Здравствуйте, Passerby, Вы писали:

P>Могут ли локальные функции делать замыкание? И если могут, то как?

Также как и лямбды.

https://sharplab.io/#v2:D4AQTAjAsAUCDMACciDCiDetE+UglgHYAuiAsgBRGkCGAlJtrs9YgGYUMbIDsiNiANSIIAbkQBfJsxmJpMkHw51R8qTAlA==

using System;
public class C {
    public int M(int a) {
        int f() { return a + 1; }
            
        return f();
    }
}

using System.Diagnostics;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;

[assembly: CompilationRelaxations(8)]
[assembly: RuntimeCompatibility(WrapNonExceptionThrows = true)]
[assembly: Debuggable(DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints)]
[assembly: SecurityPermission(SecurityAction.RequestMinimum, SkipVerification = true)]
[assembly: AssemblyVersion("0.0.0.0")]
[module: UnverifiableCode]
public class C
{
    [StructLayout(LayoutKind.Auto)]
    [CompilerGenerated]
    private struct <>c__DisplayClass0_0
    {
        public int a;
    }

    public int M(int a)
    {
        <>c__DisplayClass0_0 <>c__DisplayClass0_ = default(<>c__DisplayClass0_0);
        <>c__DisplayClass0_.a = a;
        return <M>g__f|0_0(ref <>c__DisplayClass0_);
    }

    [CompilerGenerated]
    private static int <M>g__f|0_0(ref <>c__DisplayClass0_0 P_0)
    {
        return P_0.a + 1;
    }
}