Plug loophole for "no inlines with opaques" rule

Fixes #12814

Author: odersky

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -651,8 +651,7 @@ object SymDenotations {
     def containsOpaques(using Context): Boolean = is(Opaque) && isClass
 
     def seesOpaques(using Context): Boolean =
-      containsOpaques ||
-      is(Module, butNot = Package) && owner.seesOpaques
+      containsOpaques || isClass && !is(Package) && owner.seesOpaques
 
     /** Is this the denotation of a self symbol of some class?
      *  This is the case if one of two conditions holds:

tests/neg/opaque-inline.scala

@@ -0,0 +1,14 @@
+
+object refined:
+  opaque type Positive = Int
+
+  object Positive extends PositiveFactory
+
+  trait PositiveFactory:
+    inline def apply(value: Int): Positive = f(value) // error: implementation restriction
+    def f(x: Positive): Positive = x
+
+@main def run: Unit =
+  import refined.*
+  val x = 9
+  val nine = Positive.apply(x)