Perform typer realizability checks only during Typer.

Author: odersky

src/dotty/tools/dotc/typer/Typer.scala

@@ -986,7 +986,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     val impl1 = cpy.Template(impl)(constr1, parents1, self1, body1)
       .withType(dummy.nonMemberTermRef)
     checkVariance(impl1)
-    if (!cls.is(AbstractOrTrait)) checkRealizableBounds(cls.typeRef, cdef.pos)
+    if (!cls.is(AbstractOrTrait) && !ctx.isAfterTyper) checkRealizableBounds(cls.typeRef, cdef.pos)
     assignType(cpy.TypeDef(cdef)(name, impl1, Nil), cls)
 
     // todo later: check that
@@ -1058,7 +1058,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   def typedImport(imp: untpd.Import, sym: Symbol)(implicit ctx: Context): Import = track("typedImport") {
     val expr1 = typedExpr(imp.expr, AnySelectionProto)
     checkStable(expr1.tpe, imp.expr.pos)
-    checkRealizable(expr1.tpe, imp.expr.pos)
+    if (!ctx.isAfterTyper) checkRealizable(expr1.tpe, imp.expr.pos)
     assignType(cpy.Import(imp)(expr1, imp.selectors), sym)
   }