Blazor: EditContext fieldstate tracking falls apart when model implements GetHashCode

Describe the bug

When a model implements GetHashCode, the _fieldState dictionary within EditContext continually adds to it's collection for the same field, effectively breaking the field-state logic.

To Reproduce

In my case, I used a protocol buffer to generate a simple C# class. Here's a gist: https://gist.github.com/aaronhudon-ts/6f9b079014115f539feef9b599a2c14d

• Put a breakpoint in EditContext.cs GetFieldState. Start changing values in fields. You will notice that the call to TryGetValue always fails due to the underlying GetHashCode call of the FieldIdentifier.

[pranavkm]

Thanks for the issue report @aaronhudon-ts. We'll look in to how to resolve this soon.

[pranavkm]

We might be able to address this by using https://docs.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.runtimehelpers.gethashcode?view=netframework-4.8#remarks

Thanks for the issue report @aaronhudon-ts. We'll look in to how to resolve this soon.

Thanks @pranavkm If you can suggest any workaround for the time being that does not require me to abandon protobufs as the data model, it would be most appreciated. I'm targeting a production release by the end of the month.

[pranavkm]

Does using a derived type as a model that overrides GetHashCode work? Looking at EditContext \ FieldIdentifier, nothing immediately jumps at me that would work as a suitable work around.

@pranavkm Ok, assuming I can override GetHashCode in the protobuf generated code (I think it's possible with partials), what would the fix be?

[pranavkm]

public override int GetHashCode() => RuntimeHelpers.GetHashCode(this);

public override bool Equals(object other) => ReferenceEquals(this, other);

public override int GetHashCode() => RuntimeHelpers.GetHashCode(this);

public override bool Equals(object other) => ReferenceEquals(this, other);

Thanks! I'll give it a try. Would be awesome to summon @jskeet for feedback on any potential side effects of doing this in the C# proto runtime

[jskeet]

Not sure where the proto runtime comes in here - protobuf messages are explicitly equal by value.

The generated C# for the protobuf implements GetHashCode (e.g. like below). What are the implications of changing the generated code to be like @pranavkm suggests
E.g.

` ``
public override int GetHashCode() {
int hash = 1;
if (String1.Length != 0) hash ^= String1.GetHashCode();
if (String2.Length != 0) hash ^= String2.GetHashCode();
if (Number1 != 0D) hash ^= pbc::ProtobufEqualityComparers.BitwiseDoubleEqualityComparer.GetHashCode(Number1);
if (Number2 != 0D) hash ^= pbc::ProtobufEqualityComparers.BitwiseDoubleEqualityComparer.GetHashCode(Number2);
if (_unknownFields != null) {
hash ^= _unknownFields.GetHashCode();
}
return hash;
}