fix: GetHashCode in generated string comparers hash the value instead of the comparer#946
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SteveDunn merged 4 commits intoJun 29, 2026
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…not the comparer __StringEqualityComparer.GetHashCode was calling _comparer.GetHashCode() with no argument, returning object.GetHashCode() on the comparer instance itself. Every value object therefore got the same hash code when using the generated Comparers, making hash-based collections degenerate to O(n). Fixed to pass obj._value to the comparer. Added regression tests to each StringComparisons test class asserting that two unequal values produce different hash codes.
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Hi @sirphilliptubell - many thanks for the PR, and good spot re. the bug! Would you mind running Thanks again! |
SteveDunn
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Jun 29, 2026
SteveDunn
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SteveDunn
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LGTM! Thanks for the contribution - much appreciated!
This was referenced Jul 10, 2026
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…not the comparer
__StringEqualityComparer.GetHashCode was calling _comparer.GetHashCode() with no argument, returning object.GetHashCode() on the comparer instance itself. Every value object therefore got the same hash code when using the generated Comparers, making hash-based collections degenerate to O(n).
Fixed to pass obj._value to the comparer. Added regression tests to each StringComparisons test class asserting that two unequal values produce different hash codes.