Consider adding a new reflection API to get field values of an Enum

The trimmer doesn't trim Enum fields. As mentioned in the comment here, it would make sense to have a separate API that doesn't require DynamicallyAccessedMembers annotation to get Enum fields. That would prevent suppressing the warning as done here when getting Enum fields.

Can't NativeAOT not generate reflection info for such fields?

get field values of an Enum

Note that we have added trim and AOT friendly ways to get values of an Enum: Enum.GetValuesAsUnderlyingType - #72498.

The specific case in EnumConverter wants the field values presented as FieldInfos. Fetching enum values as FieldInfos is quite inefficient, but it is required here because of pre-existing public surface.

A new API can look like this:

public class Enum
{
    [UnconditionalSuppressMessage("Trimming", "IL2075:", Justification = "Trimmer does not trim Enums")]
    public static FieldInfo[] GetValuesAsFieldInfos(Type enumType)
    {
        ArgumentNullException.ThrowIfNull(enumType);

        if (!enumType.IsEnum)
            throw new ArgumentException(SR.Arg_MustBeEnum, "enumType")

       return enumType.GetFields(BindingFlags.Public | BindingFlags.Static);
    }

The question is whether fetching enum values as FieldInfos is common enough to warrant a new public API. I think we would want to see at least one or two additional cases from real-world code where this API can be used.

The question is whether fetching enum values as FieldInfos is common enough to warrant a new public API.

Here's another use case:

#97737

There we need to get the EnumMemberAttribute on the Field of an Enum.

The specific case in EnumConverter wants the field values presented as FieldInfos. Fetching enum values as FieldInfos is quite inefficient, but it is required here because of pre-existing public surface.

The case in EnumConverter doesn't directly expose the FieldInfos but does check for [Browseable] attribute on the FieldInfo, so a new API is necessary here.

However, the case in EventSource could use Enum.GetValuesAsUnderlyingType() instead of FieldInfos as the FieldInfos used there are used temporarily + privately and do not check for the [Browseable] attribute.

Moving to V10; priority appears low here (removing a couple cases of UnconditionalSuppressMessage).

Here's one more hit on the same scenario:

https://github.com/microsoft/OpenAPI.NET/pull/1717/files#diff-c59c9153ccf5e00142826d1c5e4d3d92470aac0bc740a302a23557432141277cR29

Getting the DisplayAttribute of an enum field.

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Consider adding a new reflection API to get field values of an Enum #100592

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Consider adding a new reflection API to get field values of an Enum #100592

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MichalPetryka commented on Apr 3, 2024

jkotas commented on Apr 3, 2024

eerhardt commented on Apr 3, 2024

steveharter commented on Jul 22, 2024

eerhardt commented on Jul 22, 2024

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