Missing test coverage for CustomConstantAttribute

[MichalStrehovsky]

This is used in e.g. reflection invoke and Delegate.DynamicInvoke. The below program will print "Hello". We should ideally turn this into a test and add it somewhere around

runtime/src/libraries/System.Runtime/tests/System/DelegateTests.cs

Line 106 in 79ae74f

public static void DynamicInvoke_MissingTypeForDefaultParameter_Succeeds()

.

using System;
using System.Runtime.CompilerServices;


Mine m = MyAttribute.Do;
m.DynamicInvoke(Type.Missing);

delegate void Mine([My] object o);

class MyAttribute : CustomConstantAttribute
{
    public static void Do(object o)
    {
        Console.WriteLine(o);
    }

    public override object Value => "Hello";
}

[SkiFoD]

Hey, I'd love to work with the issue. If you don't mind I will take it.

[MichalStrehovsky]

It's yours! Thank you!

[buyaa-n]

@MichalStrehovsky @SkiFoD seems it is fixed with #49767? Could we close it?

[MichalStrehovsky]

Yup, closing.

[ivanpovazan]

Hello @MichalStrehovsky

I know this is an closed issue but is related to what I am trying to fix for Mono via #75612 .
After looking into code in coreCLR, I am trying to figure out what is the defined behaviour in case when there are multipleCustomConstant (or derived) attributes attached to a parameter.

Based on this comment: https://github.com/dotnet/runtime/blob/79ae74f5ca5c8a6fe3a48935e85bd7374959c570/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeParameterInfo.cs#L311-#L317 and code that follows, it seems coreCLR would handle default value resolution differently when there are more than one CustomConstant attribute attached (depending on their type: DateTime vs decimal).

Do you have any insight on what would be the desired behaviour?

PS I am also planning to improve test coverage for such cases.

[MichalStrehovsky]

Do you have any insight on what would be the desired behaviour?

The defined behavior is basically how CoreCLR implemented it because it has been like that for 20 years.

It also looks like there's a difference in behavior for DefaultValue and RawDefaultValue (one seems to pick the first CustomConstant, the other will pick the last one). Fun. Thanks for looking into it!