Call super before matching in Tree-/TypeMap

Override some properties of Inliner that hinder the work of the inline trait inliner. Some of the work done in the Inliner works only for method calls, not for bodies

Author: timotheeandres

compiler/src/dotty/tools/dotc/inlines/Inliner.scala

@@ -115,9 +115,10 @@ object Inliner:
       oldOwners: List[Symbol],
       newOwners: List[Symbol],
       substFrom: List[Symbol],
-      substTo: List[Symbol])(using Context)
+      substTo: List[Symbol],
+      val inlineCopier: TreeCopier)(using Context)
     extends TreeTypeMap(
-      typeMap, treeMap, oldOwners, newOwners, substFrom, substTo, InlineCopier()):
+      typeMap, treeMap, oldOwners, newOwners, substFrom, substTo, inlineCopier):
 
     override def copy(
         typeMap: Type => Type,
@@ -126,7 +127,7 @@ object Inliner:
         newOwners: List[Symbol],
         substFrom: List[Symbol],
         substTo: List[Symbol])(using Context) =
-      new InlinerMap(typeMap, treeMap, oldOwners, newOwners, substFrom, substTo)
+      new InlinerMap(typeMap, treeMap, oldOwners, newOwners, substFrom, substTo, inlineCopier)
 
     override def transformInlined(tree: Inlined)(using Context) =
       if tree.call.isEmpty then
@@ -565,6 +566,7 @@ class Inliner(val call: tpd.Tree)(using Context):
 
   protected def substFrom: List[Symbol] = Nil
   protected def substTo: List[Symbol] = Nil
+  protected def inlineCopier: TreeCopier = InlineCopier()
 
   protected def inlineCtx(inlineTyper: InlineTyper)(using Context): Context =
     inlineContext(call).fresh.setTyper(inlineTyper).setNewScope
@@ -624,7 +626,8 @@ class Inliner(val call: tpd.Tree)(using Context):
       oldOwners = inlinedMethod :: Nil,
       newOwners = ctx.owner :: Nil,
       substFrom = substFrom,
-      substTo = substTo
+      substTo = substTo,
+      inlineCopier = inlineCopier
     )(using inlineCtx)
 
     inlining.println(

compiler/src/dotty/tools/dotc/inlines/Inlines.scala

@@ -533,29 +533,32 @@ object Inlines:
     end expandDefs
 
     protected class InlineTraitTypeMap extends InlinerTypeMap {
-      override def apply(t: Type) = t match {
-        case t: ThisType if t.cls == parentSym => ctx.owner.thisType
-        case t => super.apply(t)
+      override def apply(t: Type) = super.apply(t) match {
+        case t: ThisType if t.cls == parentSym =>
+          ctx.owner.thisType
+        case t =>
+          mapOver(t)
       }
     }
 
     protected class InlineTraitTreeMap extends InlinerTreeMap {
-      override def apply(tree: Tree) = tree match {
-        case tree: This if tree.qual.name == parentSym.name =>
-          Inlined(EmptyTree, Nil, This(ctx.owner.asClass).withSpan(parent.span)).withSpan(tree.span)
+      override def apply(tree: Tree) = super.apply(tree) match {
+        case tree: This if tree.symbol == parentSym =>
+          Inlined(EmptyTree, Nil, This(ctx.owner.asClass).withSpan(parent.span)).withSpan(parent.span)
         case tree: This =>
           tree.tpe match {
             case thisTpe: ThisType if thisTpe.cls.isInlineTrait =>
-              integrate(This(ctx.owner.asClass).withSpan(call.span), thisTpe.cls)
-            case _ => super.apply(tree)
+              integrate(This(ctx.owner.asClass).withSpan(parent.span), thisTpe.cls)
+            case _ =>
+              tree
           }
         case Select(qual, name) =>
           paramAccessorsMapper.getParamAccessorName(qual.symbol, name) match {
-            case Some(newName) => Select(apply(qual), newName).withSpan(tree.span)
-            case None => super.apply(tree)
+            case Some(newName) => Select(this(qual), newName).withSpan(parent.span)
+            case None => Select(this(qual), name)
           }
         case tree =>
-          super.apply(tree)
+          tree
       }
     }
 
@@ -564,6 +567,11 @@ object Inlines:
 
     override protected def substFrom: List[Symbol] = innerClassNewSyms.keys.toList
     override protected def substTo: List[Symbol] = innerClassNewSyms.values.toList
+    override protected def inlineCopier: tpd.TreeCopier = new TypedTreeCopier() {
+      // FIXME it feels weird... Is this correct?
+      override def Apply(tree: Tree)(fun: Tree, args: List[Tree])(using Context): Apply =
+        untpd.cpy.Apply(tree)(fun, args).withTypeUnchecked(tree.tpe)
+    }
 
     override protected def computeThisBindings(): Unit = ()
     override protected def canElideThis(tpe: ThisType): Boolean = true