CSharp on dotnet10 - rc2 not finalizing anymore (macos and linux)

[sandrohanea]

Running github/codeql-action/analyze on macos with dotnet 8, dotnet9 and dotnet 10 installed is failing to detect the build.

Same configuration is working on windows.

Same configuration worked before dotnet 10-rc2 was released (rc1 was working fine).

Error:

 Encountered a fatal error while running "/Users/runner/hostedtoolcache/CodeQL/2.23.2/arm64/codeql/codeql database finalize --finalize-dataset --threads=3 --ram=6144 /Users/runner/work/_temp/codeql_databases/csharp". Exit code was 32 and last log line was: CodeQL detected code written in C# but this run didn't build any of it, or CodeQL could not process any of it. Ensure that you have provided manual build steps (see https://docs.github.com/en/code-security/code-scanning/creating-an-advanced-setup-for-code-scanning/codeql-code-scanning-for-compiled-languages#about-specifying-build-steps-manually) for C# between the 'init' and 'analyze' Actions, and check the workflow run logs (see https://docs.github.com/en/actions/monitoring-and-troubleshooting-workflows/using-workflow-run-logs). For more information, review our troubleshooting guide at https://gh.io/troubleshooting-code-scanning/no-source-code-seen-during-build . See the logs for more details.

Example of run: https://github.com/sandrohanea/whisper.net/actions/runs/18525877235/job/52796706902

Any idea what can cause this?

Thank you!

[mbg]

Thanks for opening this issue!

A few points:

• We don't claim to support any pre-release versions of languages / frameworks, so the fact that the analysis worked with dotnet 10-rc1 was pure luck! You can find the list of supported languages and frameworks at https://codeql.github.com/docs/codeql-overview/supported-languages-and-frameworks/
• .NET 10 should be supported by CodeQL at some point after it is fully released.
• In general, the issue means that CodeQL didn't observe any code getting compiled. You should check that your custom build command rebuilds the entire project from scratch (and e.g. doesn't cache anything between builds). It's also possible that there is some change in dotnet 10-rc2 that breaks compatibility with CodeQL.
• Re-run the workflow with debugging enabled to get extra output during the analysis to get a better idea of what's going. A copy of the CodeQL database and logs will also be uploaded as a workflow artifact.

[sandrohanea]

Thank you for the quick response @mbg !

I re-ran the workflow with debugging enabled and here is the result: https://github.com/sandrohanea/whisper.net/actions/runs/18525877235/job/52804525544

I understand that dotnet 10 is not fully released and this can be the reason for this behaviour. It's intersting as the Windows build finishes correctly with both dotnet 10 RC1 and RC2, only the macos is failing.

I want the library to be ready for day 0 of the dotnet release, so will most likely just disable codeql for macos for now. Looking forward for the fix.

[gimlichael]

Same problem for my FOSS projects. Worked with all .NET 10 previews and RC1 .. fails hard with RC2. Only difference is OS - I am running on Ubuntu.

[michaelnebel]

I managed to reproduce this locally.
It looks like there is a significant difference in, how the compiler calls itself internally between the RC1/Previous dotnet versions and RC2. Typically, the dotnet compiler invokes itself (when doing a dotnet build) by dotnet exec csc.dll .... However, in RC2 it appears that csc is invoked directly, which is not handled correctly in the tracer. Fixing this will require some changes to the tracer and the extractor.

[michaelnebel]

Trying to make a fix here: github/codeql#20663