diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/ArgumentTypeResolver.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/ArgumentTypeResolver.java
index 2328e564e6b..33e9c32da61 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/ArgumentTypeResolver.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/ArgumentTypeResolver.java
@@ -34,7 +34,7 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilKt;
 import org.jetbrains.kotlin.resolve.calls.context.CallResolutionContext;
 import org.jetbrains.kotlin.resolve.calls.context.CheckArgumentTypesMode;
 import org.jetbrains.kotlin.resolve.calls.context.ResolutionContext;
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImplKt;
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImplKt;
 import org.jetbrains.kotlin.resolve.calls.model.MutableDataFlowInfoForArguments;
 import org.jetbrains.kotlin.resolve.calls.results.OverloadResolutionResults;
 import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowInfo;
@@ -99,7 +99,7 @@ public class ArgumentTypeResolver {
             @NotNull KotlinType expectedType
     ) {
         if (FunctionPlaceholdersKt.isFunctionPlaceholder(actualType)) {
-            KotlinType functionType = ConstraintSystemImplKt.createTypeForFunctionPlaceholder(actualType, expectedType);
+            KotlinType functionType = ConstraintSystemBuilderImplKt.createTypeForFunctionPlaceholder(actualType, expectedType);
             return KotlinTypeChecker.DEFAULT.isSubtypeOf(functionType, expectedType);
         }
         return KotlinTypeChecker.DEFAULT.isSubtypeOf(actualType, expectedType);
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/GenericCandidateResolver.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/GenericCandidateResolver.kt
index 8f4023b000b..0bf65e94a05 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/GenericCandidateResolver.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/GenericCandidateResolver.kt
@@ -33,7 +33,7 @@ import org.jetbrains.kotlin.resolve.calls.context.ResolutionContext
 import org.jetbrains.kotlin.resolve.calls.context.ResolutionResultsCache
 import org.jetbrains.kotlin.resolve.calls.context.TemporaryTraceAndCache
 import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystem
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPosition
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind.RECEIVER_POSITION
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind.VALUE_PARAMETER_POSITION
@@ -53,7 +53,7 @@ class GenericCandidateResolver(private val argumentTypeResolver: ArgumentTypeRes
         val candidateCall = context.candidateCall
         val candidate = candidateCall.candidateDescriptor
 
-        val builder = ConstraintSystemImpl()
+        val builder = ConstraintSystemBuilderImpl()
 
         // If the call is recursive, e.g.
         //   fun foo<T>(t : T) : T = foo(t)
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilderImpl.kt
similarity index 99%
rename from compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt
rename to compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilderImpl.kt
index d806e83451e..16f505f84f2 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilderImpl.kt
@@ -20,8 +20,8 @@ import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.descriptors.annotations.FilteredAnnotations
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.EQUAL
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.SUB_TYPE
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.EQUAL
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.SUB_TYPE
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.Bound
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.BoundKind.*
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPosition
@@ -41,7 +41,7 @@ import org.jetbrains.kotlin.types.typeUtil.getNestedArguments
 import org.jetbrains.kotlin.types.typeUtil.isDefaultBound
 import java.util.*
 
-public class ConstraintSystemImpl : ConstraintSystem.Builder {
+public class ConstraintSystemBuilderImpl : ConstraintSystem.Builder {
 
     data class Constraint(val kind: ConstraintKind, val subtype: KotlinType, val superType: KotlinType, val position: ConstraintPosition)
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemSnapshot.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemSnapshot.kt
index 21c33a0200c..82988c0c4a7 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemSnapshot.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemSnapshot.kt
@@ -18,8 +18,8 @@ package org.jetbrains.kotlin.resolve.calls.inference
 
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.EQUAL
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.SUB_TYPE
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.EQUAL
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.SUB_TYPE
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPosition
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind.TYPE_BOUND_POSITION
@@ -38,7 +38,7 @@ class ConstraintSystemSnapshot(
         private val externalTypeParameters: Set<TypeParameterDescriptor>,
         private val usedInBounds: Map<TypeParameterDescriptor, MutableList<TypeBounds.Bound>>,
         private val errors: List<ConstraintError>,
-        private val initialConstraints: List<ConstraintSystemImpl.Constraint>,
+        private val initialConstraints: List<ConstraintSystemBuilderImpl.Constraint>,
         private val originalToVariables: Map<TypeParameterDescriptor, TypeParameterDescriptor>,
         private val variablesToOriginal: Map<TypeParameterDescriptor, TypeParameterDescriptor>
 ) : ConstraintSystem {
@@ -166,7 +166,7 @@ class ConstraintSystemSnapshot(
     }
 
     override fun toBuilder(filterConstraintPosition: (ConstraintPosition) -> Boolean): ConstraintSystem.Builder {
-        val result = ConstraintSystemImpl()
+        val result = ConstraintSystemBuilderImpl()
         for ((typeParameter, typeBounds) in allTypeParameterBounds) {
             result.allTypeParameterBounds.put(typeParameter, typeBounds.filter(filterConstraintPosition))
         }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/constraintIncorporation.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/constraintIncorporation.kt
index 39589af44cc..bbefa73a2b5 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/constraintIncorporation.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/constraintIncorporation.kt
@@ -17,8 +17,8 @@
 package org.jetbrains.kotlin.resolve.calls.inference
 
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.EQUAL
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl.ConstraintKind.SUB_TYPE
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.EQUAL
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.SUB_TYPE
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.Bound
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.BoundKind
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.BoundKind.*
@@ -39,7 +39,7 @@ data class ConstraintContext(
         val derivedFrom: Set<TypeParameterDescriptor>? = null,
         val initial: Boolean = false)
 
-fun ConstraintSystemImpl.incorporateBound(newBound: Bound) {
+fun ConstraintSystemBuilderImpl.incorporateBound(newBound: Bound) {
     val typeVariable = newBound.typeVariable
     val typeBounds = getTypeBounds(typeVariable)
 
@@ -67,7 +67,7 @@ fun ConstraintSystemImpl.incorporateBound(newBound: Bound) {
     }
 }
 
-private fun ConstraintSystemImpl.addConstraintFromBounds(old: Bound, new: Bound) {
+private fun ConstraintSystemBuilderImpl.addConstraintFromBounds(old: Bound, new: Bound) {
     if (old == new) return
 
     val oldType = old.constrainingType
@@ -81,7 +81,7 @@ private fun ConstraintSystemImpl.addConstraintFromBounds(old: Bound, new: Bound)
     }
 }
 
-private fun ConstraintSystemImpl.generateNewBound(bound: Bound, substitution: Bound) {
+private fun ConstraintSystemBuilderImpl.generateNewBound(bound: Bound, substitution: Bound) {
     // Let's have a bound 'T <=> My<R>', and a substitution 'R <=> Type'.
     // Here <=> means lower_bound, upper_bound or exact_bound constraint.
     // Then a new bound 'T <=> My<_/in/out Type>' can be generated.
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/TypeIntersector.java b/compiler/frontend/src/org/jetbrains/kotlin/types/TypeIntersector.java
index c8f6735e090..1c34030fcdc 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/TypeIntersector.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/TypeIntersector.java
@@ -26,7 +26,7 @@ import org.jetbrains.kotlin.descriptors.DeclarationDescriptor;
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor;
 import org.jetbrains.kotlin.descriptors.annotations.Annotations;
 import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystem;
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl;
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl;
 import org.jetbrains.kotlin.resolve.scopes.ChainedScope;
 import org.jetbrains.kotlin.resolve.scopes.MemberScope;
 import org.jetbrains.kotlin.types.checker.KotlinTypeChecker;
@@ -185,7 +185,7 @@ public class TypeIntersector {
             };
             processAllTypeParameters(withParameters, Variance.INVARIANT, processor);
             processAllTypeParameters(expected, Variance.INVARIANT, processor);
-            ConstraintSystem.Builder constraintSystem = new ConstraintSystemImpl();
+            ConstraintSystem.Builder constraintSystem = new ConstraintSystemBuilderImpl();
             constraintSystem.registerTypeVariables(parameters.keySet(), new Function1<TypeParameterDescriptor, TypeParameterDescriptor>() {
                 @Override
                 public TypeParameterDescriptor invoke(TypeParameterDescriptor descriptor) {
diff --git a/compiler/tests/org/jetbrains/kotlin/resolve/constraintSystem/AbstractConstraintSystemTest.kt b/compiler/tests/org/jetbrains/kotlin/resolve/constraintSystem/AbstractConstraintSystemTest.kt
index b0be726d0e9..ed4f8f2e8d9 100644
--- a/compiler/tests/org/jetbrains/kotlin/resolve/constraintSystem/AbstractConstraintSystemTest.kt
+++ b/compiler/tests/org/jetbrains/kotlin/resolve/constraintSystem/AbstractConstraintSystemTest.kt
@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.diagnostics.rendering.Renderers
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.resolve.TypeResolver
 import org.jetbrains.kotlin.resolve.calls.inference.ConstraintContext
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind.SPECIAL
 import org.jetbrains.kotlin.resolve.lazy.JvmResolveUtil
 import org.jetbrains.kotlin.test.ConfigurationKind
@@ -76,7 +76,7 @@ abstract public class AbstractConstraintSystemTest() : KotlinLiteFixture() {
         val constraintsFile = File(filePath)
         val constraintsFileText = constraintsFile.readLines()
 
-        val builder = ConstraintSystemImpl()
+        val builder = ConstraintSystemBuilderImpl()
 
         val variables = parseVariables(constraintsFileText)
         val fixVariables = constraintsFileText.contains("FIX_VARIABLES")
@@ -96,7 +96,7 @@ abstract public class AbstractConstraintSystemTest() : KotlinLiteFixture() {
                 MyConstraintKind.SUBTYPE -> builder.addSubtypeConstraint(firstType, secondType, context.position)
                 MyConstraintKind.SUPERTYPE -> builder.addSupertypeConstraint(firstType, secondType, context.position)
                 MyConstraintKind.EQUAL -> builder.addConstraint(
-                        ConstraintSystemImpl.ConstraintKind.EQUAL, firstType, secondType, context)
+                        ConstraintSystemBuilderImpl.ConstraintKind.EQUAL, firstType, secondType, context)
             }
         }
 
diff --git a/idea/ide-common/src/org/jetbrains/kotlin/idea/util/FuzzyType.kt b/idea/ide-common/src/org/jetbrains/kotlin/idea/util/FuzzyType.kt
index c379b2e2860..2934764c7a5 100644
--- a/idea/ide-common/src/org/jetbrains/kotlin/idea/util/FuzzyType.kt
+++ b/idea/ide-common/src/org/jetbrains/kotlin/idea/util/FuzzyType.kt
@@ -20,7 +20,7 @@ package org.jetbrains.kotlin.idea.util
 
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
-import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemImpl
+import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl
 import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeSubstitutor
@@ -116,7 +116,7 @@ class FuzzyType(
             return if (type.checkInheritance(otherType.type)) TypeSubstitutor.EMPTY else null
         }
 
-        val builder = ConstraintSystemImpl()
+        val builder = ConstraintSystemBuilderImpl()
         builder.registerTypeVariables(freeParameters)
         builder.registerTypeVariables(otherType.freeParameters)