Handle retained inline bodies for methods with @TargetNAME annotations

Author: odersky

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

@@ -936,9 +936,17 @@ object Erasure {
         case stat: DefDef @unchecked if stat.symbol.name.is(BodyRetainerName) =>
           val retainer = stat.symbol
           val origName = retainer.name.asTermName.exclude(BodyRetainerName)
+          val targetName =
+            if retainer.hasAnnotation(defn.TargetNameAnnot) then
+              try retainer.erasedName
+              finally
+                 // reset target name so that definition will have a BodyRetainerName
+                 // after erasure and be thereby eliminated in typedDefDef
+                retainer.setTargetName(retainer.name)
+            else origName
           val inlineMeth = atPhase(typerPhase) {
             retainer.owner.info.decl(origName)
-              .matchingDenotation(retainer.owner.thisType, stat.symbol.info)
+              .matchingDenotation(retainer.owner.thisType, stat.symbol.info, targetName)
               .symbol
           }
           (inlineMeth, stat)

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

@@ -87,7 +87,7 @@ class SuperAccessors(thisPhase: DenotTransformer) {
         val acc = newSymbol(
             clazz, superName, Artifact | Method | maybeDeferred,
             superInfo, coord = accRange).enteredAfter(thisPhase)
-        if !Denotations.targetNamesMatch(sym.name, sym.erasedName) then
+        if sym.hasAnnotation(defn.TargetNameAnnot) then
           acc.addAnnotation(
             Annotation(defn.TargetNameAnnot,
               Literal(Constant(superAccessorName(sym.erasedName).toString)).withSpan(sym.span)))

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

@@ -198,6 +198,8 @@ object Inliner {
       name = BodyRetainerName(meth.name),
       flags = meth.flags &~ (Inline | Macro | Override) | Private,
       coord = mdef.rhs.span.startPos).asTerm
+    for targetAnnot <- meth.getAnnotation(defn.TargetNameAnnot) do
+      retainer.addAnnotation(targetAnnot)
     polyDefDef(retainer, targs => prefss =>
       inlineCall(
         ref(meth).appliedToTypes(targs).appliedToArgss(prefss)

tests/run/inline-override.check

@@ -3,3 +3,5 @@ inline 22
 inline 22
 inline 22
 inline 22
+inline 22
+inline 22

tests/run/inline-override.scala

@@ -1,22 +1,28 @@
+import annotation.targetName
+
 abstract class A:
   def f(x: Int) = s"dynamic $x"
   def h(x: Int): String
+  @targetName("h2") def h1(x: Int): String
   inline def i(x: Int): String
 
 class B extends A:
   inline override def f(x: Int) = g(x)
   inline def g(x: Int) = s"inline $x"
   inline def h(x: Int) = g(x)
+  @targetName("h2") inline def h1(x: Int) = g(x)
   inline def i(x: Int) = g(x)
 
 @main def Test =
   val b = B()
   println(b.f(22))
   println(b.h(22))
+  println(b.h1(22))
   println(b.i(22))
   val a: A = b
   println(a.f(22))
   println(a.h(22))
+  println(a.h1(22))
 //  println(a.i(22))