Merge pull request #13383 from dotty-staging/scalajs-1.7.0

Upgrade to Scala.js 1.7.0.

Author: nicolasstucki

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

@@ -1067,7 +1067,8 @@ class JSCodeGen()(using genCtx: Context) {
       val jsClassCaptures = List.newBuilder[js.ParamDef]
 
       def add(tree: ConstructorTree[_ <: JSCtor]): Unit = {
-        val (e, c) = genJSClassCtorDispatch(tree.ctor.sym, tree.ctor.params, tree.overloadNum)
+        val (e, c) = genJSClassCtorDispatch(tree.ctor.sym,
+            tree.ctor.paramsAndInfo, tree.overloadNum)
         exports += e
         jsClassCaptures ++= c
         tree.subCtors.foreach(add(_))
@@ -1133,16 +1134,19 @@ class JSCodeGen()(using genCtx: Context) {
     assert(jsSuperCall.isDefined,
         s"Did not find Super call in primary JS construtor at ${dd.sourcePos}")
 
-    val params = dd.paramss.flatten.map(_.symbol)
-
-    new PrimaryJSCtor(sym, params, jsSuperCall.get :: jsStats.result())
+    new PrimaryJSCtor(sym, genParamsAndInfo(sym, dd.paramss), jsSuperCall.get :: jsStats.result())
   }
 
   private def genSecondaryJSClassCtor(dd: DefDef): SplitSecondaryJSCtor = {
     val sym = dd.symbol
-    val Block(stats, _) = dd.rhs
     assert(!sym.isPrimaryConstructor, s"called with primary ctor $sym")
 
+    def flattenBlocks(t: Tree): List[Tree] = t match {
+      case Block(stats, expr) => (stats :+ expr).flatMap(flattenBlocks)
+      case _                  => t :: Nil
+    }
+    val stats = flattenBlocks(dd.rhs)
+
     val beforeThisCall = List.newBuilder[js.Tree]
     var thisCall: Option[(Symbol, List[js.Tree])] = None
     val afterThisCall = List.newBuilder[js.Tree]
@@ -1167,24 +1171,33 @@ class JSCodeGen()(using genCtx: Context) {
       }
     }
 
+    assert(thisCall.isDefined,
+        i"could not find the this() call in secondary JS constructor at ${dd.sourcePos}:\n${stats.map(_.show).mkString("\n")}")
     val Some((targetCtor, ctorArgs)) = thisCall
 
-    val params = dd.paramss.flatten.map(_.symbol)
+    new SplitSecondaryJSCtor(sym, genParamsAndInfo(sym, dd.paramss),
+        beforeThisCall.result(), targetCtor, ctorArgs, afterThisCall.result())
+  }
+
+  private def genParamsAndInfo(ctorSym: Symbol,
+      vparamss: List[ParamClause]): List[(Symbol, JSParamInfo)] = {
+    implicit val pos: SourcePosition = ctorSym.sourcePos
 
-    new SplitSecondaryJSCtor(sym, params, beforeThisCall.result(), targetCtor,
-        ctorArgs, afterThisCall.result())
+    val paramSyms = if (vparamss.isEmpty) Nil else vparamss.head.map(_.symbol)
+    paramSyms.zip(ctorSym.jsParamInfos)
   }
 
-  private def genJSClassCtorDispatch(sym: Symbol, allParams: List[Symbol],
+  private def genJSClassCtorDispatch(ctorSym: Symbol,
+      allParamsAndInfos: List[(Symbol, JSParamInfo)],
       overloadNum: Int): (jsExportsGen.Exported, List[js.ParamDef]) = {
 
-    implicit val pos: SourcePosition = sym.sourcePos
+    implicit val pos: SourcePosition = ctorSym.sourcePos
 
     /* `allParams` are the parameters as seen from inside the constructor body,
      * i.e., the ones generated by the trees in the constructor body.
      */
     val (captureParamsAndInfos, normalParamsAndInfos) =
-      allParams.zip(sym.jsParamInfos).partition(_._2.capture)
+      allParamsAndInfos.partition(_._2.capture)
 
     /* For class captures, we need to generate different names than the ones
      * used by the constructor body. This is necessary so that we can forward
@@ -1203,13 +1216,14 @@ class JSCodeGen()(using genCtx: Context) {
 
     val normalInfos = normalParamsAndInfos.map(_._2).toIndexedSeq
 
-    val jsExport = new jsExportsGen.Exported(sym, normalInfos) {
+    val jsExport = new jsExportsGen.Exported(ctorSym, normalInfos) {
       def genBody(formalArgsRegistry: jsExportsGen.FormalArgsRegistry): js.Tree = {
         val paramAssigns = for {
           ((param, info), i) <- normalParamsAndInfos.zipWithIndex
         } yield {
-          val rhs = jsExportsGen.genScalaArg(this, i, formalArgsRegistry, info, static = true)(
-              prevArgsCount => allParams.take(prevArgsCount).map(genVarRef(_)))
+          val rhs = jsExportsGen.genScalaArg(this, i, formalArgsRegistry, info, static = true,
+              captures = captureParamsAndInfos.map(pi => genVarRef(pi._1)))(
+              prevArgsCount => normalParamsAndInfos.take(prevArgsCount).map(pi => genVarRef(pi._1)))
 
           js.Assign(genVarRef(param), rhs)
         }
@@ -1256,40 +1270,58 @@ class JSCodeGen()(using genCtx: Context) {
      */
 
     def preStats(tree: ConstructorTree[SplitSecondaryJSCtor],
-        nextParams: List[Symbol]): js.Tree = {
-      assert(tree.ctor.ctorArgs.size == nextParams.size, "param count mismatch")
+        nextParamsAndInfo: List[(Symbol, JSParamInfo)]): js.Tree = {
+      val inner = tree.subCtors.map(preStats(_, tree.ctor.paramsAndInfo))
 
-      val inner = tree.subCtors.map(preStats(_, tree.ctor.params))
+      assert(tree.ctor.ctorArgs.size == nextParamsAndInfo.size, "param count mismatch")
+      val paramsInfosAndArgs = nextParamsAndInfo.zip(tree.ctor.ctorArgs)
 
-      /* Reject undefined params (i.e. using a default value of another
-       * constructor) via implementation restriction.
-       *
-       * This is mostly for historical reasons. The ideal solution here would
-       * be to recognize calls to default param getters of JS class
-       * constructors and not even translate them to UndefinedParam in the
-       * first place.
-       */
-      def isUndefinedParam(tree: js.Tree): Boolean = tree match {
-        case js.Transient(UndefinedParam) => true
-        case _                            => false
-      }
+      val (captureParamsInfosAndArgs, normalParamsInfosAndArgs) =
+        paramsInfosAndArgs.partition(_._1._2.capture)
 
-      if (tree.ctor.ctorArgs.exists(isUndefinedParam)) {
-        report.error(
-            "Implementation restriction: " +
-            "in a JS class, a secondary constructor calling another constructor " +
-            "with default parameters must provide the values of all parameters.",
-            tree.ctor.sym.sourcePos)
+      val captureAssigns = for {
+        ((param, _), arg) <- captureParamsInfosAndArgs
+      } yield {
+        js.Assign(genVarRef(param), arg)
       }
 
-      val assignments = for {
-        (param, arg) <- nextParams.zip(tree.ctor.ctorArgs)
-        if !isUndefinedParam(arg)
+      val normalAssigns = for {
+        (((param, info), arg), i) <- normalParamsInfosAndArgs.zipWithIndex
       } yield {
-        js.Assign(genVarRef(param), arg)
+        val newArg = arg match {
+          case js.Transient(UndefinedParam) =>
+            /* Go full circle: We have ignored the default param getter for
+             * this, we'll create it again.
+             *
+             * This seems not optimal: We could simply not ignore the calls to
+             * default param getters in the first place.
+             *
+             * However, this proves to be difficult: Because of translations in
+             * earlier phases, calls to default param getters may be assigned
+             * to temporary variables first (see the undefinedDefaultParams
+             * ScopedVar). If this happens, it becomes increasingly difficult
+             * to distinguish a default param getter call for a constructor
+             * call of *this* instance (in which case we would want to keep
+             * the default param getter call) from one for a *different*
+             * instance (in which case we would want to discard the default
+             * param getter call)
+             *
+             * Because of this, it ends up being easier to just re-create the
+             * default param getter call if necessary.
+             */
+            implicit val pos: SourcePosition = tree.ctor.sym.sourcePos
+            jsExportsGen.genCallDefaultGetter(tree.ctor.sym, i, static = false,
+                captures = captureParamsInfosAndArgs.map(p => genVarRef(p._1._1)))(
+                prevArgsCount => normalParamsInfosAndArgs.take(prevArgsCount).map(p => genVarRef(p._1._1)))
+
+          case arg => arg
+        }
+
+        js.Assign(genVarRef(param), newArg)
       }
 
-      ifOverload(tree, js.Block(inner ++ tree.ctor.beforeCall ++ assignments))
+      ifOverload(tree, js.Block(
+          inner ++ tree.ctor.beforeCall ++ captureAssigns ++ normalAssigns))
     }
 
     def postStats(tree: ConstructorTree[SplitSecondaryJSCtor]): js.Tree = {
@@ -1301,22 +1333,24 @@ class JSCodeGen()(using genCtx: Context) {
     val secondaryCtorTrees = ctorTree.subCtors
 
     js.Block(
-        secondaryCtorTrees.map(preStats(_, primaryCtor.params)) ++
+        secondaryCtorTrees.map(preStats(_, primaryCtor.paramsAndInfo)) ++
         primaryCtor.body ++
         secondaryCtorTrees.map(postStats(_))
     )
   }
 
   private sealed trait JSCtor {
     val sym: Symbol
-    val params: List[Symbol]
+    val paramsAndInfo: List[(Symbol, JSParamInfo)]
   }
 
   private class PrimaryJSCtor(val sym: Symbol,
-      val params: List[Symbol], val body: List[js.Tree]) extends JSCtor
+      val paramsAndInfo: List[(Symbol, JSParamInfo)],
+      val body: List[js.Tree]) extends JSCtor
 
   private class SplitSecondaryJSCtor(val sym: Symbol,
-      val params: List[Symbol], val beforeCall: List[js.Tree],
+      val paramsAndInfo: List[(Symbol, JSParamInfo)],
+      val beforeCall: List[js.Tree],
       val targetCtor: Symbol, val ctorArgs: List[js.Tree],
       val afterCall: List[js.Tree]) extends JSCtor
 
@@ -3158,7 +3192,7 @@ class JSCodeGen()(using genCtx: Context) {
       case resType           => resType
     }
 
-    var clauses: List[(List[js.Tree], js.Tree)] = Nil
+    var clauses: List[(List[js.MatchableLiteral], js.Tree)] = Nil
     var optDefaultClause: Option[js.Tree] = None
 
     for (caze @ CaseDef(pat, guard, body) <- cases) {
@@ -3167,19 +3201,29 @@ class JSCodeGen()(using genCtx: Context) {
 
       val genBody = genStatOrExpr(body, isStat)
 
+      def invalidCase(): Nothing =
+        abortMatch("Invalid case")
+
+      def genMatchableLiteral(tree: Literal): js.MatchableLiteral = {
+        genExpr(tree) match {
+          case matchableLiteral: js.MatchableLiteral => matchableLiteral
+          case otherExpr                             => invalidCase()
+        }
+      }
+
       pat match {
         case lit: Literal =>
-          clauses = (List(genExpr(lit)), genBody) :: clauses
+          clauses = (List(genMatchableLiteral(lit)), genBody) :: clauses
         case Ident(nme.WILDCARD) =>
           optDefaultClause = Some(genBody)
         case Alternative(alts) =>
           val genAlts = alts.map {
-            case lit: Literal => genExpr(lit)
-            case _            => abortMatch("Invalid case in alternative")
+            case lit: Literal => genMatchableLiteral(lit)
+            case _            => invalidCase()
           }
           clauses = (genAlts, genBody) :: clauses
         case _ =>
-          abortMatch("Invalid case pattern")
+          invalidCase()
       }
     }
 
@@ -3194,10 +3238,6 @@ class JSCodeGen()(using genCtx: Context) {
      * case is a typical product of `match`es that are full of
      * `case n if ... =>`, which are used instead of `if` chains for
      * convenience and/or readability.
-     *
-     * When no optimization applies, and any of the case values is not a
-     * literal int, we emit a series of `if..else` instead of a `js.Match`.
-     * This became necessary in 2.13.2 with strings and nulls.
      */
     def isInt(tree: js.Tree): Boolean = tree.tpe == jstpe.IntType
 
@@ -3217,32 +3257,8 @@ class JSCodeGen()(using genCtx: Context) {
         js.If(js.BinaryOp(op, genSelector, uniqueAlt), caseRhs, defaultClause)(resultType)
 
       case _ =>
-        if (isInt(genSelector) &&
-            clauses.forall(_._1.forall(_.isInstanceOf[js.IntLiteral]))) {
-          // We have int literals only: use a js.Match
-          val intClauses = clauses.asInstanceOf[List[(List[js.IntLiteral], js.Tree)]]
-          js.Match(genSelector, intClauses, defaultClause)(resultType)
-        } else {
-          // We have other stuff: generate an if..else chain
-          val (tempSelectorDef, tempSelectorRef) = genSelector match {
-            case varRef: js.VarRef =>
-              (js.Skip(), varRef)
-            case _ =>
-              val varDef = js.VarDef(freshLocalIdent(), NoOriginalName,
-                  genSelector.tpe, mutable = false, genSelector)
-              (varDef, varDef.ref)
-          }
-          val ifElseChain = clauses.foldRight(defaultClause) { (caze, elsep) =>
-            val conds = caze._1.map { caseValue =>
-              js.BinaryOp(js.BinaryOp.===, tempSelectorRef, caseValue)
-            }
-            val cond = conds.reduceRight[js.Tree] { (left, right) =>
-              js.If(left, js.BooleanLiteral(true), right)(jstpe.BooleanType)
-            }
-            js.If(cond, caze._2, elsep)(resultType)
-          }
-          js.Block(tempSelectorDef, ifElseChain)
-        }
+        // We have more than one case: use a js.Match
+        js.Match(genSelector, clauses, defaultClause)(resultType)
     }
   }
 
@@ -3511,7 +3527,7 @@ class JSCodeGen()(using genCtx: Context) {
   }
 
   /** Gen a statically linked call to an instance method. */
-  private def genApplyMethodMaybeStatically(receiver: js.Tree, method: Symbol,
+  def genApplyMethodMaybeStatically(receiver: js.Tree, method: Symbol,
       arguments: List[js.Tree])(implicit pos: Position): js.Tree = {
     if (method.isPrivate || method.isClassConstructor)
       genApplyMethodStatically(receiver, method, arguments)