Keep old version of MainProxies for scala#14156

compiler/src/dotty/tools/dotc/ast/MainProxies.scala

@@ -47,6 +47,96 @@ import Annotations.Annotation
   *     }
   */
 object MainProxies {
+  def mainProxiesOld(stats: List[tpd.Tree])(using Context): List[untpd.Tree] = {
+    import tpd._
+    def mainMethods(stats: List[Tree]): List[Symbol] = stats.flatMap {
+      case stat: DefDef if stat.symbol.hasAnnotation(defn.MainAnnot) =>
+        stat.symbol :: Nil
+      case stat @ TypeDef(name, impl: Template) if stat.symbol.is(Module) =>
+        mainMethods(impl.body)
+      case _ =>
+        Nil
+    }
+    mainMethods(stats).flatMap(mainProxyOld)
+  }
+
+  import untpd._
+  def mainProxyOld(mainFun: Symbol)(using Context): List[TypeDef] = {
+    val mainAnnotSpan = mainFun.getAnnotation(defn.MainAnnot).get.tree.span
+    def pos = mainFun.sourcePos
+    val argsRef = Ident(nme.args)
+
+    def addArgs(call: untpd.Tree, mt: MethodType, idx: Int): untpd.Tree =
+      if (mt.isImplicitMethod) {
+        report.error(s"@main method cannot have implicit parameters", pos)
+        call
+      }
+      else {
+        val args = mt.paramInfos.zipWithIndex map {
+          (formal, n) =>
+            val (parserSym, formalElem) =
+              if (formal.isRepeatedParam) (defn.CLP_parseRemainingArguments, formal.argTypes.head)
+              else (defn.CLP_parseArgument, formal)
+            val arg = Apply(
+              TypeApply(ref(parserSym.termRef), TypeTree(formalElem) :: Nil),
+              argsRef :: Literal(Constant(idx + n)) :: Nil)
+            if (formal.isRepeatedParam) repeated(arg) else arg
+        }
+        val call1 = Apply(call, args)
+        mt.resType match {
+          case restpe: MethodType =>
+            if (mt.paramInfos.lastOption.getOrElse(NoType).isRepeatedParam)
+              report.error(s"varargs parameter of @main method must come last", pos)
+            addArgs(call1, restpe, idx + args.length)
+          case _ =>
+            call1
+        }
+      }
+
+    var result: List[TypeDef] = Nil
+    if (!mainFun.owner.isStaticOwner)
+      report.error(s"@main method is not statically accessible", pos)
+    else {
+      var call = ref(mainFun.termRef)
+      mainFun.info match {
+        case _: ExprType =>
+        case mt: MethodType =>
+          call = addArgs(call, mt, 0)
+        case _: PolyType =>
+          report.error(s"@main method cannot have type parameters", pos)
+        case _ =>
+          report.error(s"@main can only annotate a method", pos)
+      }
+      val errVar = Ident(nme.error)
+      val handler = CaseDef(
+        Typed(errVar, TypeTree(defn.CLP_ParseError.typeRef)),
+        EmptyTree,
+        Apply(ref(defn.CLP_showError.termRef), errVar :: Nil))
+      val body = Try(call, handler :: Nil, EmptyTree)
+      val mainArg = ValDef(nme.args, TypeTree(defn.ArrayType.appliedTo(defn.StringType)), EmptyTree)
+        .withFlags(Param)
+      /** Replace typed `Ident`s that have been typed with a TypeSplice with the reference to the symbol.
+       *  The annotations will be retype-checked in another scope that may not have the same imports.
+       */
+      def insertTypeSplices = new TreeMap {
+          override def transform(tree: Tree)(using Context): Tree = tree match
+            case tree: tpd.Ident @unchecked => TypedSplice(tree)
+            case tree => super.transform(tree)
+      }
+      val annots = mainFun.annotations
+        .filterNot(_.matches(defn.MainAnnot))
+        .map(annot => insertTypeSplices.transform(annot.tree))
+      val mainMeth = DefDef(nme.main, (mainArg :: Nil) :: Nil, TypeTree(defn.UnitType), body)
+        .withFlags(JavaStatic)
+        .withAnnotations(annots)
+      val mainTempl = Template(emptyConstructor, Nil, Nil, EmptyValDef, mainMeth :: Nil)
+      val mainCls = TypeDef(mainFun.name.toTypeName, mainTempl)
+        .withFlags(Final | Invisible)
+      if (!ctx.reporter.hasErrors) result = mainCls.withSpan(mainAnnotSpan.toSynthetic) :: Nil
+    }
+    result
+  }
+
   private type DefaultValueSymbols = Map[Int, Symbol]
   private type ParameterAnnotationss = Seq[Seq[Annotation]]
 
@@ -95,7 +185,6 @@ object MainProxies {
     mainMethods(EmptyTree, stats).flatMap(mainProxy)
   }
 
-  import untpd._
   def mainProxy(mainFun: Symbol, paramAnnotations: ParameterAnnotationss, defaultValueSymbols: DefaultValueSymbols, docComment: Option[Comment])(using Context): List[TypeDef] = {
     val mainAnnot = mainFun.getAnnotation(defn.MainAnnot).get
     def pos = mainFun.sourcePos

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

@@ -871,6 +871,12 @@ class Definitions {
     @tu lazy val MainAnnotCommand_varargGetter: Symbol = MainAnnotCommand.requiredMethod("varargGetter")
     @tu lazy val MainAnnotCommand_run: Symbol = MainAnnotCommand.requiredMethod("run")
 
+  @tu lazy val CommandLineParserModule: Symbol = requiredModule("scala.util.CommandLineParser")
+    @tu lazy val CLP_ParseError: ClassSymbol = CommandLineParserModule.requiredClass("ParseError").typeRef.symbol.asClass
+    @tu lazy val CLP_parseArgument: Symbol = CommandLineParserModule.requiredMethod("parseArgument")
+    @tu lazy val CLP_parseRemainingArguments: Symbol = CommandLineParserModule.requiredMethod("parseRemainingArguments")
+    @tu lazy val CLP_showError: Symbol = CommandLineParserModule.requiredMethod("showError")
+
   @tu lazy val TupleTypeRef: TypeRef = requiredClassRef("scala.Tuple")
   def TupleClass(using Context): ClassSymbol = TupleTypeRef.symbol.asClass
     @tu lazy val Tuple_cons: Symbol = TupleClass.requiredMethod("*:")