更新
这个答案的代码已经成为GitHub上的一个存储库：Undefault.NET on GitHub
Steven给出了关于为什么会按照这种方式工作的很好的解释。我不认为有解决Object.Equals情况的方法。但是，
我发现了一种通过使用反射配置默认相等比较器来解决EqualityComparer<T>.Default问题的方法。
这个小技巧只需要在应用程序生命周期内执行一次。启动时执行这个操作是个好时机。使它工作的代码行是：
DefaultComparisonConfigurator.ConfigureEqualityComparer<Type>(new HackedTypeEqualityComparer())
执行该代码后，
EqualityComparer<Type>.Default.Equals(t2, t1))将产生与
EqualityComparer<Type>.Default.Equals(t1,t2))相同的结果（在您的示例中）。
支持基础设施代码包括：
1. 自定义IEqualityComparer<Type>实现
此类按您希望其行为处理等式比较。
public class HackedTypeEqualityComparer : EqualityComparer<Type> {
public override bool Equals(Type one, Type other){
return ReferenceEquals(one,null)
? ReferenceEquals(other,null)
: !ReferenceEquals(other,null)
&& ( (one is TypeDelegator || !(other is TypeDelegator))
? one.Equals(other)
: other.Equals(one));
}
public override int GetHashCode(Type type){ return type.GetHashCode(); }
}
2. 一个Configurator类
这个类使用反射来配置EqualityComparer<T>.Default的基础字段。此外，该类还公开了一种机制来操纵Comparer<T>.Default的值，并确保配置实现的结果是兼容的。还有一种方法可以将配置恢复到框架默认值。
public class DefaultComparisonConfigurator
{
static DefaultComparisonConfigurator(){
Gate = new object();
ConfiguredEqualityComparerTypes = new HashSet<Type>();
}
private static readonly object Gate;
private static readonly ISet<Type> ConfiguredEqualityComparerTypes;
public static void ConfigureEqualityComparer<T>(IEqualityComparer<T> equalityComparer){
if(equalityComparer == null) throw new ArgumentNullException("equalityComparer");
if(EqualityComparer<T>.Default == equalityComparer) return;
lock(Gate){
ConfiguredEqualityComparerTypes.Add(typeof(T));
FieldFor<T>.EqualityComparer.SetValue(null,equalityComparer);
FieldFor<T>.Comparer.SetValue(null,new EqualityComparerCompatibleComparerDecorator<T>(Comparer<T>.Default,equalityComparer));
}
}
public static void ConfigureComparer<T>(IComparer<T> comparer){
if(comparer == null) throw new ArgumentNullException("comparer");
if(Comparer<T>.Default == comparer) return;
lock(Gate){
if(ConfiguredEqualityComparerTypes.Contains(typeof(T)))
FieldFor<T>.Comparer.SetValue(null,new EqualityComparerCompatibleComparerDecorator<T>(comparer,EqualityComparer<T>.Default));
else
FieldFor<T>.Comparer.SetValue(null,comparer);
}
}
public static void RevertConfigurationFor<T>(){
lock(Gate){
FieldFor<T>.EqualityComparer.SetValue(null,null);
FieldFor<T>.Comparer.SetValue(null,null);
ConfiguredEqualityComparerTypes.Remove(typeof(T));
}
}
private static class FieldFor<T> {
private const string FieldName = "defaultComparer";
private const BindingFlags FieldBindingFlags = BindingFlags.NonPublic|BindingFlags.Static;
static FieldInfo comparer, equalityComparer;
public static FieldInfo Comparer { get { return comparer ?? (comparer = typeof(Comparer<T>).GetField(FieldName,FieldBindingFlags)); } }
public static FieldInfo EqualityComparer { get { return equalityComparer ?? (equalityComparer = typeof(EqualityComparer<T>).GetField(FieldName,FieldBindingFlags)); } }
}
}
3. 兼容的IComparer<T>实现
这基本上是IComparer<T>的装饰器，确保在注入EqualityComparer<T>时，Comparer<T>和EqualityComparer<T>之间的兼容性。它确保配置的IEqualityComparer<T>实现认为相等的任何两个值始终具有比较结果0。
public class EqualityComparerCompatibleComparerDecorator<T> : Comparer<T> {
public EqualityComparerCompatibleComparerDecorator(IComparer<T> comparer, IEqualityComparer<T> equalityComparer){
if(comparer == null) throw new ArgumentNullException("comparer");
if(equalityComparer == null) throw new ArgumentNullException("equalityComparer");
this.comparer = comparer;
this.equalityComparer = equalityComparer;
}
private readonly IComparer<T> comparer;
private readonly IEqualityComparer<T> equalityComparer;
public override int Compare(T left, T right){ return this.equalityComparer.Equals(left,right) ? 0 : comparer.Compare(left,right); }
}
