Linking out of debugging support for .NET5

[marek-safar]

For .NET5 it would be better to have MSBuild property which controls the debugging support as a complete feature. This would cover the following behavior inside linker.

• Debug symbols stripping (including embedded PDBs)
• No special marking of members and types used by the debugger
• Hook up of hidden features in libraries which keep additional types for debugging

This property could be set automatically when '$(DebugType)'=='none'.

[marek-safar]

StackFrame tracking at dotnet/runtime#34910

[eerhardt]

Hook up of hidden features in libraries which keep additional types for debugging

There is a similar story with types that are only necessary for COM. See dotnet/runtime#36659. For both COM and debugging, we are "rooting" specific types in the libraries.

For debugging we have:

• https://github.com/dotnet/runtime/blob/b9275463428b6eebb16531aa20e36cfd9d20797f/src/libraries/System.Linq/src/ILLinkTrim.xml#L3-L6
• A bunch in https://github.com/dotnet/runtime/blob/master/src/coreclr/src/System.Private.CoreLib/ILLinkTrim.xml

We could use the same mechanism to preserve and trim these types based on a "feature switch" that is respected in the descriptor XML files.

[marek-safar]

@eerhardt could you please look into annotating the debugger dependencies in libraries with correct feature tag. I also think as part of this job we need to figure out how to move SPC XML descriptor to src/libraries

[eerhardt]

I believe this issue was addressed for .NET 5. Can it be closed? (I don't have permission to close it)

[marek-safar]

There is still unconditional code in libraries for debugger support but I agree it can be closed for linker

[eerhardt]

There is still unconditional code in libraries for debugger support

Do you happen to have an example? I was under the assumption we got all of them.

[marek-safar]

Nothing major, mostly stuff like stubbing out the whole System.Diagnostics.Debugger type or conditions like https://github.com/dotnet/runtime/blob/6072e4d3a7a2a1493f514cdf4be75a3d56580e84/src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/TaskFactory.cs#L1591