bpo-44698: Restore complex pow behaviour for small integral exponents #27772
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mdickinson
commented
Aug 15, 2021
| @@ -174,12 +174,7 @@ c_powi(Py_complex x, long n) | |||
| { | |||
| Py_complex cn; | |||
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| if (n > 100 || n < -100) { | |||
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This branch is now redundant: the bounds check is performed in the code that calls c_powi.
mdickinson
commented
Aug 15, 2021
mdickinson
added
needs backport to 3.9
gpshead
reviewed
Aug 15, 2021
mdickinson
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Aug 16, 2021
gpshead
approved these changes
Aug 16, 2021
|
Thanks @mdickinson for the PR 🌮🎉.. I'm working now to backport this PR to: 3.9, 3.10. |
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GH-27796 is a backport of this pull request to the 3.10 branch. |
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GH-27797 is a backport of this pull request to the 3.9 branch. |
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@gpshead Thank you for the review! |
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Aug 17, 2021
…pythonGH-27772) (cherry picked from commit 4b9a2dc) Co-authored-by: Mark Dickinson <mdickinson@enthought.com>
miss-islington
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…pythonGH-27772) (cherry picked from commit 4b9a2dc) Co-authored-by: Mark Dickinson <mdickinson@enthought.com>
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PR #27278 fixed undefined behaviour in complex exponentiation, but also changed the behaviour for exponentiations whose exponent was a small integer but not actually an
int, for example as in(3+4j)**2.0. In particular, the overflow behaviour for these expressions changed:Prior to #27278:
After #27278 :
This PR restores the old behaviour, but does not re-introduce the undefined behaviour fixed by the original PR.
https://bugs.python.org/issue44698