Use compUnitInfo in mirrorSupportsDefaultArguments

Author: EugeneFlesselle

compiler/src/dotty/tools/dotc/core/SymUtils.scala

@@ -16,8 +16,8 @@ import Constants.Constant
 import Annotations.Annotation
 import Phases.*
 import ast.tpd.Literal
-import dotty.tools.tasty.TastyHeaderUnpickler.TastyVersion
 import transform.Mixin
+import dotty.tools.tasty.TastyVersion
 
 import dotty.tools.dotc.transform.sjs.JSSymUtils.sjsNeedsField
 
@@ -120,9 +120,10 @@ class SymUtils:
      */
     def mirrorSupportsDefaultArguments(using Context): Boolean =
       !self.is(JavaDefined) && !self.is(Scala2x) && self.isClass && {
-//        val tastyVersion: TastyVersion = ???
-//        tastyVersion.major == 28 && tastyVersion.minor >= 4
-        true // TODO
+        val compUnitInfo = self.asClass.compUnitInfo
+        compUnitInfo != null && (compUnitInfo.nn.tastyInfo match
+          case None => true // was not loaded from TASTy
+          case Some(TastyInfo(TastyVersion(major, minor, exp), _)) => major == 28 && minor >= 4)
       }
 
     /** Is this an old style implicit conversion?

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

@@ -10,6 +10,7 @@ import NameOps.*
 import Annotations.Annotation
 import typer.ProtoTypes.constrained
 import ast.{tpd, untpd}
+
 import util.Property
 import util.Spans.Span
 import config.Printers.derive
@@ -644,7 +645,7 @@ class SyntheticMembers(thisPhase: DenotTransformer) {
           synthesizeDef(meth, vrefss => body(cls, vrefss.head.head))
       }
     }
-    def overrideMethod(name: TermName, info: Type, cls: Symbol, body: (Symbol, Tree) => Context ?=> Tree): Unit = { // TODO online override if changed
+    def overrideMethod(name: TermName, info: Type, cls: Symbol, body: (Symbol, Tree) => Context ?=> Tree): Unit = {
       val meth = newSymbol(clazz, name, Synthetic | Method | Override, info, coord = clazz.coord)
       meth.enteredAfter(thisPhase)
       newBody = newBody :+ synthesizeExperimentalDef(meth, vrefss => body(cls, vrefss.head.head))
@@ -666,8 +667,9 @@ class SyntheticMembers(thisPhase: DenotTransformer) {
       addParent(defn.Mirror_ProductClass.typeRef)
       addMethod(nme.fromProduct, MethodType(defn.ProductClass.typeRef :: Nil, monoType.typeRef), cls,
         fromProductBody(_, _, optInfo).ensureConforms(monoType.typeRef))  // t4758.scala or i3381.scala are examples where a cast is needed
-      if cls.mirrorSupportsDefaultArguments && cls.primaryConstructor.hasDefaultParams then overrideMethod(
-        nme.defaultArgument, MethodType(defn.IntType :: Nil, defn.AnyType), cls, defaultArgumentBody(_, _, optInfo))
+      if cls.mirrorSupportsDefaultArguments && cls.primaryConstructor.hasDefaultParams then
+        overrideMethod(nme.defaultArgument, MethodType(defn.IntType :: Nil, defn.AnyType), cls,
+          defaultArgumentBody(_, _, optInfo))
     }
     def makeSumMirror(cls: Symbol, optInfo: Option[MirrorImpl.OfSum]) = {
       addParent(defn.Mirror_SumClass.typeRef)

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

@@ -411,8 +411,8 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
       val elemLabels = accessors.map(acc => ConstantType(Constant(acc.name.toString)))
       val elemsLabels = TypeOps.nestedPairs(elemLabels)
 
-      val supportsDefaults = cls.mirrorSupportsDefaultArguments
-      val elemHasDefaults = accessors.map(acc => ConstantType(Constant(supportsDefaults && acc.is(HasDefault))))
+      val elemHasDefaults = accessors.map(acc => 
+        ConstantType(Constant(cls.mirrorSupportsDefaultArguments && acc.is(HasDefault))))
       val elemsHasDefaults = TypeOps.nestedPairs(elemHasDefaults)
 
       val typeElems = tps.getOrElse(accessors.map(mirroredType.resultType.memberInfo(_).widenExpr))