[API Proposal]: Interlocked.Or/And for enums

[MihaZupan]

Background and motivation

#65184 made it possible to simplify code around Exchange/CompareExchange, but when dealing with enums you're still forced to use unsafe casts back and forth.

A few examples: https://grep.app/search?f.repo=dotnet%2Fruntime&regexp=true&q=Interlocked%5C.%28%3F%3AOr%7CAnd%29%5C%28ref+Unsafe%5C.As

API Proposal

namespace System.Threading;

public static class Interlocked
{
    // Existing naming:
    // public static long Or(ref long location1, long value);
    // public static T Exchange<T>(ref T location1, T value);

    public static T Or<T>(ref T location1, T value) where T : struct, Enum;
    public static T And<T>(ref T location1, T value) where T : struct, Enum;
}

API Usage

runtime/src/libraries/System.Private.Uri/src/System/Uri.cs

Lines 207 to 208 in 8f4365a

	Debug.Assert(sizeof(Flags) == sizeof(ulong));
	Interlocked.Or(ref Unsafe.As<Flags, ulong>(ref _flags), (ulong)flags);

becomes

Interlocked.Or(ref _flags, flags); 

Alternative Designs

Exchange/CompareExchange also have overloads for byte/sbyte/ushort/short.
Without the where T : Enum constraint, we could make them "just work" with the generic overload. Otherwise we might want to add those overloads too at some point.
But not having it constrained would also bring in questions like whether float/double should be supported.

namespace System.Threading;

public static class Interlocked
{
    public static T Or<T>(ref T location1, T value);
    public static T And<T>(ref T location1, T value);
}

Risks

No response

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[jkotas]

where T : Enum;

where TEnum : struct, Enum to block Enum parent type.

[huoyaoyuan]

So now we will have Interlocked.And/Or for generic enum, but no normal by-value generic one.

[MihaZupan]

Yeah I mentioned that in the alternative designs section, we could either add all the overloads we care about for smaller numbers, or drop the generic constraint and throw at runtime for invalid types like we do for {Compare}Exchange.