Fix #6992: Add back heuristic to detect scope extrusion

This heristic can detects and fails-fast when an Expr or Type is used with a different compiler instance.

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala

@@ -14,6 +14,7 @@ import dotty.tools.dotc.core.Types._
 import dotty.tools.dotc.core.tasty.TreePickler.Hole
 import dotty.tools.dotc.core.tasty.{PositionPickler, TastyPickler, TastyPrinter, TastyString}
 import dotty.tools.dotc.core.tasty.TreeUnpickler.UnpickleMode
+import dotty.tools.dotc.quoted.ToolboxImpl
 import dotty.tools.dotc.tastyreflect.ReflectionImpl
 
 import scala.internal.quoted._
@@ -35,12 +36,18 @@ object PickledQuotes {
   }
 
   /** Transform the expression into its fully spliced Tree */
-  def quotedExprToTree[T](expr: quoted.Expr[T])(implicit ctx: Context): Tree =
-    healOwner(expr.asInstanceOf[TastyTreeExpr[Tree]].tree)
+  def quotedExprToTree[T](expr: quoted.Expr[T])(implicit ctx: Context): Tree = {
+    val expr1 = expr.asInstanceOf[TastyTreeExpr[Tree]]
+    ToolboxImpl.checkScopeId(expr1.scopeId)
+    healOwner(expr1.tree)
+  }
 
   /** Transform the expression into its fully spliced TypeTree */
-  def quotedTypeToTree(expr: quoted.Type[_])(implicit ctx: Context): Tree =
-    healOwner(expr.asInstanceOf[TreeType[Tree]].typeTree)
+  def quotedTypeToTree(tpe: quoted.Type[_])(implicit ctx: Context): Tree = {
+    val tpe1 = tpe.asInstanceOf[TreeType[Tree]]
+    ToolboxImpl.checkScopeId(tpe1.scopeId)
+    healOwner(tpe1.typeTree)
+  }
 
   private def dealiasTypeTags(tp: Type)(implicit ctx: Context): Type = new TypeMap() {
     override def apply(tp: Type): Type = {

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -31,6 +31,7 @@ import scala.collection.mutable.ListBuffer
 import scala.collection.mutable
 import config.Printers.pickling
 import core.quoted.PickledQuotes
+import dotty.tools.dotc.quoted.ToolboxImpl
 
 import scala.quoted
 import scala.internal.quoted.{TastyTreeExpr, TreeType}
@@ -1273,8 +1274,8 @@ class TreeUnpickler(reader: TastyReader,
       val args = until(end)(readTerm())
       val splice = splices(idx)
       def wrap(arg: Tree) =
-        if (arg.isTerm) given (qctx: scala.quoted.QuoteContext) => new TastyTreeExpr(arg)
-        else new TreeType(arg)
+        if (arg.isTerm) given (qctx: scala.quoted.QuoteContext) => new TastyTreeExpr(arg, ToolboxImpl.scopeId)
+        else new TreeType(arg, ToolboxImpl.scopeId)
       val reifiedArgs = args.map(wrap)
       val filled = if (isType) {
         val quotedType = splice.asInstanceOf[Seq[Any] => quoted.Type[_]](reifiedArgs)

compiler/src/dotty/tools/dotc/quoted/ToolboxImpl.scala

@@ -1,5 +1,7 @@
 package dotty.tools.dotc.quoted
 
+import dotty.tools.dotc.core.Contexts.Context
+
 import scala.quoted._
 
 /** Default runners for quoted expressions */
@@ -20,14 +22,25 @@ object ToolboxImpl {
     def run[T](exprBuilder: QuoteContext => Expr[T]): T = synchronized {
       try {
         if (running) // detected nested run
-          throw new scala.quoted.Toolbox.ToolboxAlreadyRunning()
+          throw new scala.quoted.Toolbox.RunScopeException()
         running = true
         driver.run(exprBuilder, settings)
       } finally {
         running = false
       }
     }
+  }
 
+  type ScopeId = Int
+
+  private[dotty] def checkScopeId(id: ScopeId) given Context: Unit = {
+    if (id != scopeId)
+      throw new Toolbox.RunScopeException
   }
 
+  // TODO Explore more fine grained scope ids.
+  //      This id can only differentiate scope extrusion from one compiler instance to another.
+  private[dotty] def scopeId given Context: ScopeId =
+    the[Context].outersIterator.toList.last.hashCode()
+
 }

compiler/src/dotty/tools/dotc/tastyreflect/ReflectionCompilerInterface.scala

@@ -34,10 +34,10 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   //
 
   def unpickleExpr(repr: Unpickler.PickledQuote, args: Unpickler.PickledExprArgs): scala.quoted.Expr[_] =
-    new scala.internal.quoted.TastyTreeExpr(PickledQuotes.unpickleExpr(repr, args))
+    new scala.internal.quoted.TastyTreeExpr(PickledQuotes.unpickleExpr(repr, args), compilerId)
 
   def unpickleType(repr: Unpickler.PickledQuote, args: Unpickler.PickledTypeArgs): scala.quoted.Type[_] =
-    new scala.internal.quoted.TreeType(PickledQuotes.unpickleType(repr, args))
+    new scala.internal.quoted.TreeType(PickledQuotes.unpickleType(repr, args), compilerId)
 
   //
   // CONTEXT
@@ -1752,7 +1752,7 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
         tpd.Closure(closureMethod, tss => etaExpand(new tpd.TreeOps(term).appliedToArgs(tss.head)))
       case _ => term
     }
-    new scala.internal.quoted.TastyTreeExpr(etaExpand(self))
+    new scala.internal.quoted.TastyTreeExpr(etaExpand(self), compilerId)
   }
 
   /** Checked cast to a `quoted.Expr[U]` */
@@ -1773,7 +1773,7 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   /** Convert `Type` to an `quoted.Type[_]` */
   def QuotedType_seal(self: Type) given (ctx: Context): scala.quoted.Type[_] = {
     val dummySpan = ctx.owner.span // FIXME
-    new scala.internal.quoted.TreeType(tpd.TypeTree(self).withSpan(dummySpan))
+    new scala.internal.quoted.TreeType(tpd.TypeTree(self).withSpan(dummySpan), compilerId)
   }
 
   //
@@ -1934,4 +1934,6 @@ class ReflectionCompilerInterface(val rootContext: core.Contexts.Context) extend
   private def withDefaultPos[T <: Tree](fn: given Context => T) given (ctx: Context): T =
     (fn given ctx.withSource(rootPosition.source)).withSpan(rootPosition.span)
 
+  private def compilerId: Int = rootContext.outersIterator.toList.last.hashCode()
+
 }

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

@@ -25,7 +25,7 @@ import dotty.tools.repl.AbstractFileClassLoader
 
 import scala.reflect.ClassTag
 
-import dotty.tools.dotc.quoted.QuoteContext
+import dotty.tools.dotc.quoted.{QuoteContext, ToolboxImpl}
 
 /** Utility class to splice quoted expressions */
 object Splicer {
@@ -251,10 +251,10 @@ object Splicer {
     }
 
     private def interpretQuote(tree: Tree)(implicit env: Env): Object =
-      new scala.internal.quoted.TastyTreeExpr(Inlined(EmptyTree, Nil, tree).withSpan(tree.span))
+      new scala.internal.quoted.TastyTreeExpr(Inlined(EmptyTree, Nil, tree).withSpan(tree.span), ToolboxImpl.scopeId)
 
     private def interpretTypeQuote(tree: Tree)(implicit env: Env): Object =
-      new scala.internal.quoted.TreeType(tree)
+      new scala.internal.quoted.TreeType(tree, ToolboxImpl.scopeId)
 
     private def interpretLiteral(value: Any)(implicit env: Env): Object =
       value.asInstanceOf[Object]

library/src/scala/quoted/Expr.scala

@@ -79,7 +79,7 @@ package quoted {
 package internal {
   package quoted {
 
-    import scala.quoted.{Expr, QuoteContext}
+    import scala.quoted.Expr
 
     /** An Expr backed by a tree. Only the current compiler trees are allowed.
      *
@@ -88,7 +88,7 @@ package internal {
      *
      *  May contain references to code defined outside this TastyTreeExpr instance.
      */
-    final class TastyTreeExpr[Tree](val tree: Tree) extends Expr[Any] {
+    final class TastyTreeExpr[Tree](val tree: Tree, val scopeId: Int) extends Expr[Any] {
       override def toString: String = s"Expr(<tasty tree>)"
     }
 

library/src/scala/quoted/Toolbox.scala

@@ -57,6 +57,6 @@ object Toolbox {
 
   class ToolboxNotFoundException(msg: String, cause: ClassNotFoundException) extends Exception(msg, cause)
 
-  class ToolboxAlreadyRunning extends Exception("Cannot call `scala.quoted.run(...)` within another `run(...)`")
+  class RunScopeException extends Exception("Cannot call `scala.quoted.run(...)` within a macro or another `run(...)`")
 
 }

library/src/scala/quoted/Type.scala

@@ -70,7 +70,7 @@ package internal {
   package quoted {
 
     /** An Type backed by a tree */
-    final class TreeType[Tree](val typeTree: Tree) extends scala.quoted.Type[Any] {
+    final class TreeType[Tree](val typeTree: Tree, val scopeId: Int) extends scala.quoted.Type[Any] {
       override def toString: String = s"Type(<tasty tree>)"
     }
 

tests/run-macros/i6992/Macro_1.scala

@@ -0,0 +1,23 @@
+
+import scala.quoted._, scala.quoted.matching._
+import delegate scala.quoted._
+
+delegate for Toolbox = Toolbox.make(getClass.getClassLoader)
+
+object macros {
+  inline def mcr(x: => Any): Any = ${mcrImpl('x)}
+
+  class Foo { val x = 10 }
+
+  def mcrImpl(body: Expr[Any]) given (ctx: QuoteContext): Expr[Any] = {
+    import ctx.tasty._
+    try {
+      body match {
+        case '{$x: Foo} => run(x).x.toExpr
+      }
+    } catch {
+      case _: scala.quoted.Toolbox.RunScopeException =>
+        '{"OK"}
+    }
+  }
+}

tests/run-macros/i6992/Test_2.scala

@@ -0,0 +1,9 @@
+import macros._
+
+object Test {
+  val foo = new Foo
+
+  def main(args: Array[String]) = {
+    println(mcr {foo})
+  }
+}