Merge pull request #302 from dotty-staging/fix/returns

Fix/returns

Author: DarkDimius

src/dotty/tools/dotc/core/SymDenotations.scala

@@ -422,7 +422,7 @@ object SymDenotations {
     }
 
     /** Is this a user defined "def" method? Excluded are accessors. */
-    final def isSourceMethod(implicit ctx: Context) = this is (Method, butNot = Accessor)
+    final def isSourceMethod(implicit ctx: Context) = this is (Method, butNot = AccessorOrLabel)
 
     /** Is this a setter? */
     final def isGetter(implicit ctx: Context) =
@@ -1664,4 +1664,6 @@ object SymDenotations {
     private final val NumBits = NumWords << WordSizeLog
     private final val Mask = NumBits - 1
   }
+
+  private val AccessorOrLabel = Accessor | Label
 }

src/dotty/tools/dotc/reporting/ConsoleReporter.scala

@@ -40,16 +40,17 @@ class ConsoleReporter(
     }
   }
 
-  override def doReport(d: Diagnostic)(implicit ctx: Context): Unit = d match {
-    case d: Error =>
-      printMessageAndPos(s"error: ${d.msg}", d.pos)
-      if (ctx.settings.prompt.value) displayPrompt()
-    case d: ConditionalWarning if !d.enablingOption.value =>
-    case d: Warning =>
-      printMessageAndPos(s"warning: ${d.msg}", d.pos)
-    case _ =>
-      printMessageAndPos(d.msg, d.pos)
-  }
+  override def doReport(d: Diagnostic)(implicit ctx: Context): Unit =
+    if (!d.isSuppressed) d match {
+      case d: Error =>
+        printMessageAndPos(s"error: ${d.msg}", d.pos)
+        if (ctx.settings.prompt.value) displayPrompt()
+      case d: ConditionalWarning if !d.enablingOption.value =>
+      case d: Warning =>
+        printMessageAndPos(s"warning: ${d.msg}", d.pos)
+      case _ =>
+        printMessageAndPos(d.msg, d.pos)
+    }
 
   def displayPrompt(): Unit = {
     writer.print("\na)bort, s)tack, r)esume: ")

src/dotty/tools/dotc/reporting/Reporter.scala

@@ -216,7 +216,7 @@ abstract class Reporter {
 
   def report(d: Diagnostic)(implicit ctx: Context): Unit = if (!isHidden(d)) {
     doReport(d)
-    if (!d.isSuppressed) d match {
+    d match {
       case d: ConditionalWarning if !d.enablingOption.value => unreportedWarnings(d.enablingOption.name) += 1
       case d: Warning => warningCount += 1
       case d: Error => errorCount += 1

src/dotty/tools/dotc/transform/TreeTransform.scala

@@ -1141,7 +1141,11 @@ object TreeTransforms {
           if (mutatedInfo eq null) tree
           else {
             val expr = transform(tree.expr, mutatedInfo, cur)
-            val from = transform(tree.from, mutatedInfo, cur)
+            val from = tree.from
+              // don't thansform the `from` part, as this is not a normal ident, but
+              // a pointer to the enclosing method. Transforming this as a normal ident
+              // can go wrong easily. If a transformation is needed, it should be
+              // the responsibility of the transformReturn method to handle this also.
             goReturn(cpy.Return(tree)(expr, from), mutatedInfo.nx.nxTransReturn(cur))
           }
         case tree: Try =>

src/dotty/tools/dotc/typer/Typer.scala

@@ -669,25 +669,36 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   }
 
   def typedReturn(tree: untpd.Return)(implicit ctx: Context): Return = track("typedReturn") {
-    def returnProto(owner: Symbol) =
-      if (owner.isConstructor) defn.UnitType else owner.info.finalResultType
-    def enclMethInfo(cx: Context): (Tree, Type) =
-      if (tree.from.isEmpty) {
-        val owner = cx.owner
-        if (cx == NoContext || owner.isType) {
-          ctx.error("return outside method definition", tree.pos)
-          (EmptyTree, WildcardType)
-        } else if (owner.isSourceMethod)
-          if (owner.isCompleted) {
-            val from = Ident(TermRef(NoPrefix, owner.asTerm))
-            val proto = returnProto(owner)
-            (from, proto)
-          } else (EmptyTree, errorType(d"$owner has return statement; needs result type", tree.pos))
-        else enclMethInfo(cx.outer)
+    def returnProto(owner: Symbol, locals: Scope): Type =
+      if (owner.isConstructor) defn.UnitType
+      else owner.info match {
+        case info: PolyType =>
+          val tparams = locals.toList.takeWhile(_ is TypeParam)
+          assert(info.paramNames.length == tparams.length,
+                 i"return mismatch from $owner, tparams = $tparams, locals = ${locals.toList}%, %")
+          info.instantiate(tparams.map(_.typeRef)).finalResultType
+        case info =>
+          info.finalResultType
       }
-      else
-        (tree.from.asInstanceOf[tpd.Tree], returnProto(tree.from.symbol))
-    val (from, proto) = enclMethInfo(ctx)
+    def enclMethInfo(cx: Context): (Tree, Type) = {
+      val owner = cx.owner
+      if (cx == NoContext || owner.isType) {
+        ctx.error("return outside method definition", tree.pos)
+        (EmptyTree, WildcardType)
+      }
+      else if (owner != cx.outer.owner && owner.isSourceMethod) {
+        if (owner.isCompleted) {
+          val from = Ident(TermRef(NoPrefix, owner.asTerm))
+          val proto = returnProto(owner, cx.scope)
+          (from, proto)
+        }
+        else (EmptyTree, errorType(d"$owner has return statement; needs result type", tree.pos))
+      }
+      else enclMethInfo(cx.outer)
+    }
+    val (from, proto) =
+      if (tree.from.isEmpty) enclMethInfo(ctx)
+      else (tree.from.asInstanceOf[tpd.Tree], WildcardType)
     val expr1 = typedExpr(tree.expr orElse untpd.unitLiteral.withPos(tree.pos), proto)
     assignType(cpy.Return(tree)(expr1, from))
   }