diff --git a/build-common/test/org/jetbrains/kotlin/metadata/DebugProtoBuf.java b/build-common/test/org/jetbrains/kotlin/metadata/DebugProtoBuf.java
index a2b354548fe..946e948e2db 100644
--- a/build-common/test/org/jetbrains/kotlin/metadata/DebugProtoBuf.java
+++ b/build-common/test/org/jetbrains/kotlin/metadata/DebugProtoBuf.java
@@ -17258,6 +17258,7 @@ public final class DebugProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     boolean hasFlags();
@@ -17268,6 +17269,7 @@ public final class DebugProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     int getFlags();
@@ -17463,6 +17465,7 @@ public final class DebugProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     public boolean hasFlags() {
@@ -17475,6 +17478,7 @@ public final class DebugProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     public int getFlags() {
@@ -17894,6 +17898,7 @@ public final class DebugProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public boolean hasFlags() {
@@ -17906,6 +17911,7 @@ public final class DebugProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public int getFlags() {
@@ -17918,6 +17924,7 @@ public final class DebugProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder setFlags(int value) {
@@ -17933,6 +17940,7 @@ public final class DebugProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder clearFlags() {
@@ -18307,6 +18315,7 @@ public final class DebugProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     boolean hasFlags();
@@ -18325,6 +18334,7 @@ public final class DebugProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     int getFlags();
@@ -18723,6 +18733,7 @@ public final class DebugProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     public boolean hasFlags() {
@@ -18743,6 +18754,7 @@ public final class DebugProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     public int getFlags() {
@@ -19639,6 +19651,7 @@ public final class DebugProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public boolean hasFlags() {
@@ -19659,6 +19672,7 @@ public final class DebugProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public int getFlags() {
@@ -19679,6 +19693,7 @@ public final class DebugProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder setFlags(int value) {
@@ -19702,6 +19717,7 @@ public final class DebugProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder clearFlags() {
diff --git a/build-common/test/org/jetbrains/kotlin/metadata/jvm/DebugJvmProtoBuf.java b/build-common/test/org/jetbrains/kotlin/metadata/jvm/DebugJvmProtoBuf.java
index f164b522955..e236c70e974 100644
--- a/build-common/test/org/jetbrains/kotlin/metadata/jvm/DebugJvmProtoBuf.java
+++ b/build-common/test/org/jetbrains/kotlin/metadata/jvm/DebugJvmProtoBuf.java
@@ -4656,7 +4656,8 @@ public final class DebugJvmProtoBuf {
    * <code>extend .org.jetbrains.kotlin.metadata.Class { ... }</code>
    *
    * <pre>
-   * isFunctionBodyInInterface: 0 if actual body generated in DefaultImpl, 1 - otherwise (in interface default method)
+   * first bit: isFunctionBodyInInterface: 0 if actual body generated in DefaultImpl, 1 - otherwise (in interface default method)
+   * second bit: is all-compatibility mode or not, 1 - yes, 0 - no
    * </pre>
    */
   public static final
diff --git a/compiler/ir/serialization.common/src/KotlinIr.proto b/compiler/ir/serialization.common/src/KotlinIr.proto
index 3bc94fc6e6e..a3d4c504468 100644
--- a/compiler/ir/serialization.common/src/KotlinIr.proto
+++ b/compiler/ir/serialization.common/src/KotlinIr.proto
@@ -246,7 +246,7 @@ message IrSetField {
   optional int32 origin_name = 3;
 }
 
-message IrSetVariable {
+message IrSetValue {
   required int64 symbol = 1;
   required IrExpression value = 2;
   optional int32 origin_name = 3;
@@ -375,7 +375,7 @@ message IrOperation {
     IrPropertyReference property_reference = 18;
     IrReturn return = 19;
     IrSetField set_field = 20;
-    IrSetVariable set_variable = 21;
+    IrSetValue set_value = 21;
     IrStringConcat string_concat = 22;
     IrThrow throw = 23;
     IrTry try = 24;
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
index 63cdc14bb36..c663e12ffeb 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
@@ -80,7 +80,7 @@ import org.jetbrains.kotlin.backend.common.serialization.proto.IrProperty as Pro
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrPropertyReference as ProtoPropertyReference
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrReturn as ProtoReturn
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetField as ProtoSetField
-import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable as ProtoSetVariable
+import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue as ProtoSetValue
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSimpleType as ProtoSimpleType
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSpreadElement as ProtoSpreadElement
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrStatement as ProtoStatement
@@ -607,7 +607,7 @@ abstract class IrFileDeserializer(
         return IrSetFieldImpl(start, end, symbol, receiver, value, builtIns.unitType, origin, superQualifier)
     }
 
-    private fun deserializeSetVariable(proto: ProtoSetVariable, start: Int, end: Int): IrSetValue {
+    private fun deserializeSetValue(proto: ProtoSetValue, start: Int, end: Int): IrSetValue {
         val symbol = deserializeIrSymbolAndRemap(proto.symbol) as IrVariableSymbol
         val value = deserializeExpression(proto.value)
         val origin = if (proto.hasOriginName()) deserializeIrStatementOrigin(proto.originName) else null
@@ -879,7 +879,7 @@ abstract class IrFileDeserializer(
             PROPERTY_REFERENCE -> deserializePropertyReference(proto.propertyReference, start, end, type)
             RETURN -> deserializeReturn(proto.`return`, start, end)
             SET_FIELD -> deserializeSetField(proto.setField, start, end)
-            SET_VARIABLE -> deserializeSetVariable(proto.setVariable, start, end)
+            SET_VALUE -> deserializeSetValue(proto.setValue, start, end)
             STRING_CONCAT -> deserializeStringConcat(proto.stringConcat, start, end, type)
             THROW -> deserializeThrow(proto.`throw`, start, end)
             TRY -> deserializeTry(proto.`try`, start, end, type)
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
index 3933a30f2b9..ac15e29bfe9 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
@@ -74,7 +74,7 @@ import org.jetbrains.kotlin.backend.common.serialization.proto.IrProperty as Pro
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrPropertyReference as ProtoPropertyReference
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrReturn as ProtoReturn
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetField as ProtoSetField
-import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable as ProtoSetVariable
+import org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue as ProtoSetValue
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSimpleType as ProtoSimpleType
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrSpreadElement as ProtoSpreadElement
 import org.jetbrains.kotlin.backend.common.serialization.proto.IrStatement as ProtoStatement
@@ -673,8 +673,8 @@ open class IrFileSerializer(
             }
             .build()
 
-    private fun serializeSetVariable(expression: IrSetValue): ProtoSetVariable =
-        ProtoSetVariable.newBuilder()
+    private fun serializeSetValue(expression: IrSetValue): ProtoSetValue =
+        ProtoSetValue.newBuilder()
             .setSymbol(serializeIrSymbol(expression.symbol))
             .setValue(serializeExpression(expression.value)).apply {
                 expression.origin?.let { originName = serializeIrStatementOrigin(it) }
@@ -933,7 +933,7 @@ open class IrFileSerializer(
             is IrPropertyReference -> operationProto.propertyReference = serializePropertyReference(expression)
             is IrReturn -> operationProto.`return` = serializeReturn(expression)
             is IrSetField -> operationProto.setField = serializeSetField(expression)
-            is IrSetValue -> operationProto.setVariable = serializeSetVariable(expression)
+            is IrSetValue -> operationProto.setValue = serializeSetValue(expression)
             is IrStringConcatenation -> operationProto.stringConcat = serializeStringConcat(expression)
             is IrThrow -> operationProto.`throw` = serializeThrow(expression)
             is IrTry -> operationProto.`try` = serializeTry(expression)
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperation.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperation.java
index 84127ece1e7..8db13f55738 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperation.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperation.java
@@ -320,13 +320,13 @@ public final class IrOperation extends
             break;
           }
           case 170: {
-            org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.Builder subBuilder = null;
+            org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.Builder subBuilder = null;
             if (operationCase_ == 21) {
-              subBuilder = ((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_).toBuilder();
+              subBuilder = ((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_).toBuilder();
             }
-            operation_ = input.readMessage(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.PARSER, extensionRegistry);
+            operation_ = input.readMessage(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.PARSER, extensionRegistry);
             if (subBuilder != null) {
-              subBuilder.mergeFrom((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_);
+              subBuilder.mergeFrom((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_);
               operation_ = subBuilder.buildPartial();
             }
             operationCase_ = 21;
@@ -547,7 +547,7 @@ public final class IrOperation extends
     PROPERTY_REFERENCE(18),
     RETURN(19),
     SET_FIELD(20),
-    SET_VARIABLE(21),
+    SET_VALUE(21),
     STRING_CONCAT(22),
     THROW(23),
     TRY(24),
@@ -587,7 +587,7 @@ public final class IrOperation extends
         case 18: return PROPERTY_REFERENCE;
         case 19: return RETURN;
         case 20: return SET_FIELD;
-        case 21: return SET_VARIABLE;
+        case 21: return SET_VALUE;
         case 22: return STRING_CONCAT;
         case 23: return THROW;
         case 24: return TRY;
@@ -956,21 +956,21 @@ public final class IrOperation extends
     return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetField.getDefaultInstance();
   }
 
-  public static final int SET_VARIABLE_FIELD_NUMBER = 21;
+  public static final int SET_VALUE_FIELD_NUMBER = 21;
   /**
-   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
    */
-  public boolean hasSetVariable() {
+  public boolean hasSetValue() {
     return operationCase_ == 21;
   }
   /**
-   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
    */
-  public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable getSetVariable() {
+  public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue getSetValue() {
     if (operationCase_ == 21) {
-       return (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_;
+       return (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_;
     }
-    return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.getDefaultInstance();
+    return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.getDefaultInstance();
   }
 
   public static final int STRING_CONCAT_FIELD_NUMBER = 22;
@@ -1299,8 +1299,8 @@ public final class IrOperation extends
         return false;
       }
     }
-    if (hasSetVariable()) {
-      if (!getSetVariable().isInitialized()) {
+    if (hasSetValue()) {
+      if (!getSetValue().isInitialized()) {
         memoizedIsInitialized = 0;
         return false;
       }
@@ -1445,7 +1445,7 @@ public final class IrOperation extends
       output.writeMessage(20, (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetField) operation_);
     }
     if (operationCase_ == 21) {
-      output.writeMessage(21, (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_);
+      output.writeMessage(21, (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_);
     }
     if (operationCase_ == 22) {
       output.writeMessage(22, (org.jetbrains.kotlin.backend.common.serialization.proto.IrStringConcat) operation_);
@@ -1574,7 +1574,7 @@ public final class IrOperation extends
     }
     if (operationCase_ == 21) {
       size += org.jetbrains.kotlin.protobuf.CodedOutputStream
-        .computeMessageSize(21, (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_);
+        .computeMessageSize(21, (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_);
     }
     if (operationCase_ == 22) {
       size += org.jetbrains.kotlin.protobuf.CodedOutputStream
@@ -1938,8 +1938,8 @@ public final class IrOperation extends
           mergeSetField(other.getSetField());
           break;
         }
-        case SET_VARIABLE: {
-          mergeSetVariable(other.getSetVariable());
+        case SET_VALUE: {
+          mergeSetValue(other.getSetValue());
           break;
         }
         case STRING_CONCAT: {
@@ -2114,8 +2114,8 @@ public final class IrOperation extends
           return false;
         }
       }
-      if (hasSetVariable()) {
-        if (!getSetVariable().isInitialized()) {
+      if (hasSetValue()) {
+        if (!getSetValue().isInitialized()) {
           
           return false;
         }
@@ -3510,24 +3510,24 @@ public final class IrOperation extends
     }
 
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public boolean hasSetVariable() {
+    public boolean hasSetValue() {
       return operationCase_ == 21;
     }
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable getSetVariable() {
+    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue getSetValue() {
       if (operationCase_ == 21) {
-        return (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_;
+        return (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_;
       }
-      return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.getDefaultInstance();
+      return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.getDefaultInstance();
     }
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public Builder setSetVariable(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable value) {
+    public Builder setSetValue(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue value) {
       if (value == null) {
         throw new NullPointerException();
       }
@@ -3537,22 +3537,22 @@ public final class IrOperation extends
       return this;
     }
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public Builder setSetVariable(
-        org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.Builder builderForValue) {
+    public Builder setSetValue(
+        org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.Builder builderForValue) {
       operation_ = builderForValue.build();
 
       operationCase_ = 21;
       return this;
     }
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public Builder mergeSetVariable(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable value) {
+    public Builder mergeSetValue(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue value) {
       if (operationCase_ == 21 &&
-          operation_ != org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.getDefaultInstance()) {
-        operation_ = org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.newBuilder((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) operation_)
+          operation_ != org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.getDefaultInstance()) {
+        operation_ = org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.newBuilder((org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) operation_)
             .mergeFrom(value).buildPartial();
       } else {
         operation_ = value;
@@ -3562,9 +3562,9 @@ public final class IrOperation extends
       return this;
     }
     /**
-     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+     * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
      */
-    public Builder clearSetVariable() {
+    public Builder clearSetValue() {
       if (operationCase_ == 21) {
         operationCase_ = 0;
         operation_ = null;
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperationOrBuilder.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperationOrBuilder.java
index 052e8ac26af..fdf0d84d383 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperationOrBuilder.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperationOrBuilder.java
@@ -188,13 +188,13 @@ public interface IrOperationOrBuilder extends
   org.jetbrains.kotlin.backend.common.serialization.proto.IrSetField getSetField();
 
   /**
-   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
    */
-  boolean hasSetVariable();
+  boolean hasSetValue();
   /**
-   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable set_variable = 21;</code>
+   * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue set_value = 21;</code>
    */
-  org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable getSetVariable();
+  org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue getSetValue();
 
   /**
    * <code>optional .org.jetbrains.kotlin.backend.common.serialization.proto.IrStringConcat string_concat = 22;</code>
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariable.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValue.java
similarity index 88%
rename from compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariable.java
rename to compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValue.java
index 4ea0b3b3cad..4c60e339155 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariable.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValue.java
@@ -4,30 +4,30 @@
 package org.jetbrains.kotlin.backend.common.serialization.proto;
 
 /**
- * Protobuf type {@code org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable}
+ * Protobuf type {@code org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue}
  */
-public final class IrSetVariable extends
+public final class IrSetValue extends
     org.jetbrains.kotlin.protobuf.GeneratedMessageLite implements
-    // @@protoc_insertion_point(message_implements:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable)
-    IrSetVariableOrBuilder {
-  // Use IrSetVariable.newBuilder() to construct.
-  private IrSetVariable(org.jetbrains.kotlin.protobuf.GeneratedMessageLite.Builder builder) {
+    // @@protoc_insertion_point(message_implements:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue)
+    IrSetValueOrBuilder {
+  // Use IrSetValue.newBuilder() to construct.
+  private IrSetValue(org.jetbrains.kotlin.protobuf.GeneratedMessageLite.Builder builder) {
     super(builder);
     this.unknownFields = builder.getUnknownFields();
   }
-  private IrSetVariable(boolean noInit) { this.unknownFields = org.jetbrains.kotlin.protobuf.ByteString.EMPTY;}
+  private IrSetValue(boolean noInit) { this.unknownFields = org.jetbrains.kotlin.protobuf.ByteString.EMPTY;}
 
-  private static final IrSetVariable defaultInstance;
-  public static IrSetVariable getDefaultInstance() {
+  private static final IrSetValue defaultInstance;
+  public static IrSetValue getDefaultInstance() {
     return defaultInstance;
   }
 
-  public IrSetVariable getDefaultInstanceForType() {
+  public IrSetValue getDefaultInstanceForType() {
     return defaultInstance;
   }
 
   private final org.jetbrains.kotlin.protobuf.ByteString unknownFields;
-  private IrSetVariable(
+  private IrSetValue(
       org.jetbrains.kotlin.protobuf.CodedInputStream input,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
@@ -94,18 +94,18 @@ public final class IrSetVariable extends
       makeExtensionsImmutable();
     }
   }
-  public static org.jetbrains.kotlin.protobuf.Parser<IrSetVariable> PARSER =
-      new org.jetbrains.kotlin.protobuf.AbstractParser<IrSetVariable>() {
-    public IrSetVariable parsePartialFrom(
+  public static org.jetbrains.kotlin.protobuf.Parser<IrSetValue> PARSER =
+      new org.jetbrains.kotlin.protobuf.AbstractParser<IrSetValue>() {
+    public IrSetValue parsePartialFrom(
         org.jetbrains.kotlin.protobuf.CodedInputStream input,
         org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
         throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
-      return new IrSetVariable(input, extensionRegistry);
+      return new IrSetValue(input, extensionRegistry);
     }
   };
 
   @java.lang.Override
-  public org.jetbrains.kotlin.protobuf.Parser<IrSetVariable> getParserForType() {
+  public org.jetbrains.kotlin.protobuf.Parser<IrSetValue> getParserForType() {
     return PARSER;
   }
 
@@ -227,53 +227,53 @@ public final class IrSetVariable extends
     return super.writeReplace();
   }
 
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       org.jetbrains.kotlin.protobuf.ByteString data)
       throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
     return PARSER.parseFrom(data);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       org.jetbrains.kotlin.protobuf.ByteString data,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
     return PARSER.parseFrom(data, extensionRegistry);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(byte[] data)
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(byte[] data)
       throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
     return PARSER.parseFrom(data);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       byte[] data,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException {
     return PARSER.parseFrom(data, extensionRegistry);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(java.io.InputStream input)
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(java.io.InputStream input)
       throws java.io.IOException {
     return PARSER.parseFrom(input);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       java.io.InputStream input,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws java.io.IOException {
     return PARSER.parseFrom(input, extensionRegistry);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseDelimitedFrom(java.io.InputStream input)
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseDelimitedFrom(java.io.InputStream input)
       throws java.io.IOException {
     return PARSER.parseDelimitedFrom(input);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseDelimitedFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseDelimitedFrom(
       java.io.InputStream input,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws java.io.IOException {
     return PARSER.parseDelimitedFrom(input, extensionRegistry);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       org.jetbrains.kotlin.protobuf.CodedInputStream input)
       throws java.io.IOException {
     return PARSER.parseFrom(input);
   }
-  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parseFrom(
+  public static org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parseFrom(
       org.jetbrains.kotlin.protobuf.CodedInputStream input,
       org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
       throws java.io.IOException {
@@ -282,21 +282,21 @@ public final class IrSetVariable extends
 
   public static Builder newBuilder() { return Builder.create(); }
   public Builder newBuilderForType() { return newBuilder(); }
-  public static Builder newBuilder(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable prototype) {
+  public static Builder newBuilder(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue prototype) {
     return newBuilder().mergeFrom(prototype);
   }
   public Builder toBuilder() { return newBuilder(this); }
 
   /**
-   * Protobuf type {@code org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable}
+   * Protobuf type {@code org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue}
    */
   public static final class Builder extends
       org.jetbrains.kotlin.protobuf.GeneratedMessageLite.Builder<
-        org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable, Builder>
+        org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue, Builder>
       implements
-      // @@protoc_insertion_point(builder_implements:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable)
-      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariableOrBuilder {
-    // Construct using org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.newBuilder()
+      // @@protoc_insertion_point(builder_implements:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue)
+      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValueOrBuilder {
+    // Construct using org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.newBuilder()
     private Builder() {
       maybeForceBuilderInitialization();
     }
@@ -322,20 +322,20 @@ public final class IrSetVariable extends
       return create().mergeFrom(buildPartial());
     }
 
-    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable getDefaultInstanceForType() {
-      return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.getDefaultInstance();
+    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue getDefaultInstanceForType() {
+      return org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.getDefaultInstance();
     }
 
-    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable build() {
-      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable result = buildPartial();
+    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue build() {
+      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue result = buildPartial();
       if (!result.isInitialized()) {
         throw newUninitializedMessageException(result);
       }
       return result;
     }
 
-    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable buildPartial() {
-      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable result = new org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable(this);
+    public org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue buildPartial() {
+      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue result = new org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue(this);
       int from_bitField0_ = bitField0_;
       int to_bitField0_ = 0;
       if (((from_bitField0_ & 0x00000001) == 0x00000001)) {
@@ -354,8 +354,8 @@ public final class IrSetVariable extends
       return result;
     }
 
-    public Builder mergeFrom(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable other) {
-      if (other == org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable.getDefaultInstance()) return this;
+    public Builder mergeFrom(org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue other) {
+      if (other == org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue.getDefaultInstance()) return this;
       if (other.hasSymbol()) {
         setSymbol(other.getSymbol());
       }
@@ -390,11 +390,11 @@ public final class IrSetVariable extends
         org.jetbrains.kotlin.protobuf.CodedInputStream input,
         org.jetbrains.kotlin.protobuf.ExtensionRegistryLite extensionRegistry)
         throws java.io.IOException {
-      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable parsedMessage = null;
+      org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue parsedMessage = null;
       try {
         parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
       } catch (org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException e) {
-        parsedMessage = (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable) e.getUnfinishedMessage();
+        parsedMessage = (org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue) e.getUnfinishedMessage();
         throw e;
       } finally {
         if (parsedMessage != null) {
@@ -529,13 +529,13 @@ public final class IrSetVariable extends
       return this;
     }
 
-    // @@protoc_insertion_point(builder_scope:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable)
+    // @@protoc_insertion_point(builder_scope:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue)
   }
 
   static {
-    defaultInstance = new IrSetVariable(true);
+    defaultInstance = new IrSetValue(true);
     defaultInstance.initFields();
   }
 
-  // @@protoc_insertion_point(class_scope:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable)
+  // @@protoc_insertion_point(class_scope:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue)
 }
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariableOrBuilder.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValueOrBuilder.java
similarity index 90%
rename from compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariableOrBuilder.java
rename to compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValueOrBuilder.java
index 766b4a4bf05..0f0310b4dc9 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetVariableOrBuilder.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrSetValueOrBuilder.java
@@ -3,8 +3,8 @@
 
 package org.jetbrains.kotlin.backend.common.serialization.proto;
 
-public interface IrSetVariableOrBuilder extends
-    // @@protoc_insertion_point(interface_extends:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetVariable)
+public interface IrSetValueOrBuilder extends
+    // @@protoc_insertion_point(interface_extends:org.jetbrains.kotlin.backend.common.serialization.proto.IrSetValue)
     org.jetbrains.kotlin.protobuf.MessageLiteOrBuilder {
 
   /**
diff --git a/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/JvmProtoBuf.java b/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/JvmProtoBuf.java
index 37e016c4752..f698aa3764d 100644
--- a/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/JvmProtoBuf.java
+++ b/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/JvmProtoBuf.java
@@ -3991,7 +3991,8 @@ public final class JvmProtoBuf {
    * <code>extend .org.jetbrains.kotlin.metadata.Class { ... }</code>
    *
    * <pre>
-   * isFunctionBodyInInterface: 0 if actual body generated in DefaultImpl, 1 - otherwise (in interface default method)
+   * first bit: isFunctionBodyInInterface: 0 if actual body generated in DefaultImpl, 1 - otherwise (in interface default method)
+   * second bit: is all-compatibility mode or not, 1 - yes, 0 - no
    * </pre>
    */
   public static final
diff --git a/core/metadata/src/org/jetbrains/kotlin/metadata/ProtoBuf.java b/core/metadata/src/org/jetbrains/kotlin/metadata/ProtoBuf.java
index 3847b3915e2..e4ab28fc0eb 100644
--- a/core/metadata/src/org/jetbrains/kotlin/metadata/ProtoBuf.java
+++ b/core/metadata/src/org/jetbrains/kotlin/metadata/ProtoBuf.java
@@ -13316,6 +13316,7 @@ public final class ProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     boolean hasFlags();
@@ -13326,6 +13327,7 @@ public final class ProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     int getFlags();
@@ -13503,6 +13505,7 @@ public final class ProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     public boolean hasFlags() {
@@ -13515,6 +13518,7 @@ public final class ProtoBuf {
      *hasAnnotations
      *Visibility
      *isSecondary
+     *hasNonStableParameterNames
      * </pre>
      */
     public int getFlags() {
@@ -13870,6 +13874,7 @@ public final class ProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public boolean hasFlags() {
@@ -13882,6 +13887,7 @@ public final class ProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public int getFlags() {
@@ -13894,6 +13900,7 @@ public final class ProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder setFlags(int value) {
@@ -13909,6 +13916,7 @@ public final class ProtoBuf {
        *hasAnnotations
        *Visibility
        *isSecondary
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder clearFlags() {
@@ -14168,6 +14176,7 @@ public final class ProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     boolean hasFlags();
@@ -14186,6 +14195,7 @@ public final class ProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     int getFlags();
@@ -14540,6 +14550,7 @@ public final class ProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     public boolean hasFlags() {
@@ -14560,6 +14571,7 @@ public final class ProtoBuf {
      *isExternal
      *isSuspend
      *isExpect
+     *hasNonStableParameterNames
      * </pre>
      */
     public int getFlags() {
@@ -15307,6 +15319,7 @@ public final class ProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public boolean hasFlags() {
@@ -15327,6 +15340,7 @@ public final class ProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public int getFlags() {
@@ -15347,6 +15361,7 @@ public final class ProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder setFlags(int value) {
@@ -15370,6 +15385,7 @@ public final class ProtoBuf {
        *isExternal
        *isSuspend
        *isExpect
+       *hasNonStableParameterNames
        * </pre>
        */
       public Builder clearFlags() {
diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/extensions/SerializationPluginMetadataExtensions.java b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/extensions/SerializationPluginMetadataExtensions.java
index 17ba5efe5bf..07ffd939d62 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/extensions/SerializationPluginMetadataExtensions.java
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/extensions/SerializationPluginMetadataExtensions.java
@@ -1,43 +1,33 @@
-/*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
 // Generated by the protocol buffer compiler.  DO NOT EDIT!
 // source: plugins/kotlin-serialization/kotlin-serialization-compiler/src/class_extensions.proto
 
 package org.jetbrains.kotlinx.serialization.compiler.extensions;
 
 public final class SerializationPluginMetadataExtensions {
-    private SerializationPluginMetadataExtensions() {
-    }
-
-    public static void registerAllExtensions(
-            org.jetbrains.kotlin.protobuf.ExtensionRegistryLite registry
-    ) {
-        registry.add(
-                org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationPluginMetadataExtensions.propertiesNamesInProgramOrder);
-    }
-
-    public static final int PROPERTIES_NAMES_IN_PROGRAM_ORDER_FIELD_NUMBER = 18000;
-    /**
-     * <code>extend .org.jetbrains.kotlin.metadata.Class { ... }</code>
-     */
-    public static final
+  private SerializationPluginMetadataExtensions() {}
+  public static void registerAllExtensions(
+      org.jetbrains.kotlin.protobuf.ExtensionRegistryLite registry) {
+    registry.add(org.jetbrains.kotlinx.serialization.compiler.extensions.SerializationPluginMetadataExtensions.propertiesNamesInProgramOrder);
+  }
+  public static final int PROPERTIES_NAMES_IN_PROGRAM_ORDER_FIELD_NUMBER = 18000;
+  /**
+   * <code>extend .org.jetbrains.kotlin.metadata.Class { ... }</code>
+   */
+  public static final
     org.jetbrains.kotlin.protobuf.GeneratedMessageLite.GeneratedExtension<
-            org.jetbrains.kotlin.metadata.ProtoBuf.Class,
-            java.util.List<java.lang.Integer>> propertiesNamesInProgramOrder = org.jetbrains.kotlin.protobuf.GeneratedMessageLite
-            .newRepeatedGeneratedExtension(
-                    org.jetbrains.kotlin.metadata.ProtoBuf.Class.getDefaultInstance(),
-                    null,
-                    null,
-                    18000,
-                    org.jetbrains.kotlin.protobuf.WireFormat.FieldType.INT32,
-                    false,
-                    java.lang.Integer.class);
+      org.jetbrains.kotlin.metadata.ProtoBuf.Class,
+      java.util.List<java.lang.Integer>> propertiesNamesInProgramOrder = org.jetbrains.kotlin.protobuf.GeneratedMessageLite
+          .newRepeatedGeneratedExtension(
+        org.jetbrains.kotlin.metadata.ProtoBuf.Class.getDefaultInstance(),
+        null,
+        null,
+        18000,
+        org.jetbrains.kotlin.protobuf.WireFormat.FieldType.INT32,
+        false,
+        java.lang.Integer.class);
 
-    static {
-    }
+  static {
+  }
 
-    // @@protoc_insertion_point(outer_class_scope)
+  // @@protoc_insertion_point(outer_class_scope)
 }
\ No newline at end of file