Approximate captured types only when necessary

core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt

@@ -42,6 +42,7 @@ import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.CompoundC
 import org.jetbrains.kotlin.types.getCustomTypeVariable
 import org.jetbrains.kotlin.types.isFlexible
 import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.Bound
+import org.jetbrains.kotlin.types.TypeSubstitution
 
 public class ConstraintSystemImpl : ConstraintSystem {
 
@@ -437,9 +438,9 @@ public class ConstraintSystemImpl : ConstraintSystem {
         return if (typeParameterDescriptor != null && isMyTypeVariable(typeParameterDescriptor)) typeParameterDescriptor else null
     }
 
-    override fun getResultingSubstitutor() = replaceUninferredBySpecialErrorType()
+    override fun getResultingSubstitutor() = replaceUninferredBySpecialErrorType().setApproximateCapturedTypes()
 
-    override fun getCurrentSubstitutor() = replaceUninferredBy(TypeUtils.DONT_CARE)
+    override fun getCurrentSubstitutor() = replaceUninferredBy(TypeUtils.DONT_CARE).setApproximateCapturedTypes()
 
     private fun createCorrespondingExtensionFunctionType(functionType: JetType, receiverType: JetType): JetType {
         assert(KotlinBuiltIns.isFunctionType(functionType))
@@ -461,3 +462,13 @@ public class ConstraintSystemImpl : ConstraintSystem {
         return KotlinBuiltIns.getInstance().getFunctionType(functionType.getAnnotations(), receiverType, arguments, returnType)
     }
 }
+
+private fun TypeSubstitutor.setApproximateCapturedTypes(): TypeSubstitutor {
+    return TypeSubstitutor.create(SubstitutionWithCapturedTypeApproximation(getSubstitution()))
+}
+
+private class SubstitutionWithCapturedTypeApproximation(val substitution: TypeSubstitution) : TypeSubstitution() {
+    override fun get(key: TypeConstructor?) = substitution[key]
+    override fun isEmpty() = substitution.isEmpty()
+    override fun approximateCapturedTypes() = true
+}

core/descriptors/src/org/jetbrains/kotlin/types/CapturedTypeApproximation.kt

@@ -74,8 +74,6 @@ public fun approximateCapturedTypesIfNecessary(typeProjection: TypeProjection?):
     if (typeProjection == null) return null
 
     val type = typeProjection.getType()
-    //todo temporary hack to compile 'kotlin'
-    if (type is LazyType) return typeProjection
     if (!TypeUtils.containsSpecialType(type, { it.isCaptured() })) {
         return typeProjection
     }
@@ -89,11 +87,10 @@ public fun approximateCapturedTypesIfNecessary(typeProjection: TypeProjection?):
 }
 
 private fun substituteCapturedTypes(typeProjection: TypeProjection): TypeProjection? {
-    val typeSubstitutor = TypeSubstitutor.create(object : TypeSubstitution {
+    val typeSubstitutor = TypeSubstitutor.create(object : TypeSubstitution() {
         override fun get(typeConstructor: TypeConstructor?): TypeProjection? {
             return (typeConstructor as? CapturedTypeConstructor)?.typeProjection
         }
-        override fun isEmpty() = false
     })
     return typeSubstitutor.substituteWithoutApproximation(typeProjection)
 }

core/descriptors/src/org/jetbrains/kotlin/types/CompositeTypeSubstitution.java

@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.types;
 
 import org.jetbrains.annotations.NotNull;
 
-public class CompositeTypeSubstitution implements TypeSubstitution {
+public class CompositeTypeSubstitution extends TypeSubstitution {
     private final TypeSubstitution[] inner;
 
     public CompositeTypeSubstitution(@NotNull TypeSubstitution... inner) {
@@ -42,6 +42,14 @@ public class CompositeTypeSubstitution implements TypeSubstitution {
         return true;
     }
 
+    @Override
+    public boolean approximateCapturedTypes() {
+        for (TypeSubstitution substitution : inner) {
+            if (substitution.approximateCapturedTypes()) return true;
+        }
+        return false;
+    }
+
     @Override
     public String toString() {
         StringBuilder builder = new StringBuilder();

core/descriptors/src/org/jetbrains/kotlin/types/DescriptorSubstitutor.java

@@ -53,6 +53,11 @@ public class DescriptorSubstitutor {
                 return originalSubstitutor.isEmpty() && mutableSubstitution.isEmpty();
             }
 
+            @Override
+            public boolean approximateCapturedTypes() {
+                return originalSubstitutor.getSubstitution().approximateCapturedTypes();
+            }
+
             @Override
             public String toString() {
                 return "DescriptorSubstitutor.substituteTypeParameters(" + mutableSubstitution + " / " + originalSubstitutor.getSubstitution() + ")";

core/descriptors/src/org/jetbrains/kotlin/types/TypeSubstitution.java

@@ -18,8 +18,8 @@ package org.jetbrains.kotlin.types;
 
 import org.jetbrains.annotations.Nullable;
 
-public interface TypeSubstitution {
-    TypeSubstitution EMPTY = new TypeSubstitution() {
+public abstract class TypeSubstitution {
+    public static final TypeSubstitution EMPTY = new TypeSubstitution() {
         @Override
         public TypeProjection get(TypeConstructor key) {
             return null;
@@ -37,6 +37,13 @@ public interface TypeSubstitution {
     };
 
     @Nullable
-    TypeProjection get(TypeConstructor key);
-    boolean isEmpty();
+    public abstract TypeProjection get(TypeConstructor key);
+
+    public boolean isEmpty() {
+        return false;
+    }
+
+    public boolean approximateCapturedTypes() {
+        return false;
+    }
 }

core/descriptors/src/org/jetbrains/kotlin/types/TypeSubstitutor.java

@@ -31,7 +31,7 @@ public class TypeSubstitutor {
 
     private static final int MAX_RECURSION_DEPTH = 100;
 
-    public static class MapToTypeSubstitutionAdapter implements TypeSubstitution {
+    public static class MapToTypeSubstitutionAdapter extends TypeSubstitution {
         private final @NotNull Map<TypeConstructor, TypeProjection> substitutionContext;
 
         public MapToTypeSubstitutionAdapter(@NotNull Map<TypeConstructor, TypeProjection> substitutionContext) {
@@ -142,6 +142,9 @@ public class TypeSubstitutor {
     @Nullable
     public TypeProjection substitute(@NotNull TypeProjection typeProjection) {
         TypeProjection substitutedTypeProjection = substituteWithoutApproximation(typeProjection);
+        if (!substitution.approximateCapturedTypes()) {
+            return substitutedTypeProjection;
+        }
         return TypesApproximationPackage.approximateCapturedTypesIfNecessary(substitutedTypeProjection);
     }