C# 12 compiler bug? (.NET 8.0.1)

[ruxo]

Hello everyone,

Sorry if this channel is not appropriate for reporting C# compiler issue but I've no idea where to report it. I just found out an issue with C# when declaring an explicit event block and using the primary constructor in a class, as in the following example:

Console.WriteLine("Hello, World!");

interface ITest
{
    event Action SomeAction;
}

sealed class Test(ITest otherTest) : ITest
{
    public event Action SomeAction {
        add => otherTest.SomeAction += value;
        remove => otherTest.SomeAction -= value;
    }
}

When building it with .NET 8.0.1, the build will fail with a NullReferenceException error messages. Here's a sample:

PS C:\temp\Test> dotnet build
MSBuild version 17.8.3+195e7f5a3 for .NET
  Determining projects to restore...
  All projects are up-to-date for restore.
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error : Process terminated. System.NullReferenceException: Object reference not set to an instance of an object. [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol.get_ParameterCount() [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.InMethodBinder.LookupSymbolsInSingleBinder(LookupResult result, String name, Int32 arity, ConsList`1 basesBeing Resolved, LookupOptions options, Binder originalBinder, Boolean diagnose, CompoundUseSiteInfo`1& useSiteInfo) [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.LookupSymbolsInternal(LookupResult result, String name, Int32 arity, ConsList`1 basesBeingResolved, Look upOptions options, Boolean diagnose, CompoundUseSiteInfo`1& useSiteInfo) [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.LookupSymbolsWithFallback(LookupResult result, String name, Int32 arity, CompoundUseSiteInfo`1& useSiteI nfo, ConsList`1 basesBeingResolved, LookupOptions options) [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.LookupIdentifier(LookupResult lookupResult, SimpleNameSyntax node, Boolean invoked, CompoundUseSiteInfo` 1& useSiteInfo) [C:\temp\Test\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.IdentifierUsedAsValueFinder.CheckIdentifier(Binder enclosingBinder, IdentifierNameSyntax id) [C:\temp\Te st\Test.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.IdentifierUsedAsValueFinder.CheckIdentifiersInNode(CSharpSyntaxNode node, Binder binder) [C:\temp\Test\T est.csproj]
C:\Program Files\dotnet\sdk\8.0.101\Roslyn\Microsoft.CSharp.Core.targets(84,5): error :    at Microsoft.CodeAnalysis.CSharp.Binder.CapturedParametersFinder.GetCapturedParameters(SynthesizedPrimaryConstructor primaryConstructor) [C:\tem p\Test\Test.csproj]

I hope this'd somehow reach the development team.

Best,
Rux

Update:

This issue is reported to Roslyn repo at dotnet/roslyn#71669

[HaloFour]

Can you report to the Roslyn repo? They deal with the implementation of the compiler.

[ruxo]

Thank you :)