Known breaking changes in .NET 6+

[rolfbjarne]

This issue lists known breaking changes in .NET 6+.

This are breaking changes that are common to both MonoVM and CoreCLR. Differences between MonoVM and CoreCLR should be listed here: #10795.

In this repository

• The current directory at startup is different for Xamarin.Mac (it's the root directory in the app bundle, instead of the Contents/Resources subdirectory), to get the same behavior between all our platforms. Ref: [runtime] Set the current directory to the root directory of the app bundle for all platforms in .NET. #12104.

External to this repository

• 'ProcessStartInfo.EnvironmentVariables ["FOO"] = null' launches with empty environment variable
• Change Environment.OSVersion to return actual OS version
• MulticastDelegate.BeginInvoke throws a PlatformNotSupportedException. See MulticastDelegate, BeginInvoke throws NotSupportedException dotnet/runtime#16312 and https://devblogs.microsoft.com/dotnet/migrating-delegate-begininvoke-calls-for-net-core/.
• Type.IsInterface returns different values between .NET and Mono for reference types
  • Revert if fixed: 1ef83b9 This is by design.
• .NET does not support WeakAttribute.
• using MonoTouch; doesn't compile anymore: just remove this line
• Environment.SpecialFolder.ProgramFiles maps to NSSearchPathDirectory.ApplicationDirectory (as opposed to /Applications in Xamarin.iOS)
• Reflection-only loads are not supported (Assembly.ReflectionOnlyLoad should throw PNSE dotnet/runtime#7273).
• ILLinker does not allow defining new [Preserve] like attributes using Preserve on another custom attribute, e.g. [assembly: Preserve (typeof (ObfuscationAttribute))]

[rolfbjarne]

This has mostly been migrated to: https://github.com/xamarin/xamarin-macios/wiki/Breaking-changes-in-.NET.