[.NET 6] External linker issues

[rolfbjarne]

This issue lists all issues from the mono/linker repository that affect our .NET 6 effort.

Issues in any dotnet/* repository are listed in #8901.

The checkbox should be checked once the external issue is fixed, and the issue
moved down to "Fixed in ". When we've removed any workarounds or
implemented other related behavior to the issue in question the issue should
be moved down to "Fixed in our repo".

Equivalent issue for .NET 7: #14549.

Known breaking changes in .NET 6+ should be listed here: #8900.
Known breaking changes in CoreCLR should be listed here: #10795.

P0: something that's blocking other work for us
P1: something we can't go to stable with
P2: neither P0 nor P1

P0

P1

P2

### Moved to .NET 7 (#14549)

• Setting NullabilityInfoContextSupport=false prevents ILLink.Substitutions.xml from being removed from System.Runtime.InteropServices.dll
  • Nothing to do on our side (except bump) once this is fixed.

Fixed in mono/linker

Fixed in our repo

• Custom steps can't use error codes outside [1000, 2000]
  • [dotnet-linker] Improve the error message from the linker when we run into a problem. #14253
• The Mono.Cecil version in the Microsoft.NET.ILLink NuGet is wrong
• iOS: AssemblyDefinition.MainModule.FileName is not set
  • Will be fixed with Bump to .NET 6.0.100-preview.3.21161.23 #10772.
• error IL1001: Failed to process 'resource System.Private.CoreLib.xml in System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'. Feature 'sre' does not specify a 'featurevalue' attribute
• XmlSerializer.Serialize doesn't work when using TrimMode=link
  • Revert once fixed: 9cbf145 (#9509)
  • Reverted: 710604a
• AnnotationStore.SetMethodStubValue should be in the reference assembly
  • Revert: [dotnet] Bump ILLink to get an updated linker reference assembly. #10450
• The same assembly is loaded multiple times if it passed as multiple --custom-step arguments
• ~Unable to resolve some types from System.Runtime.dll in custom linker step ~
• Trimming BlazorWeather app is slow
• The 'seal' optimization fails with XmlSerializer (not a bug in the linker)
• SweepStep doesn't process all type references for forwarded types
  • Blocking [dotnet] Remove workaround for mono/linker#1304, which has now been fixed. #9862
• NRE in SubStepsDispatcher
  • Reverted with Revert "[dotnet-linker] Make PreserveSmartEnumConversionsStep active for type as well to work around a linker bug." #11064
• Linker doesn't consider assembly references from custom attributes
  • Reverted: aa67191
• AnnotationStore.AddPreservedMethod (MethodDefinition key, MethodDefinition method) should be in the reference assembly
  • Workaround removed: fc5ae53
• Crash after linking code using DataContractSerializer
  • reverted with Revert "[tests] Ignore linkall's DataContractTest in .NET due to a linker bug." #11042 bf8bcda
• Processed debug symbols aren't copied to the publish directory
• Type converters are linked away in .NET 5+ when using TrimMode=link
• LinkContext.GetAssemblies should be exposed in the reference assembly
  • By design
• Linker does not remove unused method when the method implements interface
  • By design
• IL1012: Unhandled exception. System.ArgumentOutOfRangeException: Length cannot be less than zero
  • Revert once fixed: [dotnet] Don't include the F# library in monotouch-test yet, it makes the linker crash. #9462
  • Revert: [dotnet] Remove workaround for mono/linker#1435, which has now been fixed. #9863