How to retrieve actual item from HashSet<T>?

I've read this question about why it is not possible, but haven't found a solution to the problem.

I would like to retrieve an item from a .NET HashSet<T>. I'm looking for a method that would have this signature:

/// <summary>
/// Determines if this set contains an item equal to <paramref name="item"/>, 
/// according to the comparison mechanism that was used when the set was created. 
/// The set is not changed. If the set does contain an item equal to 
/// <paramref name="item"/>, then the item from the set is returned.
/// </summary>
bool TryGetItem<T>(T item, out T foundItem);

Searching the set for an item with such a method would be O(1). The only way to retrieve an item from a HashSet<T> is to enumerate all items which is O(n).

I haven't find any workaround to this problem other then making my own HashSet<T> or use a Dictionary<K, V>. Any other idea?

Note:
I don't want to check if the HashSet<T> contains the item. I want to get the reference to the item that is stored in the HashSet<T> because I need to update it (without replacing it by another instance). The item I would pass to the TryGetItem would be equal (according to the comparison mechanism that I've passed to the constructor) but it would not be the same reference.

Solution

What you're asking for was added to .NET a year ago, and was recently added to .NET 4.7.2:

In .NET Framework 4.7.2 we have added a few APIs to the standard Collection types that will enable new functionality as follows.

‘TryGetValue‘ is added to SortedSet and HashSet to match the Try pattern used in other collection types.

The signature is as follows (found in .NET 4.7.2 and above):

    //
    // Summary:
    //     Searches the set for a given value and returns the equal value it finds, if any.
    //
    // Parameters:
    //   equalValue:
    //     The value to search for.
    //
    //   actualValue:
    //     The value from the set that the search found, or the default value of T when
    //     the search yielded no match.
    //
    // Returns:
    //     A value indicating whether the search was successful.
    public bool TryGetValue(T equalValue, out T actualValue);