Revert "Remove support -scala-output-version with quotes"

This reverts commit ca01392.

Fixes #14989

Author: nicolasstucki

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

@@ -827,7 +827,9 @@ class Definitions {
 
 
   @tu lazy val QuoteUnpicklerClass: ClassSymbol = requiredClass("scala.quoted.runtime.QuoteUnpickler")
+    @tu lazy val QuoteUnpickler_unpickleExpr: Symbol = QuoteUnpicklerClass.requiredMethod("unpickleExpr")
     @tu lazy val QuoteUnpickler_unpickleExprV2: Symbol = QuoteUnpicklerClass.requiredMethod("unpickleExprV2")
+    @tu lazy val QuoteUnpickler_unpickleType: Symbol = QuoteUnpicklerClass.requiredMethod("unpickleType")
     @tu lazy val QuoteUnpickler_unpickleTypeV2: Symbol = QuoteUnpicklerClass.requiredMethod("unpickleTypeV2")
 
   @tu lazy val QuoteMatchingClass: ClassSymbol = requiredClass("scala.quoted.runtime.QuoteMatching")

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

@@ -50,7 +50,7 @@ object PickledQuotes {
   /** `typeHole`/`types` argument of `QuoteUnpickler.{unpickleExpr,unpickleExprV2,unpickleType,unpickleTypeV2}` */
   enum TypeHole:
     /** `termHole` argument of `QuoteUnpickler.{unpickleExpr, unpickleType}`.
-     *  From code compiled with Scala 3.0.x and 3.1.x.
+     *  From code compiled with Scala 3.0.x and 3.1.x or with -scala-output-version 3.0 and 3.1
      *  Note: For `unpickleType` it will always be `null`.
      */
     case V1(evalHole: Null | ((Int, Seq[scala.quoted.Type[?]]) => scala.quoted.Type[?]))
@@ -65,7 +65,7 @@ object PickledQuotes {
 
   enum ExprHole:
     /** `termHole` argument of `QuoteUnpickler.{unpickleExpr, unpickleType}`.
-     *  From code compiled with Scala 3.0.x and 3.1.x.
+     *  From code compiled with Scala 3.0.x and 3.1.x or with -scala-output-version 3.0 and 3.1
      *  Note: For `unpickleType` it will always be `null`.
      */
     case V1(evalHole: Null | ((Int, Seq[ExprHole.ArgV1], scala.quoted.Quotes) => scala.quoted.Expr[?]))

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

@@ -291,6 +291,9 @@ object PickleQuotes {
       *  this closure is always applied directly to the actual context and the BetaReduce phase removes it.
       */
     def pickleAsTasty() = {
+
+      val unpickleV1 = ctx.scalaRelease <= Release3_1
+
       val pickleQuote = PickledQuotes.pickleQuote(body)
       val pickledQuoteStrings = pickleQuote match
         case x :: Nil => Literal(Constant(x))
@@ -303,8 +306,26 @@ object PickleQuotes {
 
       // This and all closures in typeSplices are removed by the BetaReduce phase
       val types =
-        if typeSplices.isEmpty then Literal(Constant(null)) // keep pickled quote without contents as small as possible
-        else SeqLiteral(typeSplices.map(_._1), TypeTree(defn.QuotedTypeClass.typeRef.appliedTo(WildcardType)))
+        if unpickleV1 then
+          if typeSplices.isEmpty then Literal(Constant(null)) // keep pickled quote without contents as small as possible
+          else
+            Lambda(
+              MethodType(
+                List(nme.idx, nme.contents).map(name => UniqueName.fresh(name).toTermName),
+                List(defn.IntType, defn.SeqType.appliedTo(defn.AnyType)),
+                defn.QuotedTypeClass.typeRef.appliedTo(WildcardType)),
+              args => {
+                val cases = typeSplices.map { case (splice, idx) =>
+                  CaseDef(Literal(Constant(idx)), EmptyTree, splice)
+                }
+                cases match
+                  case CaseDef(_, _, rhs) :: Nil => rhs
+                  case _ => Match(args(0).annotated(New(ref(defn.UncheckedAnnot.typeRef))), cases)
+              }
+            )
+          else // if unpickleV2 then
+            if typeSplices.isEmpty then Literal(Constant(null)) // keep pickled quote without contents as small as possible
+            else SeqLiteral(typeSplices.map(_._1), TypeTree(defn.QuotedTypeClass.typeRef.appliedTo(WildcardType)))
 
       // This and all closures in termSplices are removed by the BetaReduce phase
       val termHoles =
@@ -320,7 +341,12 @@ object PickleQuotes {
                 val defn.FunctionOf(argTypes, defn.FunctionOf(quotesType :: _, _, _, _), _, _) = splice.tpe
                 val rhs = {
                   val spliceArgs = argTypes.zipWithIndex.map { (argType, i) =>
-                    args(1).select(nme.apply).appliedTo(Literal(Constant(i))).asInstance(argType)
+                    val argi = args(1).select(nme.apply).appliedTo(Literal(Constant(i)))
+                    if unpickleV1 && argType.derivesFrom(defn.QuotedExprClass) then
+                      val argType1 = defn.FunctionType(1).appliedTo(defn.QuotesClass.typeRef, argType)
+                      argi.asInstance(argType1).select(nme.apply).appliedTo(args(2))
+                    else
+                      argi.asInstance(argType)
                   }
                   val Block(List(ddef: DefDef), _) = splice
                   // TODO: beta reduce inner closure? Or wait until BetaReduce phase?
@@ -337,10 +363,14 @@ object PickleQuotes {
       val quotedType = quoteClass.typeRef.appliedTo(originalTp)
       val lambdaTpe = MethodType(defn.QuotesClass.typeRef :: Nil, quotedType)
       val unpickleMeth =
-        if isType then defn.QuoteUnpickler_unpickleTypeV2
-        else defn.QuoteUnpickler_unpickleExprV2
+        if unpickleV1 then
+          if isType then defn.QuoteUnpickler_unpickleType
+          else defn.QuoteUnpickler_unpickleExpr
+        else // if unpickleV2 then
+          if isType then defn.QuoteUnpickler_unpickleTypeV2
+          else defn.QuoteUnpickler_unpickleExprV2
       val unpickleArgs =
-        if isType then List(pickledQuoteStrings, types)
+        if isType && !unpickleV1 then List(pickledQuoteStrings, types)
         else List(pickledQuoteStrings, types, termHoles)
       quotes
         .asInstance(defn.QuoteUnpicklerClass.typeRef)

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

@@ -135,7 +135,13 @@ class Splicing extends MacroTransform:
               val hole = tpd.Hole(false, holeIdx, Nil, ref(qual), TypeTree(tp))
               typeHoles.put(qual.symbol, hole)
               hole
-          cpy.TypeDef(tree)(rhs = hole)
+          val rhs =
+            if ctx.scalaRelease <= Release3_1 then
+              val secondHoleIdx = numHoles
+              numHoles += 1
+              TypeBoundsTree(hole, cpy.Hole(hole)(idx = secondHoleIdx))
+            else hole
+          cpy.TypeDef(tree)(rhs = rhs)
         case Apply(Select(Apply(TypeApply(fn,_), List(code)),nme.apply),List(quotes))
         if fn.symbol == defn.QuotedRuntime_exprQuote =>
           super.transform(tree)(using quoteContext)

sbt-test/scala3-compat/macros-forward-3.0/app/App.scala

@@ -0,0 +1,17 @@
+package app
+
+import lib.*
+
+def powerTest(x: Double): Unit =
+  power(x, 0)
+  power(x, 1)
+  power(x, 5)
+  power(x, 10)
+
+def letTest: Unit =
+  let(0) { _ + 1 }
+  let(0) { _.toString }
+  let((4, 'a')) { _.swap }
+  let(new Foo) { _.hashCode }
+
+class Foo

sbt-test/scala3-compat/macros-forward-3.0/build.sbt

@@ -0,0 +1,14 @@
+lazy val checkOptions = Seq("-Xcheck-macros", "-Ycheck:all", "-Yno-double-bindings")
+
+lazy val lib = project.in(file("lib"))
+  .settings(
+    scalacOptions ++= Seq("-scala-output-version", "3.0") ++ checkOptions
+  )
+
+lazy val app = project.in(file("app"))
+  .dependsOn(lib)
+  .settings(
+    scalaVersion := "3.0.2",
+    scalacOptions ++= checkOptions,
+    dependencyOverrides += scalaOrganization.value %% "scala3-library" % scalaVersion.value,
+  )

sbt-test/scala3-compat/macros-forward-3.0/lib/Macro.scala

@@ -0,0 +1,20 @@
+package lib
+
+import scala.quoted.*
+
+inline def power(x: Double, inline n: Int) = ${ powerCode('x, 'n) }
+
+private def powerCode(x: Expr[Double], n: Expr[Int])(using Quotes): Expr[Double] =
+  unrolledPowerCode(x, n.valueOrError)
+
+private def unrolledPowerCode(x: Expr[Double], n: Int)(using Quotes): Expr[Double] =
+  if n == 0 then '{ 1.0 } // tests simple quotes without splices
+  else if n % 2 == 1 then '{ $x * ${ unrolledPowerCode(x, n - 1) } } // tests simple splices
+  else '{ val y = $x * $x; ${ unrolledPowerCode('y, n / 2) } } // tests splice with term capture
+
+
+inline def let[T, U](x: T)(inline body: T => U): U = ${ letCode('x, 'body) }
+
+private def letCode[T: Type, U: Type](x: Expr[T], body: Expr[T => U])(using Quotes): Expr[U] =
+  // tests use of Type
+  '{ val y: T = $x; $body(y): U }

sbt-test/scala3-compat/macros-forward-3.0/project/DottyInjectedPlugin.scala

@@ -0,0 +1,11 @@
+import sbt._
+import Keys._
+
+object DottyInjectedPlugin extends AutoPlugin {
+  override def requires = plugins.JvmPlugin
+  override def trigger = allRequirements
+
+  override val projectSettings = Seq(
+    scalaVersion := sys.props("plugin.scalaVersion")
+  )
+}

sbt-test/scala3-compat/macros-forward-3.0/test

@@ -0,0 +1 @@
+> app/compile

tests/disabled/pos-macros/forwardCompat-3.0/Macro_1_r3.0.scala

@@ -0,0 +1,20 @@
+import scala.quoted.*
+
+object Macros:
+
+  inline def power(x: Double, inline n: Int) = ${ powerCode('x, 'n) }
+
+  private def powerCode(x: Expr[Double], n: Expr[Int])(using Quotes): Expr[Double] =
+    unrolledPowerCode(x, n.valueOrError)
+
+  private def unrolledPowerCode(x: Expr[Double], n: Int)(using Quotes): Expr[Double] =
+    if n == 0 then '{ 1.0 } // tests simple quotes without splices
+    else if n % 2 == 1 then '{ $x * ${ unrolledPowerCode(x, n - 1) } } // tests simple splices
+    else '{ val y = $x * $x; ${ unrolledPowerCode('y, n / 2) } } // tests splice with term capture
+
+
+  inline def let[T, U](x: T)(inline body: T => U): U = ${ letCode('x, 'body) }
+
+  private def letCode[T: Type, U: Type](x: Expr[T], body: Expr[T => U])(using Quotes): Expr[U] =
+    // tests use of Type
+    '{ val y: T = $x; $body(y): U }

tests/disabled/pos-macros/forwardCompat-3.0/Test_2_c3.0.2.scala

@@ -0,0 +1,15 @@
+import Macros.*
+
+def powerTest(x: Double): Unit =
+  power(x, 0)
+  power(x, 1)
+  power(x, 5)
+  power(x, 10)
+
+def letTest: Unit =
+  let(0) { _ + 1 }
+  let(0) { _.toString }
+  let((4, 'a')) { _.swap }
+  let(new Foo) { _.hashCode }
+
+class Foo

tests/disabled/pos-macros/forwardCompat-3.0/why.md

@@ -0,0 +1,3 @@
+Fails `testCompilation` as if the release flag was not set. But it was and the compile used it.
+
+Manual tests show that this does work.

tests/disabled/pos-macros/forwardCompat-3.1/Macro_1_r3.1.scala

@@ -0,0 +1,20 @@
+import scala.quoted.*
+
+object Macros:
+
+  inline def power(x: Double, inline n: Int) = ${ powerCode('x, 'n) }
+
+  private def powerCode(x: Expr[Double], n: Expr[Int])(using Quotes): Expr[Double] =
+    unrolledPowerCode(x, n.valueOrError)
+
+  private def unrolledPowerCode(x: Expr[Double], n: Int)(using Quotes): Expr[Double] =
+    if n == 0 then '{ 1.0 } // tests simple quotes without splices
+    else if n % 2 == 1 then '{ $x * ${ unrolledPowerCode(x, n - 1) } } // tests simple splices
+    else '{ val y = $x * $x; ${ unrolledPowerCode('y, n / 2) } } // tests splice with term capture
+
+
+  inline def let[T, U](x: T)(inline body: T => U): U = ${ letCode('x, 'body) }
+
+  private def letCode[T: Type, U: Type](x: Expr[T], body: Expr[T => U])(using Quotes): Expr[U] =
+    // tests use of Type
+    '{ val y: T = $x; $body(y): U }

tests/disabled/pos-macros/forwardCompat-3.1/Test_2_c3.1.0.scala

@@ -0,0 +1,15 @@
+import Macros.*
+
+def powerTest(x: Double): Unit =
+  power(x, 0)
+  power(x, 1)
+  power(x, 5)
+  power(x, 10)
+
+def letTest: Unit =
+  let(0) { _ + 1 }
+  let(0) { _.toString }
+  let((4, 'a')) { _.swap }
+  let(new Foo) { _.hashCode }
+
+class Foo

tests/disabled/pos-macros/forwardCompat-3.1/why.md

@@ -0,0 +1 @@
+Disabled until https://github.com/lampepfl/dotty/issues/14306 is fixed