gh-141805: avoid increase the set->used twice when the __eq__ trigger another add#142007
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kemingy wants to merge 6 commits intopython:mainfrom
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gh-141805: avoid increase the set->used twice when the __eq__ trigger another add#142007kemingy wants to merge 6 commits intopython:mainfrom
kemingy wants to merge 6 commits intopython:mainfrom
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…er add Signed-off-by: Keming <kemingy94@gmail.com>
Signed-off-by: Keming <kemingy94@gmail.com>
dr-carlos
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Nov 27, 2025
Misc/NEWS.d/next/Core_and_Builtins/2025-11-27-17-47-09.gh-issue-141805.TT0biF.rst
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Signed-off-by: Keming <kemingy94@gmail.com>
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efimov-mikhail
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This PR looks correct for me, just little nitpicks.
Misc/NEWS.d/next/Core_and_Builtins/2025-11-27-17-47-09.gh-issue-141805.TT0biF.rst
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Signed-off-by: Keming <kemingy94@gmail.com>
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Kindly ping @rhettinger, please take a look when you are free. Thanks! |
| else if (entry->hash == -1) { | ||
| assert (entry->key == dummy); | ||
| freeslot = entry; | ||
| goto found_unused_or_dummy; |
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No, this is incorrect.
Imagine you added two elements with the same hash, A and B. Then A hes been removed, and replaced with a dummy (this is why dummy is needed). Then we try to add B again. With your code, it will find a dummy in place of A, and replace it with B. Now you have two Bs in a set.
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gh-141805: goes directly to the
found_unused_or_dummywhen finding a dummy slot in set.addThis avoids triggering the
__eq__in the next iteration by thePyObject_RichCompareBool, which might introduce anotherset.addin the user code. Like:As described in #141805 (comment)