Pre-typer syntactic plugins in Scala 3?

[soronpo]

Another related thread:

Blackbox untyped standard plugins before typer in Scala 3

Scala 3 currently limits the possible plugins either to standard plugins that come after the typer stage or research plugins that can be applied anywhere, but enabled only for nightly and snapshot releases. Since macro annotations are unlikely to be supported any time soon, is it possible to enable standard blackbox untyped plugins to run before typer? This will enable migrating code that depends on Scala 2 blackbox macro annotations to Scala 3 via the plugin mechanism and without being limited…