C#の匿名型やプロパティ、イテレーターなんかの言語機能は、コンパイラが内部的にフィールド、プロパティ、メソッド、クラスもろもろを生成します。
そのコンパイラが生成したフィールド、プロパティ、メソッド、クラスには、CompilerGeneratedという属性が付与されます。
SharpLabで、どういう風に付与されるか見てみましょう。
こんなC#のコードがあったら、
using System.Collections.Generic;
using System.Linq;
public class Person {
public string FirstName { get; }
public string LastName { get; }
public Person(string firstName, string lastName)
=> (FirstName, LastName) = (firstName, lastName);
}
public class Program {
public static void Main() {
var array = new int[] {3, 1, 4, 1, 5, 9, 2};
var result = array.Select(it => new { squared = it * it, cubed = it * it * it});
}
public static IEnumerable<int> Yield() {
yield return 0;
yield return 1;
yield return 2;
}
}
実際は、CompilerGeneratedが付与されたこんな感じになります。
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
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.Default | DebuggableAttribute.DebuggingModes.DisableOptimizations | DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints | DebuggableAttribute.DebuggingModes.EnableEditAndContinue)]
[assembly: SecurityPermission(SecurityAction.RequestMinimum, SkipVerification = true)]
[assembly: AssemblyVersion("0.0.0.0")]
[module: UnverifiableCode]
[CompilerGenerated]
[DebuggerDisplay("\\{ squared = {squared}, cubed = {cubed} }", Type = "<Anonymous Type>")]
internal sealed class <>f__AnonymousType0<<squared>j__TPar, <cubed>j__TPar>
{
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private readonly <squared>j__TPar <squared>i__Field;
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private readonly <cubed>j__TPar <cubed>i__Field;
public <squared>j__TPar squared => <squared>i__Field;
public <cubed>j__TPar cubed => <cubed>i__Field;
[DebuggerHidden]
public <>f__AnonymousType0(<squared>j__TPar squared, <cubed>j__TPar cubed)
{
<squared>i__Field = squared;
<cubed>i__Field = cubed;
}
[DebuggerHidden]
public override bool Equals(object value)
{
<>f__AnonymousType0<<squared>j__TPar, <cubed>j__TPar> anon = value as <>f__AnonymousType0<<squared>j__TPar, <cubed>j__TPar>;
return anon != null && EqualityComparer<<squared>j__TPar>.Default.Equals(<squared>i__Field, anon.<squared>i__Field) && EqualityComparer<<cubed>j__TPar>.Default.Equals(<cubed>i__Field, anon.<cubed>i__Field);
}
[DebuggerHidden]
public override int GetHashCode()
{
return (405075540 * -1521134295 + EqualityComparer<<squared>j__TPar>.Default.GetHashCode(<squared>i__Field)) * -1521134295 + EqualityComparer<<cubed>j__TPar>.Default.GetHashCode(<cubed>i__Field);
}
[DebuggerHidden]
public override string ToString()
{
object[] obj = new object[2];
<squared>j__TPar val = <squared>i__Field;
ref <squared>j__TPar reference = ref val;
<squared>j__TPar val2 = default(<squared>j__TPar);
object obj2;
if (val2 == null)
{
val2 = reference;
reference = ref val2;
if (val2 == null)
{
obj2 = null;
goto IL_0046;
}
}
obj2 = reference.ToString();
goto IL_0046;
IL_0046:
obj[0] = obj2;
<cubed>j__TPar val3 = <cubed>i__Field;
ref <cubed>j__TPar reference2 = ref val3;
<cubed>j__TPar val4 = default(<cubed>j__TPar);
object obj3;
if (val4 == null)
{
val4 = reference2;
reference2 = ref val4;
if (val4 == null)
{
obj3 = null;
goto IL_0081;
}
}
obj3 = reference2.ToString();
goto IL_0081;
IL_0081:
obj[1] = obj3;
return string.Format(null, "{{ squared = {0}, cubed = {1} }}", obj);
}
}
public class Person
{
[CompilerGenerated]
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private readonly string <FirstName>k__BackingField;
[CompilerGenerated]
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
private readonly string <LastName>k__BackingField;
public string FirstName
{
[CompilerGenerated]
get
{
return <FirstName>k__BackingField;
}
}
public string LastName
{
[CompilerGenerated]
get
{
return <LastName>k__BackingField;
}
}
public Person(string firstName, string lastName)
{
<FirstName>k__BackingField = firstName;
<LastName>k__BackingField = lastName;
}
}
public class Program
{
[Serializable]
[CompilerGenerated]
private sealed class <>c
{
public static readonly <>c <>9 = new <>c();
public static Func<int, <>f__AnonymousType0<int, int>> <>9__0_0;
internal <>f__AnonymousType0<int, int> <Main>b__0_0(int it)
{
return new <>f__AnonymousType0<int, int>(it * it, it * it * it);
}
}
[CompilerGenerated]
private sealed class <Yield>d__1 : IEnumerable<int>, IEnumerable, IEnumerator<int>, IDisposable, IEnumerator
{
private int <>1__state;
private int <>2__current;
private int <>l__initialThreadId;
int IEnumerator<int>.Current
{
[DebuggerHidden]
get
{
return <>2__current;
}
}
object IEnumerator.Current
{
[DebuggerHidden]
get
{
return <>2__current;
}
}
[DebuggerHidden]
public <Yield>d__1(int <>1__state)
{
this.<>1__state = <>1__state;
<>l__initialThreadId = Environment.CurrentManagedThreadId;
}
[DebuggerHidden]
void IDisposable.Dispose()
{
}
private bool MoveNext()
{
switch (<>1__state)
{
default:
return false;
case 0:
<>1__state = -1;
<>2__current = 0;
<>1__state = 1;
return true;
case 1:
<>1__state = -1;
<>2__current = 1;
<>1__state = 2;
return true;
case 2:
<>1__state = -1;
<>2__current = 2;
<>1__state = 3;
return true;
case 3:
<>1__state = -1;
return false;
}
}
bool IEnumerator.MoveNext()
{
//ILSpy generated this explicit interface implementation from .override directive in MoveNext
return this.MoveNext();
}
[DebuggerHidden]
void IEnumerator.Reset()
{
throw new NotSupportedException();
}
[DebuggerHidden]
IEnumerator<int> IEnumerable<int>.GetEnumerator()
{
if (<>1__state == -2 && <>l__initialThreadId == Environment.CurrentManagedThreadId)
{
<>1__state = 0;
return this;
}
return new <Yield>d__1(0);
}
[DebuggerHidden]
IEnumerator IEnumerable.GetEnumerator()
{
return System.Collections.Generic.IEnumerable<System.Int32>.GetEnumerator();
}
}
public static void Main()
{
int[] obj = new int[7];
RuntimeHelpers.InitializeArray(obj, (RuntimeFieldHandle)/*OpCode not supported: LdMemberToken*/);
int[] source = obj;
IEnumerable<<>f__AnonymousType0<int, int>> enumerable = source.Select(<>c.<>9__0_0 ?? (<>c.<>9__0_0 = <>c.<>9.<Main>b__0_0));
}
[IteratorStateMachine(typeof(<Yield>d__1))]
public static IEnumerable<int> Yield()
{
return new <Yield>d__1(-2);
}
}
[CompilerGenerated]
internal sealed class <PrivateImplementationDetails>
{
[StructLayout(LayoutKind.Explicit, Pack = 1, Size = 28)]
private struct __StaticArrayInitTypeSize=28
{
}
internal static readonly __StaticArrayInitTypeSize=28 572ED8A201DB898C54AEE5E176701DF001029BE8/* Not supported: data(03 00 00 00 01 00 00 00 04 00 00 00 01 00 00 00 05 00 00 00 09 00 00 00 02 00 00 00) */;
}