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Unexpected "incompatible type" error when chaining bytes(filter()) #12247

@ion201

Description

@ion201

Bug Report

Mypy reports a strange type error when calling bytes(filter(...)) like below.

Write the following contents to a file and run mypy:

f = filter(lambda ch: chr(ch), b"hello")
bytes(f)

bytes(filter(lambda ch: chr(ch), b"hello"))

Mypy reports an error on line 4 but not on lines 1/2, despite the two sections being functionally identical. The expected result is that there should be no errors in this code example.

> mypy /tmp/test.py
/tmp/test.py:4: error: Argument 1 to "chr" has incompatible type "SupportsIndex"; expected "int"
Found 1 error in 1 file (checked 1 source file)

Your Environment

  • Mypy version used: mypy 0.931
  • Mypy command-line flags: none
  • Mypy configuration options from mypy.ini (and other config files): none
  • Python version used: python 3.10.2
  • Operating system and version: Arch linux and windows 10

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    bugmypy got something wrongtopic-type-contextType context / bidirectional inference

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