Merge pull request #6111 from dotty-staging/fix-6109

Fix #6109: implement FunctionX.curried

Author: smarter

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -1176,9 +1176,9 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
       else {
         val arity = field.meth.tpe.widenDealias.paramTypes.size - _1.size
         val returnsUnit = field.meth.tpe.widenDealias.resultType.classSymbol == UnitClass
-        if (returnsUnit)
-          ctx.requiredClass(("dotty.runtime.function.JProcedure" + arity))
-        else ctx.requiredClass(("dotty.runtime.function.JFunction" + arity))
+        if (returnsUnit) ctx.requiredClass(("dotty.runtime.function.JProcedure" + arity))
+        else if (arity <= 2) ctx.requiredClass(("dotty.runtime.function.JFunction" + arity))
+        else ctx.requiredClass(("scala.Function" + arity))
       }
     }
   }

library/src/dotty/runtime/function/JFunction.java

@@ -7,8 +7,6 @@
 
 @FunctionalInterface
 public interface JFunction0<R> extends scala.Function0<R>, java.io.Serializable {
-    default void $init$() {
-    };
     default void apply$mcV$sp() {
         apply();
     }

library/src/dotty/runtime/function/JFunction0.java

@@ -7,8 +7,6 @@
 
 @FunctionalInterface
 public interface JFunction1<T1, R> extends scala.Function1<T1, R>, java.io.Serializable {
-    default void $init$() {
-    };
 
     @Override
     @SuppressWarnings("unchecked")
@@ -213,7 +211,7 @@ default <A> scala.Function1<A, R> compose(scala.Function1<A, T1> g) {
     default scala.Function1 compose$mcDD$sp(scala.Function1 g) {
         return compose(g);
     }
-    
+
     @SuppressWarnings("unchecked")
     default scala.Function1 andThen$mcVI$sp(scala.Function1 g) {
         return andThen(g);