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Reusing variable previously defined with walrus operator triggers used-before-def error #14626

goldenfire6 opened this issue Feb 6, 2023 · 1 comment · Fixed by #14646
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bug mypy got something wrong topic-pep-572 PEP 572 (walrus operator) topic-possibly-undefined possibly-undefined error code

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@goldenfire6
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To Reproduce

x = 3
z = (y := str(x)).index(y.lower())

Expected Behavior

Should be no errors -- this code does not error using mypy v0.991 or prior, so this seems to be a new issue with v1.0.0.

Actual Behavior

error: Name "y" is used before definition [used-before-def]

Your Environment

  • Mypy version used: 1.0.0
  • Mypy command-line flags: none
  • Python version used: 3.9
@goldenfire6 goldenfire6 added the bug mypy got something wrong label Feb 6, 2023
@hauntsaninja hauntsaninja added the topic-possibly-undefined possibly-undefined error code label Feb 6, 2023
@AlexWaygood AlexWaygood added the topic-pep-572 PEP 572 (walrus operator) label Feb 7, 2023
@hauntsaninja hauntsaninja mentioned this issue Feb 7, 2023
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@ilinum ilinum mentioned this issue Feb 8, 2023
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@ilinum
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ilinum commented Feb 8, 2023

Thanks for reporting! We will include the fix in the 1.0.1 release.

JukkaL pushed a commit that referenced this issue Feb 8, 2023
@ilinum
[used before def] correctly handle walrus operator (#14646)
6b56dc0 
Fixes #14626.

I believe changing the way that we analyze call expression makes sense
(first, we analyze the callee, then we analyze the arguments).
ilinum added a commit to ilinum/mypy that referenced this issue Feb 8, 2023
@ilinum
[used before def] correctly handle walrus operator (python#14646)
e683aa4 
Fixes python#14626.

I believe changing the way that we analyze call expression makes sense
(first, we analyze the callee, then we analyze the arguments).
ilinum added a commit to ilinum/mypy that referenced this issue Feb 8, 2023
@ilinum
[used before def] correctly handle walrus operator (python#14646)
4e2a113 
Fixes python#14626.

I believe changing the way that we analyze call expression makes sense
(first, we analyze the callee, then we analyze the arguments).
@ilinum ilinum mentioned this issue Feb 8, 2023
Merged
ilinum added a commit that referenced this issue Feb 9, 2023
@ilinum
[backport] [used before def] correctly handle walrus operator (#14646) (
c090ca2 
#14654)

Fixes #14626.

I believe changing the way that we analyze call expression makes sense
(first, we analyze the callee, then we analyze the arguments).
@AlexWaygood AlexWaygood mentioned this issue Feb 12, 2023
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[used before def] correctly handle walrus operator ilinum/mypy
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@goldenfire6 @ilinum @hauntsaninja @AlexWaygood