Delay roll-out of new prioritization scheme:

Now:

  3.5: old scheme but warn if there are changes in the future
  3.6-migration: new scheme, warn if prioritization has changed
  3.6: new scheme, no warning

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1838,7 +1838,7 @@ trait Applications extends Compatibility {
         val tp1p = prepare(tp1)
         val tp2p = prepare(tp2)
 
-        if Feature.sourceVersion.isAtMost(SourceVersion.`3.4`)
+        if Feature.sourceVersion.isAtMost(SourceVersion.`3.5`)
             || oldResolution
             || !alt1isGiven && !alt2isGiven
         then