diff --git a/compiler/testData/builtin-classes.txt b/compiler/testData/builtin-classes.txt
index ba12e7f348a..294e121a80e 100644
--- a/compiler/testData/builtin-classes.txt
+++ b/compiler/testData/builtin-classes.txt
@@ -476,98 +476,6 @@ public abstract class Enum</*0*/ E : kotlin.Enum<E>> : kotlin.Comparable<E> {
     }
 }
 
-public interface ExtensionFunction0</*0*/ in T, /*1*/ out R> {
-    public abstract fun T.invoke(): R
-}
-
-public interface ExtensionFunction1</*0*/ in T, /*1*/ in P1, /*2*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1): R
-}
-
-public interface ExtensionFunction10</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10): R
-}
-
-public interface ExtensionFunction11</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11): R
-}
-
-public interface ExtensionFunction12</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12): R
-}
-
-public interface ExtensionFunction13</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13): R
-}
-
-public interface ExtensionFunction14</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14): R
-}
-
-public interface ExtensionFunction15</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15): R
-}
-
-public interface ExtensionFunction16</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16): R
-}
-
-public interface ExtensionFunction17</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17): R
-}
-
-public interface ExtensionFunction18</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17, /*17*/ p18: P18): R
-}
-
-public interface ExtensionFunction19</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17, /*17*/ p18: P18, /*18*/ p19: P19): R
-}
-
-public interface ExtensionFunction2</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2): R
-}
-
-public interface ExtensionFunction20</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17, /*17*/ p18: P18, /*18*/ p19: P19, /*19*/ p20: P20): R
-}
-
-public interface ExtensionFunction21</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17, /*17*/ p18: P18, /*18*/ p19: P19, /*19*/ p20: P20, /*20*/ p21: P21): R
-}
-
-public interface ExtensionFunction22</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ in P22, /*23*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9, /*9*/ p10: P10, /*10*/ p11: P11, /*11*/ p12: P12, /*12*/ p13: P13, /*13*/ p14: P14, /*14*/ p15: P15, /*15*/ p16: P16, /*16*/ p17: P17, /*17*/ p18: P18, /*18*/ p19: P19, /*19*/ p20: P20, /*20*/ p21: P21, /*21*/ p22: P22): R
-}
-
-public interface ExtensionFunction3</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3): R
-}
-
-public interface ExtensionFunction4</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4): R
-}
-
-public interface ExtensionFunction5</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5): R
-}
-
-public interface ExtensionFunction6</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6): R
-}
-
-public interface ExtensionFunction7</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7): R
-}
-
-public interface ExtensionFunction8</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8): R
-}
-
-public interface ExtensionFunction9</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ out R> {
-    public abstract fun T.invoke(/*0*/ p1: P1, /*1*/ p2: P2, /*2*/ p3: P3, /*3*/ p4: P4, /*4*/ p5: P5, /*5*/ p6: P6, /*6*/ p7: P7, /*7*/ p8: P8, /*8*/ p9: P9): R
-}
-
 public final class Float : kotlin.Number, kotlin.Comparable<kotlin.Float> {
     /*primary*/ private constructor Float()
     public final fun compareTo(/*0*/ other: kotlin.Byte): kotlin.Int
diff --git a/core/builtins/src/kotlin/ExtensionFunctions.kt b/core/builtins/src/kotlin/ExtensionFunctions.kt
deleted file mode 100644
index 7621541f9e5..00000000000
--- a/core/builtins/src/kotlin/ExtensionFunctions.kt
+++ /dev/null
@@ -1,135 +0,0 @@
-/*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-// Auto-generated file. DO NOT EDIT!
-
-package kotlin
-
-/** An extension function that takes 0 arguments. */
-public interface ExtensionFunction0<in T, out R> : Function<R> {
-    /** Invokes the function. */
-    public fun T.invoke(): R
-}
-/** An extension function that takes 1 argument. */
-public interface ExtensionFunction1<in T, in P1, out R> : Function<R> {
-    /** Invokes the function with the specified argument. */
-    public fun T.invoke(p1: P1): R
-}
-/** An extension function that takes 2 arguments. */
-public interface ExtensionFunction2<in T, in P1, in P2, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2): R
-}
-/** An extension function that takes 3 arguments. */
-public interface ExtensionFunction3<in T, in P1, in P2, in P3, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3): R
-}
-/** An extension function that takes 4 arguments. */
-public interface ExtensionFunction4<in T, in P1, in P2, in P3, in P4, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4): R
-}
-/** An extension function that takes 5 arguments. */
-public interface ExtensionFunction5<in T, in P1, in P2, in P3, in P4, in P5, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5): R
-}
-/** An extension function that takes 6 arguments. */
-public interface ExtensionFunction6<in T, in P1, in P2, in P3, in P4, in P5, in P6, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6): R
-}
-/** An extension function that takes 7 arguments. */
-public interface ExtensionFunction7<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7): R
-}
-/** An extension function that takes 8 arguments. */
-public interface ExtensionFunction8<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8): R
-}
-/** An extension function that takes 9 arguments. */
-public interface ExtensionFunction9<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9): R
-}
-/** An extension function that takes 10 arguments. */
-public interface ExtensionFunction10<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10): R
-}
-/** An extension function that takes 11 arguments. */
-public interface ExtensionFunction11<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11): R
-}
-/** An extension function that takes 12 arguments. */
-public interface ExtensionFunction12<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12): R
-}
-/** An extension function that takes 13 arguments. */
-public interface ExtensionFunction13<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13): R
-}
-/** An extension function that takes 14 arguments. */
-public interface ExtensionFunction14<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14): R
-}
-/** An extension function that takes 15 arguments. */
-public interface ExtensionFunction15<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15): R
-}
-/** An extension function that takes 16 arguments. */
-public interface ExtensionFunction16<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16): R
-}
-/** An extension function that takes 17 arguments. */
-public interface ExtensionFunction17<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17): R
-}
-/** An extension function that takes 18 arguments. */
-public interface ExtensionFunction18<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18): R
-}
-/** An extension function that takes 19 arguments. */
-public interface ExtensionFunction19<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19): R
-}
-/** An extension function that takes 20 arguments. */
-public interface ExtensionFunction20<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20): R
-}
-/** An extension function that takes 21 arguments. */
-public interface ExtensionFunction21<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21): R
-}
-/** An extension function that takes 22 arguments. */
-public interface ExtensionFunction22<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, in P22, out R> : Function<R> {
-    /** Invokes the function with the specified arguments. */
-    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21, p22: P22): R
-}
diff --git a/generators/src/org/jetbrains/kotlin/generators/builtins/functions.kt b/generators/src/org/jetbrains/kotlin/generators/builtins/functions.kt
index 16bde8d463b..25c1625bfb6 100644
--- a/generators/src/org/jetbrains/kotlin/generators/builtins/functions.kt
+++ b/generators/src/org/jetbrains/kotlin/generators/builtins/functions.kt
@@ -21,30 +21,11 @@ import java.io.PrintWriter
 
 val MAX_PARAM_COUNT = 22
 
-enum class FunctionKind(
-        val classFqNamePrefix: String,
-        val docPrefix: String,
-        val hasReceiverParameter: Boolean
-) {
-    FUNCTION : FunctionKind("kotlin.jvm.functions.Function", "A function", false)
-    EXTENSION_FUNCTION : FunctionKind("kotlin.ExtensionFunction", "An extension function", true)
-
-    val classNamePrefix: String get() = classFqNamePrefix.substringAfterLast('.')
-    val packageFqName: String get() = classFqNamePrefix.substringBeforeLast('.')
-    val fileName: String get() = classFqNamePrefix.replace('.', '/') + "s.kt"
-
-    fun getClassName(i: Int) = classNamePrefix + i
-}
-
-class GenerateFunctions(out: PrintWriter, val kind: FunctionKind) : BuiltInsSourceGenerator(out) {
-    override fun getPackage() = kind.packageFqName
+class GenerateFunctions(out: PrintWriter) : BuiltInsSourceGenerator(out) {
+    override fun getPackage() = "kotlin.jvm.functions"
 
     fun generateTypeParameters(i: Int, variance: Boolean) {
         out.print("<")
-        if (kind.hasReceiverParameter) {
-            if (variance) out.print("in ")
-            out.print("T, ")
-        }
 
         for (j in 1..i) {
             if (variance) out.print("in ")
@@ -64,7 +45,7 @@ class GenerateFunctions(out: PrintWriter, val kind: FunctionKind) : BuiltInsSour
     override fun generateBody() {
         for (i in 0..MAX_PARAM_COUNT) {
             generateDocumentation(i)
-            out.print("public interface " + kind.getClassName(i))
+            out.print("public interface Function$i")
             generateTypeParameters(i, variance = true)
             generateSuperClass()
             generateFunctionClassBody(i)
@@ -73,7 +54,7 @@ class GenerateFunctions(out: PrintWriter, val kind: FunctionKind) : BuiltInsSour
 
     fun generateDocumentation(i: Int) {
         val suffix = if (i == 1) "" else "s"
-        out.println("/** ${kind.docPrefix} that takes $i argument${suffix}. */")
+        out.println("/** A function that takes $i argument${suffix}. */")
     }
 
     fun generateSuperClass() {
@@ -91,11 +72,12 @@ class GenerateFunctions(out: PrintWriter, val kind: FunctionKind) : BuiltInsSour
     fun generateInvokeSignature(i: Int) {
         if (i == 0) {
             out.println("    /** Invokes the function. */")
-        } else {
+        }
+        else {
             val suffix = if (i == 1) "" else "s"
             out.println("    /** Invokes the function with the specified argument${suffix}. */")
         }
-        out.print("    public fun ${if (kind.hasReceiverParameter) "T." else ""}invoke(")
+        out.print("    public fun invoke(")
         for (j in 1..i) {
             out.print("p$j: P$j")
             if (j < i) {
diff --git a/generators/src/org/jetbrains/kotlin/generators/builtins/generateBuiltIns.kt b/generators/src/org/jetbrains/kotlin/generators/builtins/generateBuiltIns.kt
index a001e133092..b34f6c8ad41 100644
--- a/generators/src/org/jetbrains/kotlin/generators/builtins/generateBuiltIns.kt
+++ b/generators/src/org/jetbrains/kotlin/generators/builtins/generateBuiltIns.kt
@@ -19,7 +19,6 @@ package org.jetbrains.kotlin.generators.builtins.generateBuiltIns
 import org.jetbrains.kotlin.generators.builtins.arrayIterators.GenerateArrayIterators
 import org.jetbrains.kotlin.generators.builtins.arrays.GenerateArrays
 import org.jetbrains.kotlin.generators.builtins.functionImpl.GenerateFunctionImpl
-import org.jetbrains.kotlin.generators.builtins.functions.FunctionKind
 import org.jetbrains.kotlin.generators.builtins.functions.GenerateFunctions
 import org.jetbrains.kotlin.generators.builtins.iterators.GenerateIterators
 import org.jetbrains.kotlin.generators.builtins.progressionIterators.GenerateProgressionIterators
@@ -67,11 +66,7 @@ fun generateBuiltIns(generate: (File, (PrintWriter) -> BuiltInsSourceGenerator)
     assertExists(BUILT_INS_SRC_DIR)
     assertExists(RUNTIME_JVM_DIR)
 
-    for (kind in FunctionKind.values()) {
-        val dir = if (kind == FunctionKind.FUNCTION) RUNTIME_JVM_DIR else BUILT_INS_SRC_DIR
-        generate(File(dir, kind.fileName)) { GenerateFunctions(it, kind) }
-    }
-
+    generate(File(RUNTIME_JVM_DIR, "kotlin/jvm/functions/Functions.kt")) { GenerateFunctions(it) }
     generate(File(RUNTIME_JVM_DIR, "kotlin/jvm/internal/FunctionImpl.java")) { GenerateFunctionImpl(it) }
     generate(File(BUILT_INS_NATIVE_DIR, "kotlin/Arrays.kt")) { GenerateArrays(it) }
     generate(File(BUILT_INS_NATIVE_DIR, "kotlin/Primitives.kt")) { GeneratePrimitives(it) }
diff --git a/jslib_files.xml b/jslib_files.xml
index ba89c65595f..6b228850dba 100644
--- a/jslib_files.xml
+++ b/jslib_files.xml
@@ -2,7 +2,6 @@
     <fileset id="kotlin.builtin.files" dir="${basedir}/core/builtins">
         <include name="native/kotlin/Iterator.kt"/>
         <include name="native/kotlin/Collections.kt"/>
-        <include name="src/kotlin/ExtensionFunctions.kt"/>
         <include name="src/kotlin/Function.kt"/>
         <include name="src/kotlin/Iterators.kt"/>
         <include name="src/kotlin/Range.kt"/>