Duplicate dependancies causes an Ambiguous reference compilation error?

[jeremyosterhoudt]

A college an myself are attempting to convert an old project that compiled Apache Calcite and a few other libraries using an older version of IKVM to the latest version of IKVM. I'm not sure if we have run into a bug or if we are missing a property setting in our project. However, when we compile the project we end up with the following error:

error CS0433: The type 'Range' exists in both 'com.google.common, Version=31.1.0.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' and 'io.grpc, Version=1.9.0.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' [/dev/calcite-ikvm/CalciteIKVM/CalciteIKVM/CalciteIKVM.csproj]

Here the example project I'm using to duplicate the error we get on the larger project:

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
        <MavenAdditionalRepositories>$(MavenAdditionalRepositories);myrepo=https://repository.jboss.org/nexus/content/groups/public</MavenAdditionalRepositories>
    </PropertyGroup>
    
    <ItemGroup>
        <MavenReference Include="org.apache.calcite:calcite-core" Version="1.34.0" />
        <MavenReference Include="com.clickhouse:clickhouse-jdbc" Version="0.4.6" />
        <MavenReference Include="javax.jms:jms" Version="1.1" />
    </ItemGroup>

    <ItemGroup>
      <PackageReference Include="IKVM" Version="8.7.1" />
      <PackageReference Include="IKVM.Maven.Sdk" Version="1.6.1" />
    </ItemGroup>
</Project>

using Range = com.google.common.collect.Range;

namespace CalciteIKVM;

public class Class1
{
    public void Test()
    {
        var range = Range.singleton(10);
        var x = range.hasLowerBound() ? range.lowerEndpoint() : range.upperEndpoint();
    }
}

We are testing on an Apple Silicon based Mac. We've not tried on other architectures.

[wasabii]

That's a CSharp error, not an IKVM error. Your references compiled fine. There are however types with the same name in both assemblies. Chances are the are types with the same name in both original JARs. Why? I do not know. Check, though.

[jeremyosterhoudt]

In the case that two packages reference the same dependency with different versions, is that handled by default with the IKVM.Maven.Sdk or would the C# project need to reference the specific dependency and version as maven package?

[wasabii]

It isn't two packages referencing the same dependency with different versions. It's two packages referencing two different dependencies with the same classes. Hence the error: The type 'Range' exists in both 'com.google.common, Version=31.1.0.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' and 'io.grpc, Version=1.9.0.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' [/dev/calcite-ikvm/CalciteIKVM/CalciteIKVM/CalciteIKVM.csproj]

The type, Range, is in both 'com.google.common', and also in 'io.grpc'. Two different packages. One class.

[jeremyosterhoudt]

Yes, I understand that. The part that is confusing is these two packages can be brought into a Java project using gradle or maven and the issue will not be present. The project simple imports com.google.common.collect.Range and everything is fine. In C# because of the namespace collision it seems as if the references need to be brought in individually (which is fine).

[wasabii]

Well, the issue can bepresent, in that you have duplicate overlapping class names on your classpath in Java, and if you attempted to compile code against both of these JAR files at the same time, javac.exe would throw an error regarding the duplicate class name. When you type new Range in Java, it wouldn't know which Range you were talking about.

So here's what I've found: https://github.com/ClickHouse/clickhouse-java/tree/main/third-party-libraries/io.grpc

There's a package com.clickhouse:io.grpc in Maven, dependended on by the clickhouse stuff. It appears to be a repackage of gRPC, but configured differently (with JPMS support). So yeah, it overlaps. Which one do you intend to use?

In Java, at RUNTIME, it'll pick whichever one appears FIRST on the classpath. As opposed to compile time, where it'll error. But you still have control over that, even with Maven, or you can just let Maven randomlly pick one, so it's still sort of up to you.

Once you pick which Range class you want to use, what you'll want to do is add an Alias to it. Which we will need some doctoring of your project file for.

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/namespaces#148-qualified-alias-member

[jeremyosterhoudt]

I was able to solve it using an assembly alias like the following in the csproj:

<Target Name="ChangeAliasesOfStrongNameAssemblies" BeforeTargets="FindReferenceAssembliesForReferences;ResolveReferences">
    <ItemGroup>
        <ReferencePath Condition="'%(FileName)' == 'com.google.common'">
            <Aliases>GoogleCommon</Aliases>
        </ReferencePath>
    </ItemGroup>
</Target> 

Thanks for the information. It was helpfully in trying to figure out how to resolve the conflicted namespace issue.

[wasabii]

Np. That was my goal, to sort of walk you through to that answer.

What we are missing though is built in support on IKVM.Maven for setting Aliases.