KeyedService.AnyKey -> not working correctly

[waszakCeneo]

Description

Method GetKeyedServices should allow you to get all keyed services.
Instead of adding correct override for that there was created this hack called "KeyedService.AnyKey"
The issues with this hack is that it doesn't work as intended. You would assume that its gonna return services for any key.
But no instead you have to name them the same.

Because this is confusing. I would propose adding just "provider.GetKeyedServices();" and remove AnyKey because it doesn't work as intended.

Reproduction Steps

services.AddKeyedSingleton<IMyType, MyType1>(typeof(MyType1).ToString());
services.AddKeyedSingleton<IMyType, MyType2>(typeof(MyType2).ToString());

access:
var list = provider.GetKeyedServices<IMyType>(KeyedService.AnyKey) //  empty list

Expected behavior

Returns both services

Actual behavior

Returns empty list

Regression?

No response

Known Workarounds

services.AddKeyedSingleton<IMyType, MyType1>(KeyedService.AnyKey);
services.AddKeyedSingleton<IMyType, MyType2>(KeyedService.AnyKey);

access:
var list = provider.GetKeyedServices<IMyType>(KeyedService.AnyKey) // returns both

Configuration

No response

Other information

No response

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-extensions-dependencyinjection
See info in area-owners.md if you want to be subscribed.

[stephentoub]

This prints 2 on .NET 9:

using Microsoft.Extensions.DependencyInjection;

ServiceCollection sc = new();
sc.AddKeyedSingleton<IMyType, MyType1>(typeof(MyType1).ToString());
sc.AddKeyedSingleton<IMyType, MyType2>(typeof(MyType2).ToString());
IServiceProvider provider = sc.BuildServiceProvider();

var list = provider.GetKeyedServices<IMyType>(KeyedService.AnyKey).ToList();
Console.WriteLine(list.Count);

interface IMyType { }
class MyType1 : IMyType { }
class MyType2 : IMyType { }

[waszakCeneo]

Doesn't work on .net8

[stephentoub]

Doesn't work on .net8

Correct.
#91466 (comment)
#95582
#100105

[stephentoub]

cc: @benjaminpetit, @steveharter
#95853