[6.0.100-alpha.1.21064.42] Replychsharp get error CS0009: Metadata file 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\6.0.0-alpha.1.21063.13\System.IO.Compression.Native.dll' could not be opened

[jiangzeng01]

Application Name: replay-csharp
OS: Windows 10 RS5
CPU: X64
.NET Build Number: 6.0.100-alpha.1.21064.42
App Source: replay-csharp.zip
DevDiv bug: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1266457

Repro steps:

1. Download app source above and 'cd replay-csharp\Replay'
2. dotnet run
3. Type “Console.Write("hellow world")” in app window, and click Enter.

Expected Result:
print "hello world"

Actual Result:
error CS0009: Metadata file 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\6.0.0-alpha.1.21063.13\System.IO.Compression.Native.dll' could not be opened -- PE image doesn't contain managed metadata.

Findings:
When debugging the source code in Visual Studio 2019, below logs print in Output window.

'Replay.exe' (CoreCLR: clrhost): Loaded 'C:\.NETCoreUpgradeApps\replay-csharp\Replay\bin\Debug\netcoreapp3.1\win-x64\System.Globalization.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'Replay.exe' (CoreCLR: clrhost): Loaded 'C:\.NETCoreUpgradeApps\replay-csharp\Replay\bin\Debug\netcoreapp3.1\win-x64\System.AppContext.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Exception thrown: 'Microsoft.CodeAnalysis.Scripting.CompilationErrorException' in Microsoft.CodeAnalysis.Scripting.dll

@dotnet-actwx-bot

[ericstj]

This app is doing the following:

        public MetadataReference[] GetDefaultAssemblies()
        {
            var installation = dotNetInstallationLocator.GetReferenceAssemblyPath() ?? throw new InvalidOperationException("Could not find dotnet installation");

            // get SDK DLLs
            var implementationPath = Path.Combine(installation.BasePath, "shared", "Microsoft.NETCore.App", installation.Version);
            // get xml documentation for those DLLs
            var latestRef = io
                .GetDirectories(
                    Path.Combine(installation.BasePath, "packs", "Microsoft.NETCore.App.Ref")
                )
                .Last();
            var referencePath = Path.Combine(latestRef, "ref");

            return GroupDirectoryContentsIntoAssemblies(
                    io.GetFilesInDirectory(implementationPath, "*.dll", SearchOption.AllDirectories)
                    .Union(io.GetFilesInDirectory(referencePath, "*.xml", SearchOption.AllDirectories))
                )
                .Where(assembly => assembly.AssemblyName.StartsWith("System"))
                .Select(assembly => io.CreateMetadataReferenceWithDocumentation(assembly))
                .ToArray();
        }

It "noticed" that the dll name changed from clrcompression.dll to System.IO.Compression.Native.dll which was done by @VSadov in 99f3f55 (#45713).

What this app is doing is incorrect. It's examining the .NETCore installation directory and using implementation assemblies for compilation. It assumes everything that starts with "System.*" will be managed assembly.

It looks like it already understands where the reference assemblies live. It should just use those for compilation.

@waf it looks like this is your project. https://github.com/waf/replay-csharp/blob/e433ad0da9c637d44ebe79ef13b25a3a89b27c35/Replay.Services/AssemblyLoading/DotNetAssemblyLocator.cs#L20

Is there any reason you have to use implementation assemblies here?

[waf]

@ericstj Hi, appreciate you taking a look into this. I'm sure the app is at fault here, rather than the runtime. As background, the app is a REPL for C#, and heavily uses the Roslyn APIs.

It ultimately needs the assemblies to pass into the following two Roslyn APIs:

1. The Roslyn ScriptOptions - Runtime evaluation with the Roslyn Scripting APIs (e.g. CSharpScript). This drives the core of the REPL evaluation.
2. The Roslyn ProjectInfo, for use with Roslyn Workspaces. This drives all the syntax highlighting, code completion, method documentation, and miscellaneous other services that require workspaces / projects.

I initially tried using the reference assemblies, and while that worked for the workspace APIs (item 2, above), it did not work for the scripting APIs (item 1, above). It failed with the error: Predefined type 'System.Object' is not defined or imported even without the System prefix filtering. The only way I was able to get the scripting API to work was by using the implementation assemblies.

I'm sure there's a better way to do this, but I was mostly figuring this out by trial and error.