Missing warnings on overriding a method with different nullability attributes #41368
Description
Relates to PR #41336
My attempts to fixing this resulted in a difficult cycle to fix, so the problem was separated into an issue.
Should take a look at this again after we investigate a solution for constraint binding cycles (#48154).
[Fact]
public void MaybeNullWhenTrue_OHI_Parameter_Generic_OnOverrides()
{
var source =
@"using System.Diagnostics.CodeAnalysis;
public class Base
{
public virtual bool F1<T>(T t1, out T t2, ref T t3, in T t4) => throw null!;
}
public class Derived : Base
{
public override bool F1<T>([MaybeNullWhen(true)]T t1, [MaybeNullWhen(true)] out T t2, [MaybeNullWhen(true)] ref T t3, [MaybeNullWhen(true)] in T t4) => throw null!; // t2, t3
}
";
var comp = CreateNullableCompilation(new[] { MaybeNullWhenAttributeDefinition, source });
// Note: we're missing warnings on F1 because the overridden method with substituted T from Derived has an oblivious T
comp.VerifyDiagnostics(
// TODO we should have warnings on t2 and t3
);
}The proposed fix was:
diff --git a/src/Compilers/CSharp/Portable/Symbols/TypeWithAnnotations.cs b/src/Compilers/CSharp/Portable/Symbols/TypeWithAnnotations.cs
index 76acfc3..d268af3 100644
--- a/src/Compilers/CSharp/Portable/Symbols/TypeWithAnnotations.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/TypeWithAnnotations.cs
@@ -486,7 +486,7 @@ internal TypeWithAnnotations SubstituteTypeCore(AbstractTypeMap typeMap)
}
else if (NullableAnnotation != NullableAnnotation.Oblivious)
{
- if (!typeSymbol.IsTypeParameterDisallowingAnnotation())
+ if (!typeSymbol.IsTypeParameterDisallowingAnnotation() || newTypeWithModifiers.Type.IsTypeParameterDisallowingAnnotation())
{
newAnnotation = NullableAnnotation;
}But that caused a cycle with
[Fact]
public void CircularConstraints()
{
var source =
@"class A<T> where T : B<T>.I
{
internal interface I { }
}
class B<T> : A<T> where T : A<T>.I
{
}";
var comp = CreateCompilation(new[] { source }, parseOptions: TestOptions.Regular7);
comp.VerifyDiagnostics();
comp = CreateCompilation(new[] { source }, options: WithNonNullTypesTrue(), parseOptions: TestOptions.Regular7, skipUsesIsNullable: true);
comp.VerifyDiagnostics(
// error CS8630: Invalid 'NullableContextOptions' value: 'Enable' for C# 7.0. Please use language version '8.0' or greater.
Diagnostic(ErrorCode.ERR_NullableOptionNotAvailable).WithArguments("NullableContextOptions", "Enable", "7.0", "8.0").WithLocation(1, 1)
);
comp = CreateCompilation(new[] { source }, options: WithNonNullTypesTrue());
comp.VerifyDiagnostics();
}with the following stack trace:
> Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol.IsValueType.get() Line 566 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbolExtensions.IsTypeParameterDisallowingAnnotation(Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol type) Line 63 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeWithAnnotations.SubstituteTypeCore(Microsoft.CodeAnalysis.CSharp.Symbols.AbstractTypeMap typeMap) Line 487 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeWithAnnotations.NonLazyType.SubstituteType(Microsoft.CodeAnalysis.CSharp.Symbols.TypeWithAnnotations type, Microsoft.CodeAnalysis.CSharp.Symbols.AbstractTypeMap typeMap) Line 888 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeWithAnnotations.SubstituteType(Microsoft.CodeAnalysis.CSharp.Symbols.AbstractTypeMap typeMap) Line 436 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.AbstractTypeMap.SubstituteNamedType(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol previous) Line 64 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SubstitutedNamedTypeSymbol.GetDeclaredBaseType(Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved) Line 142 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbolExtensions.GetNextDeclaredBase(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol type, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.CSharpCompilation compilation, ref Microsoft.CodeAnalysis.PooledObjects.PooledHashSet<Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol> visited) Line 191 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbolExtensions.GetNextBaseTypeNoUseSiteDiagnostics(Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol type, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.CSharpCompilation compilation, ref Microsoft.CodeAnalysis.PooledObjects.PooledHashSet<Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol> visited) Line 165 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupMembersInClass(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol type, string name, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, Microsoft.CodeAnalysis.CSharp.Binder originalBinder, Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol accessThroughType, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 750 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupMembersInClass(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol type, string name, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, Microsoft.CodeAnalysis.CSharp.Binder originalBinder, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 687 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupMembersInType(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol type, string name, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, Microsoft.CodeAnalysis.CSharp.Binder originalBinder, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 187 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupMembersInternal(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol nsOrType, string name, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, Microsoft.CodeAnalysis.CSharp.Binder originalBinder, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 164 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupSymbolsOrMembersInternal(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol qualifierOpt, string name, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 130 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.LookupSymbolsSimpleName(Microsoft.CodeAnalysis.CSharp.LookupResult result, Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol qualifierOpt, string plainName, int arity, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, Microsoft.CodeAnalysis.CSharp.LookupOptions options, bool diagnose, ref System.Collections.Generic.HashSet<Microsoft.CodeAnalysis.DiagnosticInfo> useSiteDiagnostics) Line 38 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindNonGenericSimpleNamespaceOrTypeOrAliasSymbol(Microsoft.CodeAnalysis.CSharp.Syntax.IdentifierNameSyntax node, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, bool suppressUseSiteDiagnostics, Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol qualifierOpt) Line 805 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindSimpleNamespaceOrTypeOrAliasSymbol(Microsoft.CodeAnalysis.CSharp.Syntax.SimpleNameSyntax syntax, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, bool suppressUseSiteDiagnostics, Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol qualifierOpt) Line 744 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindQualifiedName(Microsoft.CodeAnalysis.CSharp.Syntax.ExpressionSyntax leftName, Microsoft.CodeAnalysis.CSharp.Syntax.SimpleNameSyntax rightName, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, bool suppressUseSiteDiagnostics) Line 1306 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindNamespaceOrTypeOrAliasSymbol(Microsoft.CodeAnalysis.CSharp.Syntax.ExpressionSyntax syntax, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved, bool suppressUseSiteDiagnostics) Line 417 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindTypeOrAlias(Microsoft.CodeAnalysis.CSharp.Syntax.ExpressionSyntax syntax, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, Roslyn.Utilities.ConsList<Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol> basesBeingResolved) Line 312 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindTypeOrAliasOrConstraintKeyword(Microsoft.CodeAnalysis.CSharp.Syntax.TypeSyntax syntax, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, out Microsoft.CodeAnalysis.CSharp.Binder.ConstraintContextualKeyword keyword) Line 172 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindTypeOrConstraintKeyword(Microsoft.CodeAnalysis.CSharp.Syntax.TypeSyntax syntax, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, out Microsoft.CodeAnalysis.CSharp.Binder.ConstraintContextualKeyword keyword) Line 54 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindTypeParameterConstraints(Microsoft.CodeAnalysis.CSharp.Syntax.TypeParameterSyntax typeParameterSyntax, Microsoft.CodeAnalysis.CSharp.Syntax.TypeParameterConstraintClauseSyntax constraintClauseSyntax, bool isForOverride, Microsoft.CodeAnalysis.DiagnosticBag diagnostics) Line 225 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Binder.BindTypeParameterConstraintClauses(Microsoft.CodeAnalysis.CSharp.Symbol containingSymbol, System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol> typeParameters, Microsoft.CodeAnalysis.CSharp.Syntax.TypeParameterListSyntax typeParameterList, Microsoft.CodeAnalysis.SyntaxList<Microsoft.CodeAnalysis.CSharp.Syntax.TypeParameterConstraintClauseSyntax> clauses, ref System.Collections.Generic.IReadOnlyDictionary<Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol, bool> isValueTypeOverride, Microsoft.CodeAnalysis.DiagnosticBag diagnostics, bool isForOverride) Line 65 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol.MakeTypeParameterConstraints(Microsoft.CodeAnalysis.DiagnosticBag diagnostics) Line 308 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol.GetTypeParameterConstraintClause(int ordinal) Line 246 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SourceTypeParameterSymbol.GetTypeParameterConstraintClause() Line 554 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SourceTypeParameterSymbol.GetDeclaredConstraints() Line 571 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.SourceTypeParameterSymbol.HasValueTypeConstraint.get() Line 494 C#
Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol.IsValueType.get() Line 566 C#
I think a more common motivating scenario is:
[Fact]
public void Implement_GenericMethodWithNullabilityDifference()
{
var source =
@"#nullable enable
public interface I
{
T M<T>();
}
public class C : I
{
public T? M<T>() => default;
}";
var comp = CreateCompilation(source);
comp.VerifyEmitDiagnostics(
// We fail to warn
);
}