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Boolean expression performs redundant bool check #3567

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#7176
Closed
Boolean expression performs redundant bool check#3567
#7176

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@dimpolo
dimpolo
opened on Mar 11, 2022
n = 0

class Test:
    def __bool__(self):
        global n
        n += 1
        return False

Test() and False or False
assert n == 1

CPython optimizes this check in:
https://github.com/python/cpython/blob/54ab9ad312ea53db40e31712454272e1d4c0315f/Python/compile.c#L8708-L8721

Activity

  1. crazymerlyn commented on Sep 7, 2024

    @crazymerlyn
    crazymerlyn
    on Sep 7, 2024
    Contributor

    Looks like the assertion fails again since python 3.12: https://godbolt.org/z/qoKcdvz4T

  2. moreal commented on Feb 14, 2026

    @moreal
    moreal
    on Feb 14, 2026
    Contributor

    In CPython 3.14, the assertion has started to pass again.

    https://godbolt.org/z/1Genzf9sE

    Image
  3. moreal
    added 2 commits that reference this issue on Feb 15, 2026

    Add runtime test for redundant __bool__ check (issue RustPython#3567)

    42e08bd

    Add runtime test for redundant __bool__ check (issue RustPython#3567)

    d8ccc98
  4. youknowone
    closed this as completedin #7176on Feb 17, 2026
  5. youknowone
    added a commit that references this issue on Feb 17, 2026

    Optimize redundant bool check (#7176)

    d07d522
  6. youknowone
    added a commit that references this issue on Mar 22, 2026

    Optimize redundant bool check (RustPython#7176)

    18f5812
  7. youknowone
    added a commit that references this issue on Sep 16, 2026

    Optimize redundant bool check (#7176)

    4b292f4
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