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Merged
jjonescz merged 2 commits into from
Jul 2, 2026
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Unsafe evolution: avoid errors inside nameof #84325

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Unsafe evolution: avoid errors inside nameof
jjonescz Jun 29, 2026
c0a758b
Extend tests
jjonescz Jul 1, 2026
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5 changes: 5 additions & 0 deletions src/Compilers/CSharp/Portable/Binder/Binder_Unsafe.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,11 @@ internal void ReportDiagnosticsIfUnsafeMemberAccess(DiagnosticBag diagnostics, S

private void ReportDiagnosticsIfUnsafeMemberAccess<T>(DiagnosticBag diagnostics, Symbol symbol, T arg, Func<T, Location?> location)
{
if (IsInsideNameof)

@AlekseyTs AlekseyTs Jun 30, 2026 •
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IsInsideNameof

It looks like we have BinderFlags.SuppressUnsafeDiagnostics. Also, it looks like in one of the recent changes we set BinderFlags.UnsafeRegion flag on a binder to achieve the same goal for params collections declarations. I think we should simply stick to setting proper BinderFlags for NameOfBinder. Also, we probably should standardize on BinderFlags.SuppressUnsafeDiagnostics for the purpose of suppressing diagnostics. #Closed

@jjonescz jjonescz Jul 1, 2026

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That's what I looked at first, but it doesn't seem to be as simple in NameofBinder. It computes the fact whether we are in nameof operator lazily, via some non-trivial logic, hence I don't think we can just statically set a flag when creating the binder.

{
return;
}

var useUpdatedMemorySafetyRules = this.Compilation.SourceModule.UseUpdatedMemorySafetyRules;
var callerUnsafeMode = symbol.GetCallerUnsafeMode(this.FieldsBeingBound);
if (!useUpdatedMemorySafetyRules && callerUnsafeMode != CallerUnsafeMode.Implicit)
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99 changes: 99 additions & 0 deletions src/Compilers/CSharp/Test/CSharp15/UnsafeEvolutionTests.cs
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Expand Up @@ -4717,6 +4717,105 @@ unsafe event System.Action E { add { } remove { } }
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "D").WithLocation(12, 22));
}

[Fact]
public void UnsafeDeclarations_NameOf()
{
var source = """
#pragma warning disable CS0649, CS8019, CS8321 // unused field, using, local function
using unsafe U = int*;

_ = nameof(U);
_ = nameof(F);
_ = nameof(C);
_ = nameof(S);
_ = nameof(I);
_ = nameof(R);
_ = nameof(D);
_ = nameof(X.F);
_ = nameof(X.M);
_ = nameof(X.P);
_ = nameof(X.Pg);
_ = nameof(X.Ps);
_ = nameof(X.E);

unsafe void F() { }
unsafe class C;
unsafe struct S;
unsafe interface I;
unsafe record R;
unsafe delegate void D();
class X
{
public unsafe int F;
public unsafe void M() { }
public unsafe int P { get; set; }
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public int Pg { unsafe get; set; }
public int Ps { get; unsafe set; }
public unsafe event System.Action E { add { } remove { } }
}
""";

CreateCompilation(source, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics(
// (29,21): error CS8652: The feature 'updated memory safety rules' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.
// public int Pg { unsafe get; set; }
Diagnostic(ErrorCode.ERR_FeatureInPreview, "unsafe").WithArguments("updated memory safety rules").WithLocation(29, 21),
// (30,26): error CS8652: The feature 'updated memory safety rules' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.
// public int Ps { get; unsafe set; }
Diagnostic(ErrorCode.ERR_FeatureInPreview, "unsafe").WithArguments("updated memory safety rules").WithLocation(30, 26));

CreateCompilation(source, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics();
CreateCompilation(source, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics();
CreateCompilation(source, options: TestOptions.UnsafeReleaseExe.WithUpdatedMemorySafetyRules()).VerifyEmitDiagnostics(
// (19,14): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe class C;
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "C").WithLocation(19, 14),
// (20,15): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe struct S;
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "S").WithLocation(20, 15),
// (21,18): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe interface I;
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "I").WithLocation(21, 18),
// (22,15): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe record R;
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "R").WithLocation(22, 15),
// (23,22): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe delegate void D();
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "D").WithLocation(23, 22));
}

[Fact]
public void UnsafeDeclarations_NameOf_CompatMode()
{
var source = """
#pragma warning disable CS0649, CS8321 // unused field, local function

_ = nameof(F);
_ = nameof(D);
_ = nameof(X.F);
_ = nameof(X.M);
_ = nameof(X.P);
_ = nameof(X.E);

unsafe void F(int* p) { }
unsafe delegate int* D();
class X
{
public unsafe int* F;
public unsafe void M(int* p) { }
public unsafe int* P { get; set; }
public unsafe event System.Action<int*[]> E { add { } remove { } }
}
""";

CreateCompilation(source, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics();
CreateCompilation(source, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics();
CreateCompilation(source, options: TestOptions.UnsafeReleaseExe).VerifyEmitDiagnostics();
CreateCompilation(source, options: TestOptions.UnsafeReleaseExe.WithUpdatedMemorySafetyRules()).VerifyEmitDiagnostics(
// (11,22): warning CS9377: The 'unsafe' modifier does not have any effect here under the current memory safety rules.
// unsafe delegate int* D();
Diagnostic(ErrorCode.WRN_UnsafeMeaningless, "D").WithLocation(11, 22));
}

[Fact]
public void UnsafeDeclarations_PointerToManagedType()
{
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