"Clean" target does not delete all files in bin/obj folders

[marcoburato-ecutek]

Apple platform

iOS

Framework version

net8.0-*

Affected platform version

.NET 8.0.404, iOS workload 18.0.8319/8.0.100, JetBrains Rider 2024.3.3

Description

After upgrading to the latest .NET SDK, iOS workload and Xcode, our iOS app would build but crash on startup with an odd error:

System.DllNotFoundException: __Internal

I tried rebuilding the project but go the same behaviour.
I then switched to our Android app (within the same solution) just to test my code changes.

Today I switched back to the iOS project and it would no longer even build:

error : clang++ exited with code 1:
error : Undefined symbols for architecture x86_64:
error :   "_xamarin_is_object_valid", referenced from:
error :       <initial-undefines>
error :   "_xamarin_is_user_type", referenced from:
error :       <initial-undefines>
error : ld: symbol(s) not found for architecture x86_64
error : clang++: error: linker command failed with exit code 1 (use -v to see invocation)

At this point, I manually deleted the bin and obj folders, built the project again and it all worked correctly, like it used to.
It looks like the MSBuild Clean target does not delete all files within those output folders and some old files are not compatible with the new build tools.

Specifically, when I clean the project from my IDE, JetBrains Rider, there are about 137MB of files left under obj/Debug/net8.0-ios/iossimulator-x64.
Interestingly, cleaning the project from the command line with dotnet clean does work as intended, all files in obj/Debug/net8.0-ios get deleted.

Looking at the MSBuild outputs, it looks like CoreClean is not deleting any file when invoked from the IDE.
Since I experienced the same symptoms with Visual Studio for Mac, I suspect there's an issue with the MSBuild script and this not a bug in Rider. From what I can see, it's just invoking the Clean target as it should.

Steps to Reproduce

1. Build the project from the IDE
2. Clean the project from the IDE
3. Check bin/obj folders, observe there are still many files left

Did you find any workaround?

Manually deleting the bin/obj folders fixes the build.

Build logs

No response

[rolfbjarne]

Thanks for the report, we'll have a look and see what we can figure out.