Superhost for Windows & Mac

[agocke]

All native runtime libraries should be statically linked into a single file host for Windows & Mac.

• Make clrjit and coreclr friendlier to static linking on multiple platforms. Reducing DllMain responsibilities, so that singlefile would not need it #43423
• Statically link clrjit and coreclr into singlefile host Link clrjit.dll and coreclr.dll into Windows/Mac host #43072
• Link native libraries in a way that is multiplatform friendly. Improving and unifying handling of native Libraries code in embedded/singlefile scenarios #41299
• Statically link native libraries on Windows, OSX and other platforms that we test/support. Statically link native libraries into singlefilehost on OSX and Windows #43699
• Move build of hosts to clr partition. Hosts, in particular statically linked ones should be built in clr partition. #43700
  (not a requirement but will make things simpler going forward, hard to do though before we do the above)
• Signing on MacOS Single-file: Facilitate signing on mac #3671
• Investigate compression of hosts

Partner dependencies:

• Debugging support (WinDbg/lldb)
• Watson support

[ghost]

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[danmoseley]

Making user story so it appears in the tree

[vitek-karas]

I added another work item: validate that the superhost we produce (when used in an application) works will with AVs - that is, doesn't get marked as a virus. Apparently this has already been a problem for at least some users: https://www.reddit.com/r/csharp/comments/k9pnn0/net_5_single_file_trim_self_contained_detected_as/ with out relatively small host.

This is mostly Windows-only work item I think.

[agocke]

Closing with a tracking issue for the remaining Watson work https://github.com/dotnet/runtime/issues/53832