Merge pull request #254 from scala/backport-lts-3.3-22618

Backport "Fix issue with static `this` references erroring in quoted code" to 3.3 LTS

Author: tgodzik

compiler/src/dotty/tools/dotc/staging/CrossStageSafety.scala

@@ -189,19 +189,27 @@ class CrossStageSafety extends TreeMapWithStages {
 
   /** Check level consistency of terms references */
   private def checkLevelConsistency(tree: Ident | This)(using Context): Unit =
+    def isStatic(pre: Type)(using Context): Boolean = pre match
+      case pre: NamedType =>
+        val sym = pre.currentSymbol
+        sym.is(Package) || sym.isStaticOwner && isStatic(pre.prefix)
+      case pre: ThisType => isStatic(pre.tref)
+      case _ => true
     new TypeTraverser {
       def traverse(tp: Type): Unit =
         tp match
           case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level != levelOf(tp.symbol) =>
             levelError(tp.symbol, tp, tree.srcPos)
+          case tp: ThisType if isStatic(tp) =>
+            // static object (OK)
           case tp: ThisType if level != -1 && level != levelOf(tp.cls) =>
             levelError(tp.cls, tp, tree.srcPos)
           case tp: AnnotatedType =>
             traverse(tp.parent)
           case _ if tp.typeSymbol.is(Package) =>
             // OK
           case _ =>
-             traverseChildren(tp)
+            traverseChildren(tp)
     }.traverse(tree.tpe)
 
   private def levelError(sym: Symbol, tp: Type, pos: SrcPos)(using Context): tp.type = {

tests/neg/i22592.scala

@@ -0,0 +1,14 @@
+import scala.quoted.*
+
+trait Foo:
+  def inherited = ()
+
+class Bar extends Foo:
+  def local = ()
+  def localArg(arg: Any) = ()
+
+  def macro1(using Quotes): Expr[Unit] = '{ local } // error
+  def macro3(using Quotes): Expr[Unit] = '{ inherited } // error
+  def macro4(using Quotes): Expr[Unit] = '{ this.local } // error
+  def macro5(using Quotes): Expr[Unit] = '{ this.inherited } // error
+  def macro6(using Quotes): Expr[Unit] = '{ localArg(this) } // error // error

tests/pos/i22592.scala

@@ -0,0 +1,15 @@
+import scala.quoted.*
+
+trait Foo:
+  def inherited = ()
+
+object Bar extends Foo:
+  def local = ()
+  def localArg(arg: Any) = ()
+
+  def macro1(using Quotes): Expr[Unit] = '{ local }
+  def macro2(using Quotes): Expr[Unit] = '{ Bar.inherited }
+  def macro3(using Quotes): Expr[Unit] = '{ inherited }
+  def macro4(using Quotes): Expr[Unit] = '{ this.local }
+  def macro5(using Quotes): Expr[Unit] = '{ this.inherited }
+  def macro6(using Quotes): Expr[Unit] = '{ localArg(this) }