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Fix O(n²) hash collisions in DuplicateDataRowAnalyzer #7803

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Fix O(n²) hash collisions in DuplicateDataRowAnalyzer #7803

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8cc9cb9
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Copilot Apr 24, 2026
8b1295a
Fix O(n²) hash collisions in DuplicateDataRowAnalyzer by including Va…
Copilot Apr 24, 2026
e74c7ff
Mirror float/double bit-pattern hashing from Equals into GetHashCode
Copilot Apr 24, 2026
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32 changes: 32 additions & 0 deletions src/Analyzers/MSTest.Analyzers/DuplicateDataRowAnalyzer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -153,9 +153,41 @@ public int GetHashCode(ImmutableArray<TypedConstant> obj)
{
hashCode.Add(typedConstant.Kind);
hashCode.Add(SymbolEqualityComparer.Default.GetHashCode(typedConstant.Type));

if (!typedConstant.IsNull)
{
if (typedConstant.Kind == TypedConstantKind.Array)
{
hashCode.Add(GetHashCode(typedConstant.Values));
}
else
{
AddTypedConstantValueHash(ref hashCode, typedConstant);
}
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}
}

return hashCode.ToHashCode();
}

private static void AddTypedConstantValueHash(ref RoslynHashCode hashCode, TypedConstant typedConstant)
{
if (typedConstant.Kind == TypedConstantKind.Primitive)
{
switch (typedConstant.Type?.SpecialType)
{
case SpecialType.System_Single:
// BitConverter.SingleToInt32Bits isn't available on netstandard2.0, so we use BitConverter.GetBytes instead.
hashCode.Add(BitConverter.ToInt32(BitConverter.GetBytes((float)typedConstant.Value!), 0));
return;

case SpecialType.System_Double:
hashCode.Add(BitConverter.DoubleToInt64Bits((double)typedConstant.Value!));
return;
}
}

hashCode.Add(typedConstant.Value);
}
}
}