Roslyn: Source Generators Not Generating Sources

Created on 9 Nov 2020 · 7Comments · Source: dotnet/roslyn

I am having trouble getting the source generators to run/work. I am not sure what is not working. I have been working on this off and on for several days, and then today when I open the solution it just had worked at some point. Not sure if it was while opening the project or what caused the success. I went and added a new file to create a new source generator and then nothing. Now when I build the project, I get the following warning when building:

warning CS8032: An instance of analyzer SampleSourceGenerators.HelloWorldGenerator cannot be created from C:\Users\daemogar\Source\Repos\BlazorSamples\SampleSourceGenerators\bin\Debug\net5.0\SampleSourceGenerators.dll : Could not load file or assembly 'System.Runtime, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

I have added this project to my sample Blazor app github repo so the issue can be easily duplicated.
Sample Source Generator Project

I created this source generator project, added it to my solution, and modified the associated SampleSourceGenerators.csproj file to be as shown below. I also added the sample HelloWorldGenerator.cs by copy/paste from the online examples. I then went to the project where I wanted to use the generated source and added the modification shown below to the Website.Server.csproj.

I initially was using VSCode 1.51.0, but with source generators, I switched over to using Visual Studio 2019 Preview 6 since I am not aware of source generators working in VSCode yet. I am also using the .NET SDK framework 5.0.100-rc.2.20479.15.

Build Output Window

Build started...
1>------ Build started: Project: SampleSourceGenerators, Configuration: Debug Any CPU ------
1>You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
1>SampleSourceGenerators -> C:\Users\daemogar\Source\Repos\BlazorSamples\SampleSourceGenerators\bin\Debug\net5.0\SampleSourceGenerators.dll
2>------ Build started: Project: WebSite.Server, Configuration: Debug Any CPU ------
2>CSC : warning CS8032: An instance of analyzer SampleSourceGenerators.HelloWorldGenerator cannot be created from C:\Users\daemogar\Source\Repos\BlazorSamples\SampleSourceGenerators\bin\Debug\net5.0\SampleSourceGenerators.dll : Could not load file or assembly 'System.Runtime, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified..
2>CSC : warning CS8032: An instance of analyzer SampleSourceGenerators.HelloWorldGenerator cannot be created from C:\Users\daemogar\Source\Repos\BlazorSamples\SampleSourceGenerators\bin\Debug\net5.0\SampleSourceGenerators.dll : Could not load file or assembly 'System.Runtime, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified..
2>WebSite.Server -> C:\Users\daemogar\Source\Repos\BlazorSamples\SampleHostedApplication\WebSite\Server\bin\Debug\net5.0\WebSite.Server.dll
2>WebSite.Server -> C:\Users\daemogar\Source\Repos\BlazorSamples\SampleHostedApplication\WebSite\Server\bin\Debug\net5.0\WebSite.Server.Views.dll
2>Done building project "WebSite.Server.csproj".
========== Build: 2 succeeded, 0 failed, 3 up-to-date, 0 skipped ==========

SampleSourceGenerators/SampleSourceGenerators.csproj

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

    <PropertyGroup>
        <TargetFramework>net5.0</TargetFramework>
        <LangVersion>preview</LangVersion>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0-5.final" PrivateAssets="all" />
        <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.1" PrivateAssets="all" />
    </ItemGroup>

</Project>

SampleHostedApplication/Website/Server/Website.Server.csproj

<ItemGroup>
    <ProjectReference Include="..\..\..\SampleSourceGenerators\SampleSourceGenerators.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
</ItemGroup>

dotnet --info

.NET SDK (reflecting any global.json):
 Version:   5.0.100-rc.2.20479.15
 Commit:    da7dfa8840

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.100-rc.2.20479.15\

Host (useful for support):
  Version: 5.0.0-rc.2.20475.5
  Commit:  c5a3f49c88

.NET SDKs installed:
  1.0.0-preview1-002702 [C:\Program Files\dotnet\sdk]
  1.0.0-preview2-003121 [C:\Program Files\dotnet\sdk]
  1.0.0-preview2-003131 [C:\Program Files\dotnet\sdk]
  1.0.1 [C:\Program Files\dotnet\sdk]
  1.0.2 [C:\Program Files\dotnet\sdk]
  1.0.4 [C:\Program Files\dotnet\sdk]
  1.1.0 [C:\Program Files\dotnet\sdk]
  2.0.2 [C:\Program Files\dotnet\sdk]
  2.0.3 [C:\Program Files\dotnet\sdk]
  2.1.2 [C:\Program Files\dotnet\sdk]
  2.1.4 [C:\Program Files\dotnet\sdk]
  2.1.101 [C:\Program Files\dotnet\sdk]
  2.1.103 [C:\Program Files\dotnet\sdk]
  2.1.104 [C:\Program Files\dotnet\sdk]
  2.1.200 [C:\Program Files\dotnet\sdk]
  2.1.201 [C:\Program Files\dotnet\sdk]
  2.1.202 [C:\Program Files\dotnet\sdk]
  2.1.400 [C:\Program Files\dotnet\sdk]
  2.1.401 [C:\Program Files\dotnet\sdk]
  2.1.402 [C:\Program Files\dotnet\sdk]
  2.1.403 [C:\Program Files\dotnet\sdk]
  2.1.500 [C:\Program Files\dotnet\sdk]
  2.1.502 [C:\Program Files\dotnet\sdk]
  2.1.503 [C:\Program Files\dotnet\sdk]
  2.1.504 [C:\Program Files\dotnet\sdk]
  2.1.505 [C:\Program Files\dotnet\sdk]
  2.1.507 [C:\Program Files\dotnet\sdk]
  2.1.508 [C:\Program Files\dotnet\sdk]
  2.1.509 [C:\Program Files\dotnet\sdk]
  2.1.512 [C:\Program Files\dotnet\sdk]
  2.1.514 [C:\Program Files\dotnet\sdk]
  2.1.517 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.604 [C:\Program Files\dotnet\sdk]
  2.1.700 [C:\Program Files\dotnet\sdk]
  2.1.801 [C:\Program Files\dotnet\sdk]
  3.1.300 [C:\Program Files\dotnet\sdk]
  3.1.302 [C:\Program Files\dotnet\sdk]
  3.1.402 [C:\Program Files\dotnet\sdk]
  5.0.100-preview.8.20417.9 [C:\Program Files\dotnet\sdk]
  5.0.100-rc.1.20452.10 [C:\Program Files\dotnet\sdk]
  5.0.100-rc.2.20479.15 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-preview.8.20414.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-rc.1.20451.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-rc.2.20475.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 1.0.0-rc2-3002702 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 1.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.3-servicing-26724-03 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-preview.8.20407.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-rc.1.20451.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-rc.2.20475.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-preview.8.20411.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-rc.1.20452.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-rc.2.20475.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Area-Compilers Bug New Feature - Source Generators

Source

daemogar

👍1

Most helpful comment

<TargetFramework>net5.0</TargetFramework>

Source generators _must_ target netstandard2.0.

sharwell on 9 Nov 2020

🎉2 👍2

All 7 comments

<TargetFramework>net5.0</TargetFramework>

Source generators _must_ target netstandard2.0.

sharwell on 9 Nov 2020

🎉2 👍2

@jasonmalinowski @chsienki this seems like a case where the wrong error is getting reported for an incorrectly targeted source generator.

sharwell on 9 Nov 2020

The project has been updated to use netstandard2.0 and the error is gone; however, the generated source does not appear to be able, nor do I see it in the obj/bin folders (when I used net5.0 I saw the generated file in the obj folder).

daemogar on 10 Nov 2020

I did more testing last night, and it appears that the sources are being generated (basically). Changes or new sources are not available until closing and reopening Visual Studio.

Once restarted, I have access to the generated source like in all the samples. I can [control]-[click] on it and it takes me to the generated source and I can see it even after making a change to the generator, it appears to update (most of the time, it is not reliable). That being said, it still requires me to relaunch Visual Studio to use the latest source.

Example Experience/Scenario

I have a generator that makes a class SampleClass with a static method SampleMethod() and all it does is Debug.WriteLine("test"); It never shows up in Visual Studio but I can tell it generates cause I will see issues in the output window. I have to clean the solution and build the project, close and reopen Visual Studio, and most of the time, the code is available. Now, I can use it in my project. All basically well. I decide to change the text "test" to "something else". I cannot tell if it worked or not, but clean and build again just in case (I have also tried skipping this step with the same results). When I [control]-[click] on the method where I use it, it shows the change, but when I run the code, it has not changed; however, when I restart Visual Studio it works just fine (the change is realized).

daemogar on 10 Nov 2020

Source generators must target netstandard2.0.

So we outright blocked things targeting the .NET Framework; @chsienki I believe the block doesn't block .NET Core referencing ones, albeit it won't really work in VS for Windows?

I am not aware of source generators working in VSCode yet.

The experience is a bit rougher there, but as long as you have the latest C# Extension installed you should have basics working fine.

That being said, it still requires me to relaunch Visual Studio to use the latest source.

Yeah, the one limitation we have in VS due to .NET limitations is once we've loaded your generator into our process, we don't have a way to unload it at this point. #48083 is another example of that too.

jasonmalinowski on 10 Nov 2020

Experiencing the same problem. The source generator is definitely executed (verified with Debugger.Launch()), but the file is never generated. I am using the hello world example from here. Even searched the entire disk but couldn't find a file generated with the hint I gave it. Is there anything I am missing?

Visual Studio: Version 16.8.3
SDK: 5.0.101