Fix compiling quote in file with no splices

Author: nicolasstucki

compiler/src/dotty/tools/dotc/CompilationUnit.scala

@@ -6,6 +6,7 @@ import util.SourceFile
 import ast.{tpd, untpd}
 import dotty.tools.dotc.ast.tpd.{ Tree, TreeTraverser }
 import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.core.StdNames._
 import dotty.tools.dotc.core.SymDenotations.ClassDenotation
 import dotty.tools.dotc.core.Symbols._
 
@@ -35,13 +36,21 @@ object CompilationUnit {
     assert(!unpickled.isEmpty, unpickled)
     val unit1 = new CompilationUnit(new SourceFile(clsd.symbol.associatedFile, Seq()))
     unit1.tpdTree = unpickled
-    if (forceTrees)
+    if (forceTrees) {
+      val force = new Force
       force.traverse(unit1.tpdTree)
+      unit1.containsQuotesOrSplices = force.containsQuotes
+    }
     unit1
   }
 
   /** Force the tree to be loaded */
-  private object force extends TreeTraverser {
-    def traverse(tree: Tree)(implicit ctx: Context): Unit = traverseChildren(tree)
+  private class Force extends TreeTraverser {
+    var containsQuotes = false
+    def traverse(tree: Tree)(implicit ctx: Context): Unit = {
+      if (tree.symbol.name.eq(nme.QUOTE) && tree.symbol.owner.eq(defn.OpsPackageClass))
+        containsQuotes = true
+      traverseChildren(tree)
+    }
   }
 }

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

@@ -203,7 +203,9 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
               // might be a type constructor.
               Checking.checkInstantiable(tree.tpe, nu.pos)
               withNoCheckNews(nu :: Nil)(super.transform(tree))
-            case _ =>
+            case meth =>
+              if (meth.symbol.name.eq(nme.QUOTE) && meth.symbol.owner.eq(defn.OpsPackageClass))
+                ctx.compilationUnit.containsQuotesOrSplices = true
               super.transform(tree)
           }
         case tree: TypeApply =>

tests/pos/quote-no-splices.scala

@@ -0,0 +1,9 @@
+class Foo {
+  def foo: Unit = {
+    val expr ='{
+      val a = 3
+      println("foo")
+      2 + a
+    }
+  }
+}