Add some post conditions to ReifyQuotes

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/ReifyQuotes.scala

@@ -74,6 +74,21 @@ class ReifyQuotes extends MacroTransformWithImplicits {
 
   override def phaseName: String = "reifyQuotes"
 
+  override def checkPostCondition(tree: tpd.Tree)(implicit ctx: Context): Unit = {
+    if (ctx.owner.ownersIterator.exists(_.isTransparentMethod)) {
+      tree match {
+        case tree: Select if tree.symbol == defn.QuotedExpr_~ =>
+          assert(Splicer.canBeSpliced(tree.qualifier))
+        case _ =>
+      }
+    } else {
+      assert(tree.symbol != defn.QuotedExpr_~)
+      // assert(tree.symbol != defn.QuotedType_~) // TODO widen ~ type references at stage 0?
+      assert(tree.symbol != defn.QuotedExpr_apply)
+      assert(tree.symbol != defn.QuotedType_apply)
+    }
+  }
+
   override def run(implicit ctx: Context): Unit =
     if (ctx.compilationUnit.containsQuotesOrSplices) super.run