New version of NetAnalyzers throws CA1420 for delegates

[mattleibow]

Analyzer

Diagnostic ID: CA1420 Delegates with managed types as parameters or the return type require runtime marshalling to be enabled in the assembly where the delegate is defined

Analyzer source

NuGet Package: Microsoft.CodeAnalysis.NetAnalyzers

Version: 7.0.0-preview1.22302.1

Describe the bug

D:\a_work\1\s\src\Controls\src\Core\Platform\Tizen\Extensions\DragDropExtensions.cs(89,28): error CA1420: Delegates with managed types as parameters or the return type require runtime marshalling to be enabled in the assembly where the delegate is defined. [D:\a_work\1\s\src\Controls\src\Core\Controls.Core.csproj]

I started getting this issue after updating the package from:

• GOOD: 7.0.0-preview1.22274.2
• BAD: 7.0.0-preview1.22302.1
• BAD: 7.0.0-preview1.22379.1

Steps To Reproduce

1. Clone: https://github.com/dotnet/maui/tree/release/7.0.1xx-preview7
2. Update https://github.com/dotnet/maui/blob/release/7.0.1xx-preview7/eng/Versions.props#L39 to be the newer: 7.0.0-preview1.22302.1
3. dotnet build Microsoft.Maui.BuildTasks.slnf /p:configuration=Release

Expected behavior

Builds.

Actual behavior

Error.

Additional context

You may need to install the tizen workload, but I also saw this on other projects. I know this is a vague issue with a "download my code and build" but I am not sure what this error even means. Is it saying that delegates are not good?

I think it seems to be if some p/invoke has a delegate that uses a IntPtr

[Youssef1313]

dotnet/runtime#63714 has some info around the analyzer. To my understanding, the analyzer should fire only if you have System.Runtime.CompilerServices.DisableRuntimeMarshallingAttribute added to the assembly. Does dotnet/maui add this attribute somewhere?

[mattleibow]

I do not believe so. But all the parameters and things are just IntPtr, so that is really the most basic arg type...

[amin1best]

Hi,
Another reproduction:

dotnet new console

Replace the content of "Program.cs" with:

using System.Runtime.InteropServices;

class Program
{
    [StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Auto)]
    public struct testStruct
    {
        public CULong testPrp;
    }

    [UnmanagedFunctionPointerAttribute(CallingConvention.StdCall, CharSet = CharSet.Auto)]
    internal delegate CULong fncDlg(ref testStruct strcPrm);
    static void Main()
    {
        var lb = NativeLibrary.Load(@"test.dll");
        var fnc = NativeLibrary.GetExport(lb, "testFnc");

        testStruct strcObj = new testStruct();

        //#pragma warning disable CA1420
        var dlg = Marshal.GetDelegateForFunctionPointer<fncDlg>(fnc);
        //#pragma warning restore CA1420

        dlg(ref strcObj);

        NativeLibrary.Free(lb);
    }
}

and

dotnet build

show:

Program.cs(21,19): warning CA1420: Delegates with managed types as parameters or the return type require runtime marshalling to be enabled in the assembly where the delegat 
e is defined.

dotnet version: 7.0.100-preview.7.22377.5

[mattleibow]

Does it compile with the older nuger package?

[amin1best]

In 6.0.100-rc.2.21505.57, it works fine and doesn't warn.