#nullable enable
using System.Diagnostics.CodeAnalysis;

public class C
{
    public void M0(string? x)
    {
        local(ref x);
        
        void local([NotNull] ref string? x)
        {
            x = null;
        } // no warning, but one was expected
    }
    
    void M1([NotNull] ref string? x)
    {
        x = null;
    } // warning CS8777: Parameter 'x' must have a non-null value when exiting.
}