This attribute hides methods and types marked by it in the error message stacktraces. It is used extensively in the CoreLib to e.g. hide implementation details of async methods that are always the same and just add clutter to the error messages.

It appears to be a very useful attribute, particular as System.ThrowHelper is internal, this would be invaluable for user-written throw helper types to keep the best possible exception semantics while still having the advantages of a throw helper. It could be abused, but not really in a "breaking" way, just using it stupidly could make debugging a little harder, so unless there is something I am really missing I cannot see a strong case against making it public.

Proposed API

namespace System.Diagnostics
{
    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method | AttributeTargets.Constructor | AttributeTargets.Struct, Inherited = false)]
    public sealed class StackTraceHiddenAttribute : Attribute
    {
        public StackTraceHiddenAttribute() { }
    }
}