[Bug]: Cannot go to definition of source-generated type

[just-ero]

Version Used

• Compiler version: '4.9.0-1.23530.4 (79d1884)'
• VSCode: 1.84.2, 1a5daa3a0231a0fbba4f14db7ec463cf99d7768e, x64
• C# extension: v2.10.28, C# Dev Kit extension: v1.1.9

Steps to Reproduce

A minimal repro can be found at the end of this issue.

1. Create or open any C# project.
2. Add a package reference to any package which source-generates types.
3. Attempt to navigate to the definition of any of those types.

Expected Behavior

The navigation to the definition succeeds.

Actual Behavior

The navigation fails with an error message from the C# extension similar to the one below (the URI will of course differ):

[Error - 4:33:49 PM] [LanguageServerHost] System.UriFormatException: Failed create URI from 'PolySharp.SourceGenerators\PolySharp.SourceGenerators.PolyfillsGenerator\System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute.g.cs'; original string: 'PolySharp.SourceGenerators\PolySharp.SourceGenerators.PolyfillsGenerator\System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute.g.cs'
 ---> System.UriFormatException: Invalid URI: The format of the URI could not be determined.
   at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind, UriCreationOptions& creationOptions)
   at System.Uri..ctor(String uriString, UriKind uriKind)
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateAbsoluteUri(String absolutePath) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 178
   --- End of inner exception stack trace ---
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.CreateAbsoluteUri(String absolutePath) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 186
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.<TextSpanToLocationAsync>g__ConvertTextSpanToLocation|30_0(Document document, TextSpan span, Boolean isStale, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 477
   at Microsoft.CodeAnalysis.LanguageServer.ProtocolConversions.TextSpanToLocationAsync(Document document, TextSpan textSpan, Boolean isStale, Nullable`1 context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs:line 442
   at Microsoft.CodeAnalysis.LanguageServer.Handler.AbstractGoToDefinitionHandler.GetDefinitionAsync(TextDocumentPositionParams request, Boolean typeOnly, RequestContext context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Handler/Definitions/AbstractGoToDefinitionHandler.cs:line 61
   at Microsoft.CommonLanguageServerProtocol.Framework.QueueItem`3.StartRequestAsync(TRequestContext context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Microsoft.CommonLanguageServerProtocol.Framework/QueueItem.cs:line 124
[Error - 4:33:49 PM] Request textDocument/definition failed.
  Message: Failed create URI from 'PolySharp.SourceGenerators\PolySharp.SourceGenerators.PolyfillsGenerator\System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute.g.cs'; original string: 'PolySharp.SourceGenerators\PolySharp.SourceGenerators.PolyfillsGenerator\System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute.g.cs'
  Code: -32000 
[object Object]

---

Minimal repro

MyProject.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <LangVersion>9.0</LangVersion>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="PolySharp" Version="1.13.2" />
  </ItemGroup>

  <PropertyGroup>
    <PolySharpIncludeRuntimeSupportedAttributes>true</PolySharpIncludeRuntimeSupportedAttributes>
  </PropertyGroup>

</Project>

Class1.cs

namespace MyProject
{
    public class Class1
    {
        // Hovering over this attribute and hitting `Ctrl` shows a Visual Studio Code pop-up saying
        // 'Request textDocument/definition failed.' and does not allow navigation.
        [MemberNotNullWhen(true)]
        public bool Foo { get; }
    }
}

[davidwengier]

FYI @jasonmalinowski

Not sure you have another tracking issue to dupe this against for #68771

[jasonmalinowski]

I think dotnet/vscode-csharp#6426 is the tracking bug.