Unable to build on iOS due to missing reference to 'System.Private.Corelib'

[EricLVertiGIS]

Apple platform

iOS

Framework version

net9.0-*

Affected platform version

NET 9.0.304

Description

Hi, we created a .NuGet package using the NuGetCommand@2 on Azure. The .NuGet package contains .NET Maui views and libraries. We then have a .NET Maui project that consumes that .NuGet package to display the views. This works fine in .NET 8.

After updating to .NET 9, the original project (that the .NuGet package is built from) runs fine on iOS. But the project consuming the package gets the following errors when building on iOS:

The type 'EventHandler' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.

The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.

The type 'TimeSpan' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.

Builds fine when targeting Android or Windows, hence I am raising this question in the Xamarin.iOS project. Both projects are on .NET Maui 9.0.90 and .NET version 9.0.304 (9.0.8 runtime). I have tried :

• Clearing nuget cache
• Restarting Visual Studio
• Reinstalling Maui & .NET
• Disable trimming on iOS
• Add SkipStaticValidation = true on my .csproj
• Made sure both projects target 'net9.0-ios'.

None of these options worked. It seems weird to me that Windows & Android could run when missing System.Private.Corelib. Could someone help me find the cause of this issue ?

Steps to Reproduce

1. Create .NET Maui project which includes a view / viewmodel that is declared public.
2. Package the project into a .NuGet package via DotNet Publish and NuGetCommand@2

          - task: NuGetToolInstaller@1
            displayName: 'Use NuGet 6.x'
            inputs:
              versionSpec: 6.x
             
          - task: DotNetCoreCLI@2
            displayName: 'Build for net9.0 target'
            inputs:
              command: 'build'
              publishWebProjects: false
              projects: 'Mobile/VertiGIS.Mobile.csproj'
              arguments: '-f net9.0 -c Release /nowarn:NU1903;NU1904;XC0025;XC0103 -p:RunAnalyzers=false'
              zipAfterPublish: false
              modifyOutputPath: false
            
          - task: NuGetCommand@2
            displayName: "Create Mobile NuGet Package"
            inputs:
              command: "pack"
              packagesToPack: "_NuGet/VertiGIS.Mobile.nuspec"
              configuration: "release"
              packDestination: "$(ArtifactDirectory)/Packages"
              versioningScheme: "byEnvVar"
              versionEnvVar: "Build.NugetVersion"

3. Add the nuget package as a dependency to a .NET Maui project. Consume the public views from the nuget package.
4. Try to build on iOS.

Did you find any workaround?

No response

Build logs

1>Including assemblies for Hot Reload support
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(12,24,12,34): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(19,13,19,21): warning CS0618: 'Application.MainPage.set' is obsolete: 'This property is deprecated. Initialize your application by overriding Application.CreateWindow rather than setting MainPage. To modify the root page in an active application, use Windows[0].Page for applications with a single window. For applications with multiple windows, use Application.Windows to identify and update the root page on the correct window.  Additionally, each element features a Window property, accessible when it's part of the current window.'
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(62,32,62,45): error CS0012: The type 'EventHandler<>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(66,24,66,37): error CS0012: The type 'EventHandler<>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(73,39,73,54): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(73,19,73,54): error CS0012: The type 'Task' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(75,66,75,78): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(75,33,75,78): error CS0012: The type 'Task<>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(76,52,76,67): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(76,19,76,67): error CS0012: The type 'Task' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(82,33,82,47): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\App.xaml.cs(94,37,94,48): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(43,20,43,24): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(43,42,43,71): error CS0012: The type 'TimeSpan' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(43,13,43,24): error CS0012: The type 'FormattableString' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(47,33,47,41): error CS0012: The type 'EventHandler' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(49,17,49,53): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(51,28,51,54): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(56,13,56,29): error CS0012: The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.
1>C:\Users\eliu\source\repos\vertigis-mobile-quickstart\App1\Platforms\iOS\AppDelegate.cs(58,33,58,41): error CS0012: The type 'EventHandler' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'.

[EricLVertiGIS]

Compared to Windows and Android, the folder /lib/net9.0-ios18.0 inside the nuget package contains a file called System.Private.Corelib.aotdata.arm64 that isn't present in the other platforms. Could this file cause any conflicts ?

[EricLVertiGIS]

It seems that calling static functions from the original project (that the nuget package is built from) in the consuming project is more likely to trigger these exceptions.

[rolfbjarne]

folder /lib/net9.0-ios18.0 inside the nuget package contains a file called System.Private.Corelib.aotdata.arm64

That's very strange, it shouldn't be there.

Are you trying to create a NuGet from an executable project?

In any case could you get an MSBuild binlog for the build that creates the NuGet + the build with the build error? This will hopefully give us some hints as to where things go wrong.

[EricLVertiGIS]

Hi @rolfbjarne, the DLLs for our NuGet package are built in our pipeline. To simulate, I built the project locally in the iOS release configuration and captured the binlogs as requested:

Logs.zip

I think the main issue here is in some of our classes, it tries to resolve System.Private.Corelib instead of System.Runtime. I'm not sure what causes this behavior. If I run 'Pack' in Visual Studio (instead building in release + NuGet pack in the pipeline), then the same class will use System.Runtime correctly. The image is from decompiling the NuGet package classes in Visual Studio:

Further Questions:

• We are using nuget pack, could dotnet pack make a difference ?
• We are using aliases & extern to use the System.Interactive.Asyc package, could that create 'confusion' when resolving dependancies ?
• Our working .Net 8 package has System.Private.Corelib.aotdata.arm64 as well as aot-instances.aotdata.arm64 in the \lib\net8.0-17.2 folder. The latter file is missing in our .Net 9 package.

[rolfbjarne]

• We are using nuget pack, could dotnet pack make a difference ?

Yes, this might be the problem, please try dotnet pack instead.

• We are using aliases & extern to use the System.Interactive.Asyc package, could that create 'confusion' when resolving dependancies ?

I don't think this is the case, because alias/extern is something limited to the C# compiler, and it's not visible in the compiled result if alias/extern was used during compilation.

• Our working .Net 8 package has System.Private.Corelib.aotdata.arm64 as well as aot-instances.aotdata.arm64 in the \lib\net8.0-17.2 folder. The latter file is missing in our .Net 9 package.

This file should not be in the nupkg, because the nupkg doesn't contain aot-compiled code (aot-compilation happens when the final app, where the NuGet is used, is built).

To simulate, I built the project locally in the iOS release configuration and captured the binlogs as requested:

This didn't quite work, because VS wasn't connected to the Mac for this build.

Can you add -bl:msbuild.binlog do the dotnet pack command in the pipeline, get that binlog and upload that instead?