First version of inline scheme

To be done: outer accessors
To be done: error positions

4 files changed, 224 insertions, 5 deletions

diff --git a/src/dotty/tools/dotc/typer/Inliner.scala b/src/dotty/tools/dotc/typer/Inliner.scala
new file mode 100644
index 000000000..852689a75
--- /dev/null
+++ b/src/dotty/tools/dotc/typer/Inliner.scala
@@ -0,0 +1,200 @@
+package dotty.tools
+package dotc
+package typer
+
+import dotty.tools.dotc.ast.Trees.NamedArg
+import dotty.tools.dotc.ast.{Trees, untpd, tpd, TreeTypeMap}
+import Trees._
+import core._
+import Flags._
+import Symbols._
+import Types._
+import Decorators._
+import StdNames.nme
+import Contexts.Context
+import Names.Name
+import SymDenotations.SymDenotation
+import Annotations.Annotation
+import transform.ExplicitOuter
+import config.Printers.inlining
+import ErrorReporting.errorTree
+import util.Attachment
+import collection.mutable
+
+object Inliner {
+  import tpd._
+
+  private class InlinedBody(tree: => Tree) {
+    lazy val body = tree
+  }
+
+  private val InlinedBody = new Attachment.Key[InlinedBody]
+
+  def attachBody(inlineAnnot: Annotation, tree: => Tree)(implicit ctx: Context): Unit =
+    inlineAnnot.tree.putAttachment(InlinedBody, new InlinedBody(tree))
+
+  def inlinedBody(sym: SymDenotation)(implicit ctx: Context): Tree =
+    sym.getAnnotation(defn.InlineAnnot).get.tree
+      .attachment(InlinedBody).body
+
+  private class Typer extends ReTyper {
+    override def typedSelect(tree: untpd.Select, pt: Type)(implicit ctx: Context): Tree = {
+      val acc = tree.symbol
+      super.typedSelect(tree, pt) match {
+        case res @ Select(qual, name) =>
+          if (name.endsWith(nme.OUTER)) {
+            val outerAcc = tree.symbol
+            println(i"selecting $tree / ${acc} / ${qual.tpe.normalizedPrefix}")
+            res.withType(qual.tpe.widen.normalizedPrefix)
+          }
+          else {
+            ensureAccessible(res.tpe, qual.isInstanceOf[Super], tree.pos)
+            res
+          }
+        case res => res
+      }
+    }
+  }
+
+  def inlineCall(tree: Tree, pt: Type)(implicit ctx: Context): Tree = {
+    if (ctx.inlineCount < ctx.settings.xmaxInlines.value) {
+      ctx.inlineCount += 1
+      val rhs = inlinedBody(tree.symbol)
+      val inlined = new Inliner(tree, rhs).inlined
+      try new Typer().typedUnadapted(inlined, pt)
+      finally ctx.inlineCount -= 1
+    } else errorTree(tree,
+      i"""Maximal number of successive inlines (${ctx.settings.xmaxInlines.value}) exceeded,
+                   | Maybe this is caused by a recursive inline method?
+                   | You can use -Xmax:inlines to change the limit.""")
+  }
+}
+
+class Inliner(call: tpd.Tree, rhs: tpd.Tree)(implicit ctx: Context) {
+  import tpd._
+
+  private val meth = call.symbol
+
+  private def decomposeCall(tree: Tree): (Tree, List[Tree], List[List[Tree]]) = tree match {
+    case Apply(fn, args) =>
+      val (meth, targs, argss) = decomposeCall(fn)
+      (meth, targs, argss :+ args)
+    case TypeApply(fn, targs) =>
+      val (meth, Nil, Nil) = decomposeCall(fn)
+      (meth, targs, Nil)
+    case _ =>
+      (tree, Nil, Nil)
+  }
+
+  private val (methPart, targs, argss) = decomposeCall(call)
+
+  private lazy val prefix = methPart match {
+    case Select(qual, _) => qual
+    case _ => tpd.This(ctx.owner.enclosingClass.asClass)
+  }
+
+  private val replacement = new mutable.HashMap[Type, NamedType]
+
+  private val paramBindings = paramBindingsOf(meth.info, targs, argss)
+
+  private def paramBindingsOf(tp: Type, targs: List[Tree], argss: List[List[Tree]]): List[MemberDef] = tp match {
+    case tp: PolyType =>
+      val bindings =
+        (tp.paramNames, targs).zipped.map { (name, arg) =>
+          val tparam = newSym(name, EmptyFlags, TypeAlias(arg.tpe.stripTypeVar)).asType
+          TypeDef(tparam)
+        }
+      bindings ::: paramBindingsOf(tp.resultType, Nil, argss)
+    case tp: MethodType =>
+      val bindings =
+        (tp.paramNames, tp.paramTypes, argss.head).zipped.map { (name, paramtp, arg) =>
+          def isByName = paramtp.dealias.isInstanceOf[ExprType]
+          val (paramFlags, paramType) =
+            if (isByName) (Method, ExprType(arg.tpe)) else (EmptyFlags, arg.tpe)
+          val vparam = newSym(name, paramFlags, paramType).asTerm
+          if (isByName) DefDef(vparam, arg) else ValDef(vparam, arg)
+        }
+      bindings ::: paramBindingsOf(tp.resultType, targs, argss.tail)
+    case _ =>
+      assert(targs.isEmpty)
+      assert(argss.isEmpty)
+      Nil
+  }
+
+  private def newSym(name: Name, flags: FlagSet, info: Type): Symbol =
+    ctx.newSymbol(ctx.owner, name, flags, info, coord = call.pos)
+
+  private def registerType(tpe: Type): Unit =
+    if (!replacement.contains(tpe)) tpe match {
+      case tpe: ThisType =>
+        if (!ctx.owner.isContainedIn(tpe.cls) && !tpe.cls.is(Package))
+          if (tpe.cls.isStaticOwner)
+            replacement(tpe) = tpe.cls.sourceModule.termRef
+          else {
+            def outerDistance(cls: Symbol): Int = {
+              assert(cls.exists, i"not encl: ${meth.owner.enclosingClass} ${tpe.cls}")
+              if (tpe.cls eq cls) 0
+              else outerDistance(cls.owner.enclosingClass) + 1
+            }
+            val n = outerDistance(meth.owner)
+            replacement(tpe) = newSym(nme.SELF ++ n.toString, EmptyFlags, tpe.widen).termRef
+          }
+      case tpe: NamedType if tpe.symbol.is(Param) && tpe.symbol.owner == meth =>
+        val Some(binding) = paramBindings.find(_.name == tpe.name)
+        replacement(tpe) =
+          if (tpe.name.isTypeName) binding.symbol.typeRef else binding.symbol.termRef
+      case _ =>
+    }
+
+  private def registerLeaf(tree: Tree): Unit = tree match {
+    case _: This | _: Ident => registerType(tree.tpe)
+    case _ =>
+  }
+
+  private def outerLevel(sym: Symbol) = sym.name.drop(nme.SELF.length).toString.toInt
+
+  val inlined = {
+    rhs.foreachSubTree(registerLeaf)
+
+    val accessedSelfSyms =
+      (for ((tp: ThisType, ref) <- replacement) yield ref.symbol.asTerm).toSeq.sortBy(outerLevel)
+
+    val outerBindings = new mutable.ListBuffer[MemberDef]
+    for (selfSym <- accessedSelfSyms) {
+      val rhs =
+        if (outerBindings.isEmpty) prefix
+        else {
+          val lastSelf = outerBindings.last.symbol
+          val outerDelta = outerLevel(selfSym) - outerLevel(lastSelf)
+          def outerSelect(ref: Tree, dummy: Int): Tree = ???
+            //ref.select(ExplicitOuter.outerAccessorTBD(ref.tpe.widen.classSymbol.asClass))
+          (ref(lastSelf) /: (0 until outerDelta))(outerSelect)
+        }
+      outerBindings += ValDef(selfSym, rhs.ensureConforms(selfSym.info))
+    }
+    outerBindings ++= paramBindings
+
+    val typeMap = new TypeMap {
+      def apply(t: Type) = t match {
+        case _: SingletonType => replacement.getOrElse(t, t)
+        case _ => mapOver(t)
+      }
+    }
+
+    def treeMap(tree: Tree) = tree match {
+      case _: This | _: Ident =>
+        replacement.get(tree.tpe) match {
+          case Some(t) => ref(t)
+          case None => tree
+        }
+      case _ => tree
+    }
+
+    val inliner = new TreeTypeMap(typeMap, treeMap, meth :: Nil, ctx.owner :: Nil)
+
+    val result = inliner(Block(outerBindings.toList, rhs)).withPos(call.pos)
+
+    inlining.println(i"inlining $call\n --> \n$result")
+    result
+  }
+}
diff --git a/src/dotty/tools/dotc/typer/Namer.scala b/src/dotty/tools/dotc/typer/Namer.scala
index 6eca9be41..06e798bdb 100644
--- a/src/dotty/tools/dotc/typer/Namer.scala
+++ b/src/dotty/tools/dotc/typer/Namer.scala
@@ -566,10 +566,17 @@ class Namer { typer: Typer =>
           val cls = typedAheadAnnotation(annotTree)
           val ann = Annotation.deferred(cls, implicit ctx => typedAnnotation(annotTree))
           denot.addAnnotation(ann)
+          if (cls == defn.InlineAnnot) addInlineInfo(ann, original)
         }
       case _ =>
     }
 
+    private def addInlineInfo(inlineAnnot: Annotation, original: untpd.Tree) = original match {
+      case original: untpd.DefDef =>
+        Inliner.attachBody(inlineAnnot, typedAheadExpr(original).asInstanceOf[tpd.DefDef].rhs)
+      case _ =>
+    }
+
     /** Intentionally left without `implicit ctx` parameter. We need
      *  to pick up the context at the point where the completer was created.
      */
diff --git a/src/dotty/tools/dotc/typer/ReTyper.scala b/src/dotty/tools/dotc/typer/ReTyper.scala
index 9750957bf..03b415a6f 100644
--- a/src/dotty/tools/dotc/typer/ReTyper.scala
+++ b/src/dotty/tools/dotc/typer/ReTyper.scala
@@ -10,7 +10,7 @@ import typer.ProtoTypes._
 import ast.{tpd, untpd}
 import ast.Trees._
 import scala.util.control.NonFatal
-import config.Printers
+import config.Printers.typr
 
 /** A version of Typer that keeps all symbols defined and referenced in a
  *  previously typed tree.
@@ -87,7 +87,7 @@ class ReTyper extends Typer {
     try super.typedUnadapted(tree, pt)
     catch {
       case NonFatal(ex) =>
-        println(i"exception while typing $tree of class ${tree.getClass} # ${tree.uniqueId}")
+        typr.println(i"exception while typing $tree of class ${tree.getClass} # ${tree.uniqueId}")
         throw ex
     }
 
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 562af75f6..007eaa468 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -885,12 +885,15 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         (EmptyTree, WildcardType)
       }
       else if (owner != cx.outer.owner && owner.isRealMethod) {
-        if (owner.isCompleted) {
+        if (owner.isInlineMethod)
+          (EmptyTree, errorType(em"no explicit return allowed from inline $owner", tree.pos))
+        else if (!owner.isCompleted)
+          (EmptyTree, errorType(em"$owner has return statement; needs result type", tree.pos))
+        else {
           val from = Ident(TermRef(NoPrefix, owner.asTerm))
           val proto = returnProto(owner, cx.scope)
           (from, proto)
         }
-        else (EmptyTree, errorType(em"$owner has return statement; needs result type", tree.pos))
       }
       else enclMethInfo(cx.outer)
     }
@@ -1154,6 +1157,13 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         rhsCtx.gadt.setBounds(tdef.symbol, TypeAlias(tparam.typeRef)))
     }
     val rhs1 = typedExpr(ddef.rhs, tpt1.tpe)(rhsCtx)
+
+    // Overwrite inline body to make sure it is not evaluated twice
+    sym.getAnnotation(defn.InlineAnnot) match {
+      case Some(ann) => Inliner.attachBody(ann, rhs1)
+      case _ =>
+    }
+
     if (sym.isAnonymousFunction) {
       // If we define an anonymous function, make sure the return type does not
       // refer to parameters. This is necessary because closure types are
@@ -1773,7 +1783,9 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
           tree
         }
         else if (tree.tpe <:< pt)
-          if (ctx.typeComparer.GADTused && pt.isValueType)
+          if (tree.symbol.isInlineMethod && !ctx.owner.ownersIterator.exists(_.isInlineMethod))
+            adapt(Inliner.inlineCall(tree, pt), pt)
+          else if (ctx.typeComparer.GADTused && pt.isValueType)
             // Insert an explicit cast, so that -Ycheck in later phases succeeds.
             // I suspect, but am not 100% sure that this might affect inferred types,
             // if the expected type is a supertype of the GADT bound. It would be good to come