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Fix circular init in AOT equality comparer causing NRE on Mono #73

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Merged
bradwilson merged 1 commit into from
Mar 20, 2026
+9 −4
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Fix circular init in AOT equality comparer causing NRE on Mono #73

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13 changes: 9 additions & 4 deletions Sdk/AssertEqualityComparer_aot.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,13 +18,18 @@ namespace Xunit.Sdk
{
partial class AssertEqualityComparer
{
static readonly IEqualityComparer defaultComparer = new AssertEqualityComparerAdapter<object>(new AssertEqualityComparer<object>());

// Create a new instance each call (matching the non-AOT/reflection path behavior)
// rather than caching in a static field. A cached static field causes a circular
// static initialization dependency: the field initializer triggers
// AssertEqualityComparer<object>'s static initializer, which reads the field back
// via GetDefaultInnerComparer before it has been assigned. On Mono/WASM, this
// causes DefaultInnerComparer to be permanently null, leading to
// NullReferenceException when comparing value types via IStructuralEquatable.
internal static IEqualityComparer GetDefaultComparer(Type _) =>
defaultComparer;
new AssertEqualityComparerAdapter<object>(new AssertEqualityComparer<object>());

internal static IEqualityComparer GetDefaultInnerComparer(Type _) =>
defaultComparer;
new AssertEqualityComparerAdapter<object>(new AssertEqualityComparer<object>());
}

partial class AssertEqualityComparer<T>
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