WIP

Author: HarrisL2

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

@@ -36,6 +36,8 @@ import core.Mode
 import util.Property
 import reporting.*
 import scala.annotation.tailrec
+import core.Annotations.*
+import ast.Trees.*
 
 class Erasure extends Phase with DenotTransformer {
 
@@ -926,7 +928,18 @@ object Erasure {
      *  with more than `MaxImplementedFunctionArity` parameters to use a single
      *  parameter of type `[]Object`.
      */
-    override def typedDefDef(ddef: untpd.DefDef, sym: Symbol)(using Context): Tree =
+    override def typedDefDef(ddef: untpd.DefDef, sym: Symbol)(using Context): Tree = trace(i"typedDefDef $sym,"+s" ${atPhase(ctx.phaseId-1)(sym.info)}") {// Possible Annotation target
+      atPhase(ctx.phaseId-1)(sym.info) match
+        case pt: PolyType =>
+          def toTypeB(tp: Type): TypeB = tp match
+            case tpr: TypeParamRef => TypeB.M(tpr.paramNum)
+            case _ => TypeB.None
+          pt.resType match
+            case mt: MethodType =>
+              sym.addAnnotation(ErasedInfo(pt.paramInfos.size, mt.paramInfos.map(toTypeB), toTypeB(mt.resType)))
+            case other =>
+              sym.addAnnotation(ErasedInfo(pt.paramInfos.size, Nil, toTypeB(other.widenExpr)))
+        case _ => ()
       if sym.isEffectivelyErased || sym.name.is(BodyRetainerName) then
         erasedDef(sym)
       else
@@ -970,6 +983,7 @@ object Erasure {
           tpt = untpd.TypedSplice(TypeTree(restpe).withSpan(ddef.tpt.span)),
           rhs = rhs1)
         super.typedDefDef(ddef1, sym)
+    }
     end typedDefDef
 
     /** The outer parameter definition of a constructor if it needs one */
@@ -1109,3 +1123,17 @@ object Erasure {
   private def takesBridges(sym: Symbol)(using Context): Boolean =
     sym.isClass && !sym.isOneOf(Flags.Trait | Flags.Package)
 }
+
+enum TypeB:
+  case None
+  case M(x: Int)
+// case class TypeB(tp: Type)
+
+class ErasedInfo(paramCount: Int, paramType: List[TypeB], returnType: TypeB) extends Annotation {
+  override def tree(using Context) =
+    tpd.New(defn.SourceFileAnnot.typeRef,
+            List(tpd.Literal(Constant(toString))))
+
+  override def toString =
+    s"$paramCount, $paramType, $returnType"
+}