Merge pull request #3716 from dotty-staging/fix-#3637

Fix #3637: Handle SkolemTypes in avoid

Author: odersky

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

@@ -110,6 +110,8 @@ trait TypeAssigner {
           }
         case tp: ThisType if toAvoid(tp.cls) =>
           range(tp.bottomType, apply(classBound(tp.cls.classInfo)))
+        case tp: SkolemType if partsToAvoid(mutable.Set.empty, tp.info).nonEmpty =>
+          range(tp.info.bottomType, apply(tp.info))
         case tp: TypeVar if ctx.typerState.constraint.contains(tp) =>
           val lo = ctx.typeComparer.instanceType(tp.origin, fromBelow = variance >= 0)
           val lo1 = apply(lo)

tests/pos/i3637.scala

@@ -0,0 +1,10 @@
+import reflect.ClassTag
+
+object Demo {
+  def the[T](implicit ev: T): ev.type = ev // More precise implicitly, needed to crash
+
+  {
+    case class B(i: Int)
+    the[ClassTag[B]] // Has to be the last statement of the block
+  }
+}