Fix inherited default params.

Author: sjrd

compiler/src/dotty/tools/backend/sjs/JSExportsGen.scala

@@ -541,22 +541,8 @@ final class JSExportsGen(jsCodeGen: JSCodeGen)(using Context) {
       previousArgsValues: Int => List[js.Tree])(
       implicit pos: SourcePosition): js.Tree = {
 
-    val targetSym = {
-      if (sym.isClassConstructor) {
-        /*/* Get the companion module class.
-         * For inner classes the sym.owner.companionModule can be broken,
-         * therefore companionModule is fetched at uncurryPhase.
-         */
-        val companionModule = enteringPhase(currentRun.namerPhase) {
-          sym.owner.companionModule
-        }
-        companionModule.moduleClass*/
-        sym.owner.companionModule.moduleClass
-      } else {
-        sym.owner
-      }
-    }
-    val defaultGetterDenot = targetSym.info.member(DefaultGetterName(sym.name.asTermName, paramIndex))
+    val targetSym = targetSymForDefaultGetter(sym)
+    val defaultGetterDenot = this.defaultGetterDenot(targetSym, sym, paramIndex)
 
     assert(defaultGetterDenot.exists, s"need default getter for method ${sym.fullName}")
     assert(!defaultGetterDenot.isOverloaded, i"found overloaded default getter $defaultGetterDenot")
@@ -584,6 +570,28 @@ final class JSExportsGen(jsCodeGen: JSCodeGen)(using Context) {
     }
   }
 
+  private def targetSymForDefaultGetter(sym: Symbol): Symbol = {
+    if (sym.isClassConstructor) {
+      /*/* Get the companion module class.
+       * For inner classes the sym.owner.companionModule can be broken,
+       * therefore companionModule is fetched at uncurryPhase.
+       */
+      val companionModule = enteringPhase(currentRun.namerPhase) {
+        sym.owner.companionModule
+      }
+      companionModule.moduleClass*/
+      sym.owner.companionModule.moduleClass
+    } else {
+      sym.owner
+    }
+  }
+
+  private def defaultGetterDenot(targetSym: Symbol, sym: Symbol, paramIndex: Int): Denotation =
+    targetSym.info.member(DefaultGetterName(sym.name.asTermName, paramIndex))
+
+  private def defaultGetterDenot(sym: Symbol, paramIndex: Int): Denotation =
+    defaultGetterDenot(targetSymForDefaultGetter(sym), sym, paramIndex)
+
   /** Generate the final forwarding call to the exported method. */
   private def genResult(exported: Exported, args: List[js.Tree], static: Boolean)(
       implicit pos: SourcePosition): js.Tree = {
@@ -626,15 +634,12 @@ final class JSExportsGen(jsCodeGen: JSCodeGen)(using Context) {
   }
 
   private object ParamSpec {
-    def forSyntheticParam(sym: Symbol): ParamSpec = {
-      // Synthetic params are never repeated nor have a default value
-      new ParamSpec(sym, sym.info, isRepeated = false, hasDefault = false)
-    }
-
-    def apply(sym: Symbol, infoAtElimRepeated: Type, infoAtElimEVT: Type): ParamSpec = {
+    def apply(methodSym: Symbol, sym: Symbol, infoAtElimRepeated: Type, infoAtElimEVT: Type,
+        methodHasDefaultParams: Boolean, paramIndex: Int): ParamSpec = {
       val isRepeated = infoAtElimRepeated.isRepeatedParam
       val info = if (isRepeated) infoAtElimRepeated.repeatedToSingle else infoAtElimEVT
-      new ParamSpec(sym, info, isRepeated, sym.is(HasDefault))
+      val hasDefault = methodHasDefaultParams && defaultGetterDenot(methodSym, paramIndex).exists
+      new ParamSpec(sym, info, isRepeated, hasDefault)
     }
   }
 
@@ -651,18 +656,18 @@ final class JSExportsGen(jsCodeGen: JSCodeGen)(using Context) {
       val paramNamessNow = sym.info.paramNamess
       val paramInfosNow = sym.info.paramInfoss.flatten
       val paramSymsAtElimRepeated = atPhase(elimRepeatedPhase)(sym.paramSymss.flatten.filter(_.isTerm))
-      val (paramNamessAtElimRepeated, paramInfosAtElimRepeated) =
-        atPhase(elimRepeatedPhase)((sym.info.paramNamess, sym.info.paramInfoss.flatten))
+      val (paramNamessAtElimRepeated, paramInfosAtElimRepeated, methodHasDefaultParams) =
+        atPhase(elimRepeatedPhase)((sym.info.paramNamess, sym.info.paramInfoss.flatten, sym.hasDefaultParams))
       val (paramNamessAtElimEVT, paramInfosAtElimEVT) =
         atPhase(elimErasedValueTypePhase)((sym.info.paramNamess, sym.info.paramInfoss.flatten))
 
       def buildFormalParams(paramSyms: List[Symbol], paramInfosAtElimRepeated: List[Type],
           paramInfosAtElimEVT: List[Type]): IndexedSeq[ParamSpec] = {
         (for {
-          (paramSym, infoAtElimRepeated, infoAtElimEVT) <-
-            paramSyms.lazyZip(paramInfosAtElimRepeated).lazyZip(paramInfosAtElimEVT)
+          (paramSym, infoAtElimRepeated, infoAtElimEVT, paramIndex) <-
+            paramSyms.lazyZip(paramInfosAtElimRepeated).lazyZip(paramInfosAtElimEVT).lazyZip(0 until paramSyms.size)
         } yield {
-          ParamSpec(paramSym, infoAtElimRepeated, infoAtElimEVT)
+          ParamSpec(sym, paramSym, infoAtElimRepeated, infoAtElimEVT, methodHasDefaultParams, paramIndex)
         }).toIndexedSeq
       }