dotnet/roslyn

Nullable check ignores NotNullIfNotNullAttribute when the argument is method group

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#77,475 opened on 2025年3月9日

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Area-CompilersBugFeature - Nullable Reference Typeshelp wanted

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説明

.NET SDK 9.0.200:

Steps to Reproduce:

#nullable enable
using System.Linq; // Enumerable.Select

string[] a = ["1", "a"]; // element not null

_ = a.Select(Foo) // returns string?[]
    .First().ToString(); // CS8602, unexpected

_ = a.Select(t => Foo(t)) // returns string[]
    .First().ToString(); // correct, expected

[return: NotNullIfNotNull(nameof(x))]
string? Foo(string? x) => x;

Diagnostic Id:

CS8602

Expected Behavior:

Nullable check Does not ignore NotNullIfNotNullAttribute when the argument is method group

Actual Behavior:

Nullable check ignores NotNullIfNotNullAttribute when the argument is method group

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