Source generators, how to debug?

[b-straub]

How can a "Source generator" be debugged?

• where to find the generated output file as mentioned in the section "Output files" from Source Generators? For now I store the generated results myself.

• is there a way to set breakpoints inside the generator?

[b-straub]

Found the answers to one of my questions:

• is there a way to set breakpoints inside the generator?

When invoked by CSharpGeneratorDriver e.g. during Unit testing, the generator code can be debugged.

[danielcrenna]

@b-straub How are you properly creating a testable SourceGeneratorContext?

[b-straub]

@danielcrenna

Please see my test repository for an example BlazorSourceGeneratorTests

[aalmada]

I'm porting my project from using Uno.SourceGeneration to the new source generators. Uno outputs the generated files exactly as proposed for source generators and I'm missing it.

[danielcrenna]

The response from Directory.GetCurrentDirectory() returns the consuming project folder, so it’s easy to emit a string builder to both Roslyn and a text file. I do this to spot check output.

On Mon, May 18, 2020 at 4:58 PM Antão Almada [email protected] wrote:

I'm porting my project from using Uno.SourceGeneration https://github.com/unoplatform/Uno.SourceGeneration to new source generators. Uno outputs the generated files exactly as proposed for source generators https://github.com/dotnet/roslyn/blob/master/docs/features/source-generators.md#output-files and I'm missing it.

[aalmada]

@danielcrenna I added the following to the beginning of my Execute():

        // create a folder to serialize the generated source for debugging
        string? generatedPath = null;
#if DEBUG
        // place it inside obj so that source is not added to the project
        generatedPath = Path.Combine("obj", "Debug", "Generated");
        // delete source generated by previous build
        if (Directory.Exists(generatedPath))
                Directory.Delete(generatedPath, true);
        Directory.CreateDirectory(generatedPath);
#endif

and, for each generated file:

        var hitName = $"{containerClass.OriginalDefinition.MetadataName}.{extendedType.OriginalDefinition.MetadataName}.cs";
        var source = builder.ToString();
#if DEBUG
        File.WriteAllText(Path.Combine(generatedPath, hitName), source);
#endif
        context.AddSource(hitName, SourceText.From(source, Encoding.UTF8));

Still, it would be nice to have an official solution.

[danielcrenna]

@aalmada Oh, that is a much nicer way than I'm doing it, thanks for sharing.

[pakrym]

Take a look at this target: https://github.com/pakrym/jab/blob/main/src/Jab.Tests/Jab.Tests.csproj#L33

It generates the https://github.com/pakrym/jab/blob/main/src/Jab/Properties/launchSettings.json file that mimicks the csc invocation and allows for F5 debugging.

[opekope2]

I debug my source generators by attaching vscode to the build process Add this code to the source generator:

using System;
using System.Diagnostics;
using System.Threading;

Console.Error.WriteLine($"PID: {Process.GetCurrentProcess().Id}");
while (!Debugger.IsAttached)
{
    Thread.Sleep(100);
}