Add libraries that require replacement for Evals.eval

[plokhotnyuk]

Libraries have a couple of use cases where Evals.eval was used in compile-time:

1. for expensive calculations of LUT tables that should happen in compile-time and produce resulting array of primitives (one possible solution provided below in comments, but it leads to code duplication between Scala 2 and Scala 3 codebases) The proposed solution for Scala 3 is here.
2. for injecting user-defined pure functions that configure behavior during macro expansions, so should be instantiated and called in compile-time (sort of a principal problem due Scala 2 macros cannot use parameters that are not expressions)
3. as workaround for getting of Java enumeration values in compile time for Scala 2.11 (can be easily moved to Scala 2 only codebase) Fixed by using Magnolia's code for getting of companions.
4. as workaround for getting of parameter values of macro annotations for cases when it cannot be done by simple pattern matching (Scala 2 compiler allows expression in definitions of macro annotations but doesn't reduce them to constants automaticaly)

Any feedback will be greatly appreciated!

[plokhotnyuk]

Also, specs2 uses Evals.eval in its type check implementation

[nicolasstucki]

The first one can be ported using scala/scala3#8878

[julienrf]

The first one can be ported using lampepfl/dotty#8878

Would you have some time to include an explanation of the migration in this guide?

[adpi2]

@nicolasstucki @plokhotnyuk
Is this "No replacement for Evals.eval" still relevant? Is there a discussion somewhere on that topic?

[nicolasstucki]

It is probably relevant. Not sure if there is a discussion somewhere.