After some testing, it looks like the TextTemplating library that is part of VisualStudio (Microsoft.VisualStudio.TextTemplating.15.0.dll) can't be used in the newer "dotnet" command line toolchain as it depends on the WPF assembly WindowsBase.dll. This causes the .tt code generation to fail, even on a Windows machine.
After some investigation, we found some open-source projects that are able to do .tt code generation, most notably mono/t4, but these solutions have the disadvantage of not being so well integrated with VisualStudio as the current TextTemplating is. For example, it's harder (if not impossible) to get design-time generation and we also lose the ability to trigger the code generation from the context menu in the solution explorer.
Given these drawbacks, I'd just like to know what is Microsoft's position on this. Is there a plan to update the existing TextTemplating libraries so that they are compatible with the "dotnet" toolchain while still maintaining good integration within the VS IDE? Or is TextTemplating being left behind and we must rely on the not-so-well-integrated open-source solutions?