Handle outer this in Inliner

Also, do some refactorings and fix some bugs in Inliner.

4 files changed, 10 insertions, 3 deletions

diff --git a/src/dotty/tools/dotc/transform/ExplicitOuter.scala b/src/dotty/tools/dotc/transform/ExplicitOuter.scala
index 60ef1b306..3f235dca7 100644
--- a/src/dotty/tools/dotc/transform/ExplicitOuter.scala
+++ b/src/dotty/tools/dotc/transform/ExplicitOuter.scala
@@ -57,6 +57,12 @@ class ExplicitOuter extends MiniPhaseTransform with InfoTransformer { thisTransf
 
   override def mayChange(sym: Symbol)(implicit ctx: Context): Boolean = sym.isClass
 
+  /** Convert a selection of the form `qual.C_<OUTER>` to an outer path from `qual` to `C` */
+  override def transformSelect(tree: Select)(implicit ctx: Context, info: TransformerInfo) =
+    if (tree.name.isOuterSelect)
+      outer.path(tree.tpe.widen.classSymbol, tree.qualifier).ensureConforms(tree.tpe)
+    else tree
+
   /** First, add outer accessors if a class does not have them yet and it references an outer this.
    *  If the class has outer accessors, implement them.
    *  Furthermore, if a parent trait might have an outer accessor,
diff --git a/src/dotty/tools/dotc/transform/FirstTransform.scala b/src/dotty/tools/dotc/transform/FirstTransform.scala
index 6e1fed607..74dc9b9d6 100644
--- a/src/dotty/tools/dotc/transform/FirstTransform.scala
+++ b/src/dotty/tools/dotc/transform/FirstTransform.scala
@@ -72,8 +72,8 @@ class FirstTransform extends MiniPhaseTransform with InfoTransformer with Annota
 
   override def checkPostCondition(tree: Tree)(implicit ctx: Context): Unit = {
     tree match {
-      case Select(qual, _) if tree.symbol.exists =>
-        assert(qual.tpe derivesFrom tree.symbol.owner, i"non member selection of ${tree.symbol.showLocated} from ${qual.tpe}")
+      case Select(qual, name) if !name.isOuterSelect && tree.symbol.exists =>
+        assert(qual.tpe derivesFrom tree.symbol.owner, i"non member selection of ${tree.symbol.showLocated} from ${qual.tpe} in $tree")
       case _: TypeTree =>
       case _: Import | _: NamedArg | _: TypTree =>
         assert(false, i"illegal tree: $tree")
diff --git a/src/dotty/tools/dotc/transform/PatternMatcher.scala b/src/dotty/tools/dotc/transform/PatternMatcher.scala
index 490feb7d0..49c0eabec 100644
--- a/src/dotty/tools/dotc/transform/PatternMatcher.scala
+++ b/src/dotty/tools/dotc/transform/PatternMatcher.scala
@@ -782,6 +782,7 @@ class PatternMatcher extends MiniPhaseTransform with DenotTransformer {
 
           val expectedClass = expectedTp.dealias.classSymbol.asClass
           val test = codegen._asInstanceOf(testedBinder, expectedTp)
+          // TODO: Use nme.OUTER_SELECT, like the Inliner does?
           val outerAccessorTested = ctx.atPhase(ctx.explicitOuterPhase.next) { implicit ctx =>
             ExplicitOuter.ensureOuterAccessors(expectedClass)
             test.select(ExplicitOuter.outerAccessor(expectedClass)).select(defn.Object_eq).appliedTo(expectedOuter)
diff --git a/src/dotty/tools/dotc/transform/SuperAccessors.scala b/src/dotty/tools/dotc/transform/SuperAccessors.scala
index 6af991f27..10be6db65 100644
--- a/src/dotty/tools/dotc/transform/SuperAccessors.scala
+++ b/src/dotty/tools/dotc/transform/SuperAccessors.scala
@@ -148,7 +148,7 @@ class SuperAccessors(thisTransformer: DenotTransformer) {
      */
     private def ensureProtectedAccessOK(sel: Select, targs: List[Tree])(implicit ctx: Context) = {
       val sym = sel.symbol
-      if (sym.exists && needsProtectedAccessor(sym, sel.pos)) {
+      if (sym.isTerm && !sel.name.isOuterSelect && needsProtectedAccessor(sym, sel.pos)) {
         ctx.debuglog("Adding protected accessor for " + sel)
         protectedAccessorCall(sel, targs)
       } else sel