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Improve a check for inheritance relationship between types during binary operator re-inference in nullable walker #80272

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Merged
merged 1 commit into from
Sep 17, 2025
Merged

Improve a check for inheritance relationship between types during binary operator re-inference in nullable walker #80272

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2 changes: 1 addition & 1 deletion src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5493,7 +5493,7 @@ [new BoundExpressionWithNullability(leftOperand.Syntax, leftOperand, leftUnderly
derivedType = derivedType.StrippedType();
var discardedUseSiteInfo = CompoundUseSiteInfo<AssemblySymbol>.Discarded;
var conversion = _conversions.ClassifyBuiltInConversion(derivedType, baseType, isChecked: false, ref discardedUseSiteInfo);
if (conversion.Exists && !conversion.IsExplicit)
if (conversion.Kind is ConversionKind.Identity or ConversionKind.ImplicitReference)
{
return derivedType;
}
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34 changes: 34 additions & 0 deletions src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs
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Expand Up @@ -147317,6 +147317,40 @@ class Program
);
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80255")]
public void ReinferMethod_Span_01()
{
var source = """
#nullable enable
using System;
class C
{
bool M(ReadOnlySpan<int> a, Span<int> b)
{
return b == a;
}
}
""";
CreateCompilation(source, targetFramework: TargetFramework.Net90).VerifyDiagnostics();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80255")]
public void ReinferMethod_Span_02()
{
var source = """
#nullable enable
using System;
class C
{
bool M(ReadOnlySpan<int> a, Span<int> b)
{
return a == b;
}
}
""";
CreateCompilation(source, targetFramework: TargetFramework.Net90).VerifyDiagnostics();
}

[Fact]
[WorkItem(38726, "https://github.com/dotnet/roslyn/issues/38726")]
public void CollectionInitializerBoxingConversion()
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