Incremential Compiler C#6 breaks Package Manager

This is so annoying. Regularly on updating the incremential compiler the compile fails because we use C#6 features, which do not compile without the incremential compiler, which breaks the package manager, which breaks the incremential compiler which breaks the project.

The only way to fix this so far has been to go back to the last state and retry. When the incremential compiler updates successfully, c#6 works, therefore the project compiles, so the package manager is loaded and therefore the new incremential compiler works.

 

1) 2018.3 has c# 7.3 and Roslyn as built-in and deprecated the incremental compiler package
2) for <= 2018.2, you can switch to 4.x runtime or use a

mcs.rsp

with

-langversion:6

to enable c# 6 without IC active

 

It seems to work in 0.0.42-preview.29 (and worked before) and breaks in 0.0.42-preview.31.

However, as I just saw that the package is actually deprecated we will try to switch.