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CSHARP-5793: Map MemoryExtensions Contains and SequenceEqual with null comparer to Enumerable methods with no comparer parameter #1828

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Merged
merged 11 commits into from
Nov 26, 2025
+50 −43
Merged

CSHARP-5793: Map MemoryExtensions Contains and SequenceEqual with null comparer to Enumerable methods with no comparer parameter #1828

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1e847fe
Handle 3-arg/null versions of MemoryExtensions Contains and SequenceE…
damieng Nov 24, 2025
95ce2a9
Alternative approach based on PR review.
damieng Nov 25, 2025
522d48e
Move IsOneOf args to a static readonly to avoid new array alloc per c…
damieng Nov 25, 2025
56dc0b5
Update src/MongoDB.Driver/Linq/Linq3Implementation/Translators/Expres…
damieng Nov 25, 2025
dac4bbd
Update src/MongoDB.Driver/Linq/Linq3Implementation/Translators/Expres…
damieng Nov 25, 2025
4dad79f
Update tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CShar…
damieng Nov 25, 2025
368eeae
Clarify private static field name.
damieng Nov 26, 2025
b380d62
Depluralize internal and test method names.
damieng Nov 26, 2025
a19fb9e
CSHARP-5793: Requested changes submitted as a commit to save you work
rstam Nov 26, 2025
5f4f07e
CSHARP-5793: Reject all suggested changes and revert to original commit
rstam Nov 26, 2025
73ebfbc
CSHARP-5793: Carry forward one minor change from rejected commits
rstam Nov 26, 2025
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46 changes: 10 additions & 36 deletions src/MongoDB.Driver/Linq/Linq3Implementation/Misc/ClrCompatExpressionRewriter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,11 @@ protected override Expression VisitMethodCall(MethodCallExpression node)

static Expression VisitContainsMethod(MethodCallExpression node, MethodInfo method, ReadOnlyCollection<Expression> arguments)
{
if (method.IsOneOf(MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValue, MemoryExtensionsMethod.ContainsWithSpanAndValue))
var hasNoComparer = method.IsOneOf(MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValue, MemoryExtensionsMethod.ContainsWithSpanAndValue);
var hasNullComparer = method.Is(MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValueAndComparer) && arguments[2] is ConstantExpression { Value: null };

// C# 14 targets MemoryExtensionsMethod.Contains, rewrite it back to Enumerable.Contains
if (hasNoComparer || hasNullComparer)
{
var itemType = method.GetGenericArguments().Single();
var span = arguments[0];
Expand All @@ -65,29 +69,17 @@ static Expression VisitContainsMethod(MethodCallExpression node, MethodInfo meth
[unwrappedSpan, value]);
}
}
else if (method.Is(MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValueAndComparer))
{
var itemType = method.GetGenericArguments().Single();
var span = arguments[0];
var value = arguments[1];
var comparer = arguments[2];

if (TryUnwrapSpanImplicitCast(span, out var unwrappedSpan) &&
unwrappedSpan.Type.ImplementsIEnumerableOf(itemType))
{
return
Expression.Call(
EnumerableMethod.ContainsWithComparer.MakeGenericMethod(itemType),
[unwrappedSpan, value, comparer]);
}
}

return node;
}

static Expression VisitSequenceEqualMethod(MethodCallExpression node, MethodInfo method, ReadOnlyCollection<Expression> arguments)
{
if (method.IsOneOf(MemoryExtensionsMethod.SequenceEqualWithReadOnlySpanAndReadOnlySpan, MemoryExtensionsMethod.SequenceEqualWithSpanAndReadOnlySpan))
var hasNoComparer = method.IsOneOf(MemoryExtensionsMethod.SequenceEqualWithReadOnlySpanAndReadOnlySpan, MemoryExtensionsMethod.SequenceEqualWithSpanAndReadOnlySpan);
var hasNullComparer = method.IsOneOf(MemoryExtensionsMethod.SequenceEqualWithReadOnlySpanAndReadOnlySpanAndComparer, MemoryExtensionsMethod.SequenceEqualWithSpanAndReadOnlySpanAndComparer) && arguments[2] is ConstantExpression { Value: null };

// C# 14 targets MemoryExtensionsMethod.SequenceEquals, rewrite it back to Enumerable.SequenceEquals
if (hasNoComparer || hasNullComparer)
{
var itemType = method.GetGenericArguments().Single();
var span = arguments[0];
Expand All @@ -104,24 +96,6 @@ static Expression VisitSequenceEqualMethod(MethodCallExpression node, MethodInfo
[unwrappedSpan, unwrappedOther]);
}
}
else if (method.IsOneOf(MemoryExtensionsMethod.SequenceEqualWithReadOnlySpanAndReadOnlySpanAndComparer, MemoryExtensionsMethod.SequenceEqualWithSpanAndReadOnlySpanAndComparer))
{
var itemType = method.GetGenericArguments().Single();
var span = arguments[0];
var other = arguments[1];
var comparer = arguments[2];

if (TryUnwrapSpanImplicitCast(span, out var unwrappedSpan) &&
TryUnwrapSpanImplicitCast(other, out var unwrappedOther) &&
unwrappedSpan.Type.ImplementsIEnumerableOf(itemType) &&
unwrappedOther.Type.ImplementsIEnumerableOf(itemType))
{
return
Expression.Call(
EnumerableMethod.SequenceEqualWithComparer.MakeGenericMethod(itemType),
[unwrappedSpan, unwrappedOther, comparer]);
}
}

return node;
}
Expand Down
47 changes: 40 additions & 7 deletions tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CSharp5749Tests.cs
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Expand Up @@ -48,6 +48,20 @@ public void MemoryExtensions_Contains_in_Where_should_work()
results.Select(x => x.Id).Should().Equal(2, 3);
}

[Fact]
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@rstam rstam Nov 25, 2025

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These new tests are fine.

I would also add these new tests:

    [Fact]
    public void Enumerable_Contains_with_null_comparer_should_work()
    {
        var collection = Fixture.Collection;
        var names = new[] { "Two", "Three" };

        var queryable = collection.AsQueryable().Where((C x) => names.Contains(x.Name, null));

        var results = queryable.ToArray();
        results.Select(x => x.Id).Should().Equal(2, 3);
    }

    [Fact]
    public void Enumerable_SequenceEqual_with_null_comparer_work()
    {
        var collection = Fixture.Collection;
        var ratings = new[] { 1, 9, 6 };

        var queryable = collection.AsQueryable().Where((C x) => ratings.SequenceEqual(x.Ratings, null));

        var results = queryable.ToArray();
        results.Select(x => x.Id).Should().Equal(3);
    }

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@damieng damieng Nov 25, 2025

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Done.

public void MemoryExtensions_Contains_in_Where_should_work_with_enum()
{
var collection = Fixture.Collection;
var daysOfWeek = new[] { DayOfWeek.Monday, DayOfWeek.Tuesday };

// Can't actually rewrite/fake these with MemoryExtensions.Contains overload with 3 args from .NET 10
// This test will activate correctly on .NET 10+
var queryable = collection.AsQueryable().Where(x => daysOfWeek.Contains(x.Day));

var results = queryable.ToArray();
results.Select(x => x.Id).Should().Equal(2, 3);
}

[Fact]
public void MemoryExtensions_Contains_in_Single_should_work()
{
Expand Down Expand Up @@ -93,6 +107,20 @@ public void MemoryExtensions_SequenceEqual_in_Where_should_work()
results.Select(x => x.Id).Should().Equal(3);
}

[Fact]
public void MemoryExtensions_SequenceEqual_in_Where_should_work_with_enum()
{
var collection = Fixture.Collection;
var daysOfWeek = new[] { DayOfWeek.Monday, DayOfWeek.Tuesday };

// Can't actually rewrite/fake these with MemoryExtensions.Contains overload with 3 args from .NET 10
// This test will activate correctly on .NET 10+
var queryable = collection.AsQueryable().Where(x => daysOfWeek.SequenceEqual(x.Days));

var results = queryable.ToArray();
results.Select(x => x.Id).Should().Equal(1);
}

[Fact]
public void MemoryExtensions_SequenceEqual_in_Single_should_work()
{
Expand Down Expand Up @@ -129,17 +157,19 @@ public void MemoryExtensions_SequenceEqual_in_Count_should_work()
public class C
{
public int Id { get; set; }
public DayOfWeek Day { get; set; }
public string Name { get; set; }
public int[] Ratings { get; set; }
public DayOfWeek[] Days { get; set; }
}

public sealed class ClassFixture : MongoCollectionFixture<C, BsonDocument>
{
protected override IEnumerable<BsonDocument> InitialData =>
[
BsonDocument.Parse("{ _id : 1, Name : \"One\", Ratings : [1, 2, 3, 4, 5] }"),
BsonDocument.Parse("{ _id : 2, Name : \"Two\", Ratings : [3, 4, 5, 6, 7] }"),
BsonDocument.Parse("{ _id : 3, Name : \"Three\", Ratings : [1, 9, 6] }")
BsonDocument.Parse("{ _id : 1, Name : \"One\", Day : 0, Ratings : [1, 2, 3, 4, 5], Days : [1, 2] }"),
BsonDocument.Parse("{ _id : 2, Name : \"Two\", Day : 1, Ratings : [3, 4, 5, 6, 7], Days: [1, 2, 3] }"),
BsonDocument.Parse("{ _id : 3, Name : \"Three\", Day : 2, Ratings : [1, 9, 6], Days: [2, 3, 4] }")
];
}

Expand Down Expand Up @@ -175,10 +205,13 @@ static Expression VisitContainsMethod(MethodCallExpression node, MethodInfo meth
if (source.Type.IsArray)
{
var readOnlySpan = ImplicitCastArrayToSpan(source, typeof(ReadOnlySpan<>), itemType);
return
Expression.Call(
MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValue.MakeGenericMethod(itemType),
[readOnlySpan, value]);

// Not worth checking for IEquatable<T> and generating 3 args overload as that requires .NET 10
// which if we had we could run the tests on natively without this visitor.

return Expression.Call(
MemoryExtensionsMethod.ContainsWithReadOnlySpanAndValue.MakeGenericMethod(itemType),
[readOnlySpan, value]);
}
}
else if (method.Is(EnumerableMethod.ContainsWithComparer))
Expand Down
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