PluginLoader.CreateFromAssemblyFile fail when dependency is in two packages

Describe the bug Having two packages where one package contain a library that is also in the other package, PluginLoader.CreateFromAssemblyFile when iterating deps file, adding managed libraries.

To Reproduce

EDIT 1/11: Reproduction repo provided in later comment.

Steps to reproduce the behavior:

1. Create a library Lib1 (e.g dotnet new classlib). Package it.
2. Create another library, Lib2, and package it, but include Lib1.dll in that package too.
3. Create an application referencing both packages (e.g dotnet new console). (I used a local feed and a NuGet.config)
4. Load the application with PluginLoader.CreateFromAssemblyFile.

Expected behavior The application load fine and loader resolves what library to use.

Additional context Failure is when AssemblyLoadContextBuilder.AddManagedLibrary tries to add the contained library the second time, causing _managedLibraries.Add(library.Name.Name, library); to raise exception.

Regarding packages, here’s what they would look like if following instructions:

Lib1
  lib\
    lib1.dll

Lib2
  lib\
    lib1.dll
    lib2.dll

And yes, it’s a pretty exotic case. But since NuGet will support multiple libraries in one lib\ hive, these packages exist out there, and you’ll see them fail.

[natemcmaster]

A PR would be great. Here are some of the changes I would make to enable this:

• Don’t throw from AssemblyLoadContextBuilder.AddManagedLibrary when duplicate libraries are added. Internally, create a dictionary which varies by name and version.
• Add two properties to ManagedLibrary
  • public System.Version FileVersion { get; set; } This value should match AssemblyFileVersionAttribute
  • public System.Version AssemblyVersion { get; set; }, maps the version in assembly identity
• When there are assemblies with the same name, resolve the higher assembly version and higher file version if assembly versions match.
• Populate the version info when reading from deps.json (not sure if Microsoft.Extensions.DependencyModel provides API for this or not)

[per-samuelsson]

Since setup is a bit time-consuming, I’ve made you a repro.

Clone this

https://github.com/per-samuelsson/ReproPluginsIssue

and CD into src, and execute Run.bat.

The app depend on those two generated packages (via App1\Nuget.config) and will load itself using PluginLoader.CreateFromAssembly, and you should see it fail.