Add mechanism for type coercion in JS

Use it for char boxing/unboxing and unit materialization.
Possible to use for other purposes, for example, to add type checks
to dynamics.

See KT-18793, KT-17915, KT-19081, KT-18216, KT-12970, KT-17014,
KT-13932, KT-13930

compiler/testData/codegen/box/casts/lambdaToUnitCast.kt

@@ -1,6 +1,3 @@
-// IGNORE_BACKEND: JS
-// JS backend does not support Unit well. See KT-13932
-
 val foo: () -> Unit = {}
 
 fun box(): String {

compiler/testData/codegen/box/casts/unitAsAny.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 fun println(s: String) {
 }
 

compiler/testData/codegen/box/casts/unitAsSafeAny.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 fun println(s: String) {
 }
 

compiler/testData/codegen/box/coroutines/unitTypeReturn/suspendNonLocalReturn.kt

@@ -1,6 +1,5 @@
 // WITH_RUNTIME
 // WITH_COROUTINES
-// IGNORE_BACKEND: JS
 import helpers.*
 import kotlin.coroutines.experimental.*
 import kotlin.coroutines.experimental.intrinsics.*

compiler/testData/codegen/box/primitiveTypes/equalityWithObject/generated/primitiveEqObjectChar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS
 // Auto-generated by GeneratePrimitiveVsObjectEqualityTestData. Do not edit!
 
 val nx: Any? = '0'

compiler/testData/codegen/box/properties/kt4383.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 import kotlin.reflect.KProperty
 
 class D {

compiler/testData/codegen/box/unit/UnitValue.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 fun foo() {}
 
 fun box(): String {

compiler/testData/codegen/box/unit/kt4212.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 fun foo(): Any? = bar()
 
 fun bar() {}

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/metadata/metadataProperties.kt

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.resolve.inline.InlineStrategy
+import org.jetbrains.kotlin.types.KotlinType
 
 var JsName.staticRef: JsNode? by MetadataProperty(default = null)
 
@@ -56,12 +57,16 @@ var JsParameter.hasDefaultValue: Boolean by MetadataProperty(default = false)
 
 var JsInvocation.typeCheck: TypeCheck? by MetadataProperty(default = null)
 
-var JsInvocation.boxing: Boolean by MetadataProperty(default = false)
+var JsInvocation.boxing: BoxingKind by MetadataProperty(default = BoxingKind.NONE)
 
 var JsVars.exportedPackage: String? by MetadataProperty(default = null)
 
 var JsExpressionStatement.exportedTag: String? by MetadataProperty(default = null)
 
+var JsExpression.type: KotlinType? by MetadataProperty(default = null)
+
+var JsExpression.isUnit: Boolean by MetadataProperty(default = false)
+
 /**
  * For function and lambda bodies indicates what declaration corresponds to.
  * When absent (`null`) on body of a named function, this function is from external JS module.
@@ -143,3 +148,9 @@ enum class SpecialFunction(val suggestedName: String) {
     TO_BOXED_CHAR("toBoxedChar"),
     UNBOX_CHAR("unboxChar"),
 }
+
+enum class BoxingKind {
+    NONE,
+    BOXING,
+    UNBOXING
+}

js/js.libraries/src/builtins/arrayUtils.kt

@@ -59,7 +59,24 @@ fun charArray(size: Int, init: dynamic): Array<Char> {
 }
 
 @JsName("charArrayF")
-inline fun charArrayWithFun(size: Int, init: (Int) -> Char): Array<Char> = fillArrayFun(charArray(size, null), init)
+inline fun charArrayWithFun(size: Int, init: (Int) -> Char): Array<Char> {
+    val array = charArray(size, null)
+    for (i in 0..array.size - 1) {
+        val value = init(i)
+        js("array[i] = value;")
+    }
+    return array
+}
+
+@JsName("untypedCharArrayF")
+inline fun untypedCharArrayWithFun(size: Int, init: (Int) -> Char): Array<Char> {
+    val array = Array<Char>(size)
+    for (i in 0..array.size - 1) {
+        val value = init(i)
+        js("array[i] = value;")
+    }
+    return array
+}
 
 @JsName("longArray")
 fun longArray(size: Int, init: dynamic): Array<Long> {

js/js.libraries/src/builtins/hacks.kt

@@ -24,4 +24,4 @@ internal external annotation class JsName(val name: String)
 
 internal external annotation class native
 
-internal external fun js(code: String): dynamic
+external fun js(code: String): dynamic

js/js.tests/test/org/jetbrains/kotlin/js/test/JsLineNumberTestGenerated.java

@@ -60,12 +60,6 @@ public class JsLineNumberTestGenerated extends AbstractJsLineNumberTest {
         doTest(fileName);
     }
 
-    @TestMetadata("charBoxing.kt")
-    public void testCharBoxing() throws Exception {
-        String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/lineNumbers/charBoxing.kt");
-        doTest(fileName);
-    }
-
     @TestMetadata("classCapturingLocals.kt")
     public void testClassCapturingLocals() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/lineNumbers/classCapturingLocals.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java

@@ -795,6 +795,117 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
         }
     }
 
+    @TestMetadata("js/js.translator/testData/box/coercion")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Coercion extends AbstractBoxJsTest {
+        public void testAllFilesPresentInCoercion() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("js/js.translator/testData/box/coercion"), Pattern.compile("^([^_](.+))\\.kt$"), TargetBackend.JS, true);
+        }
+
+        @TestMetadata("classProperty.kt")
+        public void testClassProperty() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/classProperty.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("derivedFunctionReturningChar.kt")
+        public void testDerivedFunctionReturningChar() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/derivedFunctionReturningChar.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("derivedFunctionReturningUnit.kt")
+        public void testDerivedFunctionReturningUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/derivedFunctionReturningUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("destructuringToUnit.kt")
+        public void testDestructuringToUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/destructuringToUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("extensionReceiver.kt")
+        public void testExtensionReceiver() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/extensionReceiver.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("ifWithUnit.kt")
+        public void testIfWithUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/ifWithUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("inlineFunReturningUnit.kt")
+        public void testInlineFunReturningUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/inlineFunReturningUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("lambdaParameters.kt")
+        public void testLambdaParameters() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/lambdaParameters.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("loopOverUnits.kt")
+        public void testLoopOverUnits() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/loopOverUnits.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("receiverSmartCast.kt")
+        public void testReceiverSmartCast() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/receiverSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("safeCallLetReturningUnit.kt")
+        public void testSafeCallLetReturningUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/safeCallLetReturningUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("topLevelProperty.kt")
+        public void testTopLevelProperty() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/topLevelProperty.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("tryWithEmptyCatch.kt")
+        public void testTryWithEmptyCatch() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/tryWithEmptyCatch.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("unitAsExtensionReceiver.kt")
+        public void testUnitAsExtensionReceiver() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/unitAsExtensionReceiver.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("unitIsAs.kt")
+        public void testUnitIsAs() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/unitIsAs.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("unitSafeCall.kt")
+        public void testUnitSafeCall() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/unitSafeCall.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("whenWithUnit.kt")
+        public void testWhenWithUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/coercion/whenWithUnit.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("js/js.translator/testData/box/crossModuleRef")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)
@@ -7802,6 +7913,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("charArrayGetSet.kt")
+        public void testCharArrayGetSet() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/standardClasses/charArrayGetSet.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("hashMapTypeOfElement.kt")
         public void testHashMapTypeOfElement() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/standardClasses/hashMapTypeOfElement.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -2966,13 +2966,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("lambdaToUnitCast.kt")
         public void testLambdaToUnitCast() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/lambdaToUnitCast.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
         @TestMetadata("notIs.kt")
@@ -2990,13 +2984,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/unitAsAny.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
         @TestMetadata("unitAsInt.kt")
@@ -3014,13 +3002,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("unitAsSafeAny.kt")
         public void testUnitAsSafeAny() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/unitAsSafeAny.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
         @TestMetadata("unitNullableCast.kt")
@@ -6694,13 +6676,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             @TestMetadata("suspendNonLocalReturn.kt")
             public void testSuspendNonLocalReturn() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/unitTypeReturn/suspendNonLocalReturn.kt");
-                try {
+                doTest(fileName);
-                    doTest(fileName);
-                }
-                catch (Throwable ignore) {
-                    return;
-                }
-                throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
             }
 
             @TestMetadata("suspendReturn.kt")
@@ -14247,13 +14223,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 @TestMetadata("primitiveEqObjectChar.kt")
                 public void testPrimitiveEqObjectChar() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/primitiveTypes/equalityWithObject/generated/primitiveEqObjectChar.kt");
-                    try {
+                    doTest(fileName);
-                        doTest(fileName);
-                    }
-                    catch (Throwable ignore) {
-                        return;
-                    }
-                    throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
                 }
 
                 @TestMetadata("primitiveEqObjectInt.kt")
@@ -14792,13 +14762,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("kt4383.kt")
         public void testKt4383() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/properties/kt4383.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
         @TestMetadata("kt613.kt")
@@ -23603,13 +23567,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("kt4212.kt")
         public void testKt4212() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/unit/kt4212.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
         @TestMetadata("kt4265.kt")
@@ -23651,13 +23609,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("UnitValue.kt")
         public void testUnitValue() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/unit/UnitValue.kt");
-            try {
+            doTest(fileName);
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
     }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/callTranslator/CallInfo.kt

@@ -17,10 +17,14 @@
 package org.jetbrains.kotlin.js.translate.callTranslator
 
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.diagnostics.DiagnosticUtils
-import org.jetbrains.kotlin.descriptors.ReceiverParameterDescriptor
+import org.jetbrains.kotlin.js.backend.ast.JsBlock
-import org.jetbrains.kotlin.js.backend.ast.*
+import org.jetbrains.kotlin.js.backend.ast.JsConditional
+import org.jetbrains.kotlin.js.backend.ast.JsExpression
+import org.jetbrains.kotlin.js.backend.ast.JsNullLiteral
+import org.jetbrains.kotlin.js.backend.ast.metadata.type
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
 import org.jetbrains.kotlin.js.translate.reference.CallArgumentTranslator
 import org.jetbrains.kotlin.js.translate.reference.ReferenceTranslator
@@ -31,6 +35,7 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.isSafeCall
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind.*
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
+import org.jetbrains.kotlin.types.typeUtil.makeNullable
 
 interface CallInfo {
     val context: TranslationContext
@@ -99,10 +104,6 @@ fun TranslationContext.getCallInfo(
     return FunctionCallInfo(callInfo, argumentsInfo)
 }
 
-private fun TranslationContext.boxIfNeedeed(v: ReceiverValue?, d: ReceiverParameterDescriptor?, r: JsExpression?): JsExpression? {
-    return r?.let { receiver -> TranslationUtils.boxCastIfNeeded(this, receiver, v?.type, d?.type) }
-}
-
 private fun TranslationContext.getDispatchReceiver(receiverValue: ReceiverValue): JsExpression {
     return getDispatchReceiver(getReceiverParameterForReceiver(receiverValue))
 }
@@ -134,6 +135,10 @@ private fun TranslationContext.createCallInfo(
     }
 
     var dispatchReceiver = getDispatchReceiver()
+    var dispatchReceiverType = resolvedCall.smartCastDispatchReceiverType ?: resolvedCall.dispatchReceiver?.type
+    if (dispatchReceiverType != null && (resolvedCall.resultingDescriptor as? FunctionDescriptor)?.kind?.isReal == false) {
+        dispatchReceiverType = TranslationUtils.getDispatchReceiverTypeForCoercion(resolvedCall.resultingDescriptor)
+    }
     var extensionReceiver = getExtensionReceiver()
     var notNullConditional: JsConditional? = null
 
@@ -154,16 +159,19 @@ private fun TranslationContext.createCallInfo(
         val container = resolvedCall.resultingDescriptor.containingDeclaration
         if (DescriptorUtils.isObject(container)) {
             dispatchReceiver = ReferenceTranslator.translateAsValueReference(container, this)
+            dispatchReceiverType = (container as ClassDescriptor).defaultType
         }
     }
 
-    dispatchReceiver = boxIfNeedeed(resolvedCall.dispatchReceiver,
+    if (dispatchReceiverType != null) {
-                                    resolvedCall.candidateDescriptor.dispatchReceiverParameter,
+        dispatchReceiver = dispatchReceiver?.let {
-                                    dispatchReceiver)
+            TranslationUtils.coerce(this, it, dispatchReceiverType!!)
+        }
+    }
 
-    extensionReceiver = boxIfNeedeed(resolvedCall.extensionReceiver,
+    extensionReceiver = extensionReceiver?.let {
-                                     resolvedCall.candidateDescriptor.extensionReceiverParameter,
+        TranslationUtils.coerce(this, it, resolvedCall.candidateDescriptor.extensionReceiverParameter!!.type)
-                                     extensionReceiver)
+    }
 
 
     return object : AbstractCallInfo(), CallInfo {
@@ -179,7 +187,9 @@ private fun TranslationContext.createCallInfo(
                 result
             }
             else {
-                notNullConditionalForSafeCall.thenExpression = result
+                val type = resolvedCall.getReturnType()
+                result.type = type
+                notNullConditionalForSafeCall.thenExpression = TranslationUtils.coerce(context, result, type.makeNullable())
                 notNullConditionalForSafeCall
             }
         }

js/js.translator/src/org/jetbrains/kotlin/js/translate/callTranslator/CallTranslator.kt

@@ -31,11 +31,14 @@ import org.jetbrains.kotlin.js.translate.utils.*
 import org.jetbrains.kotlin.psi.Call.CallType
 import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.resolve.calls.callResolverUtil.isInvokeCallOnVariable
+import org.jetbrains.kotlin.resolve.calls.callUtil.isSafeCall
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.VariableAsFunctionResolvedCall
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind.*
 import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
+import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.typeUtil.makeNullable
 
 object CallTranslator {
     @JvmOverloads
@@ -52,7 +55,9 @@ object CallTranslator {
                      extensionOrDispatchReceiver: JsExpression? = null
     ): JsExpression {
         val variableAccessInfo = VariableAccessInfo(context.getCallInfo(resolvedCall, extensionOrDispatchReceiver), null)
-        return variableAccessInfo.translateVariableAccess().source(resolvedCall.call.callElement)
+        val result = variableAccessInfo.translateVariableAccess().source(resolvedCall.call.callElement)
+        result.type = TranslationUtils.getReturnTypeForCoercion(resolvedCall.resultingDescriptor.original)
+        return result
     }
 
     fun translateSet(context: TranslationContext,
@@ -61,7 +66,9 @@ object CallTranslator {
                      extensionOrDispatchReceiver: JsExpression? = null
     ): JsExpression {
         val variableAccessInfo = VariableAccessInfo(context.getCallInfo(resolvedCall, extensionOrDispatchReceiver), value)
-        return variableAccessInfo.translateVariableAccess().source(resolvedCall.call.callElement)
+        val result = variableAccessInfo.translateVariableAccess().source(resolvedCall.call.callElement)
+        result.type = context.currentModule.builtIns.unitType
+        return result
     }
 
     fun buildCall(context: TranslationContext,
@@ -95,7 +102,7 @@ private fun translateCall(
         assert(explicitReceivers.extensionReceiver == null) { "VariableAsFunctionResolvedCall must have one receiver" }
         val variableCall = resolvedCall.variableCall
 
-        return if (variableCall.expectedReceivers()) {
+        val result = if (variableCall.expectedReceivers()) {
             val newReceiver = CallTranslator.translateGet(context, variableCall, explicitReceivers.extensionOrDispatchReceiver)
             translateFunctionCall(context, resolvedCall.functionCall, resolvedCall.variableCall, ExplicitReceivers(newReceiver))
         } else {
@@ -110,6 +117,8 @@ private fun translateCall(
                                       ExplicitReceivers(dispatchReceiver, explicitReceivers.extensionOrDispatchReceiver))
             }
         }
+
+        return result
     }
 
     val call = resolvedCall.call
@@ -151,9 +160,13 @@ private fun translateFunctionCall(
             callExpression.isTailCallSuspend = true
         }
     }
+
+    callExpression.type = resolvedCall.getReturnType().let { if (resolvedCall.call.isSafeCall()) it.makeNullable() else it }
     return callExpression
 }
 
+fun ResolvedCall<out CallableDescriptor>.getReturnType(): KotlinType = TranslationUtils.getReturnTypeForCoercion(resultingDescriptor)
+
 private val TranslationContext.isInStateMachine
     get() = (declarationDescriptor as? FunctionDescriptor)?.requiresStateMachineTransformation(this) == true
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/context/TemporaryConstVariable.java

@@ -24,7 +24,7 @@ public final class TemporaryConstVariable extends TemporaryVariable{
     private boolean initialized = false;
 
     public TemporaryConstVariable(@NotNull JsName variableName, @NotNull JsExpression assignmentExpression) {
-        super(variableName, assignmentExpression);
+        super(variableName, assignmentExpression, null);
     }
 
     @NotNull

js/js.translator/src/org/jetbrains/kotlin/js/translate/context/TemporaryVariable.java

@@ -21,33 +21,40 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.js.backend.ast.*;
 import org.jetbrains.kotlin.js.backend.ast.metadata.MetadataProperties;
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
+import org.jetbrains.kotlin.types.KotlinType;
 
 public class TemporaryVariable {
 
     /*package*/ static TemporaryVariable create(@NotNull JsName temporaryName, @Nullable JsExpression initExpression) {
         JsBinaryOperation rhs = null;
+        KotlinType type = null;
         if (initExpression != null) {
             rhs = JsAstUtils.assignment(temporaryName.makeRef(), initExpression);
             rhs.source(initExpression.getSource());
             MetadataProperties.setSynthetic(rhs, true);
+            type = MetadataProperties.getType(initExpression);
         }
-        return new TemporaryVariable(temporaryName, rhs);
+        return new TemporaryVariable(temporaryName, rhs, type);
     }
 
     @Nullable
     private final JsExpression assignmentExpression;
     @NotNull
     private final JsName variableName;
+    @Nullable
+    private final KotlinType type;
 
-    protected TemporaryVariable(@NotNull JsName temporaryName, @Nullable JsExpression assignmentExpression) {
+    protected TemporaryVariable(@NotNull JsName temporaryName, @Nullable JsExpression assignmentExpression, @Nullable KotlinType type) {
         this.variableName = temporaryName;
         this.assignmentExpression = assignmentExpression;
+        this.type = type;
     }
 
     @NotNull
     public JsNameRef reference() {
         JsNameRef result = variableName.makeRef();
         MetadataProperties.setSynthetic(result, true);
+        MetadataProperties.setType(result, type);
         return result;
     }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/PropertyTranslator.kt

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.js.translate.general.Translation
 import org.jetbrains.kotlin.js.translate.utils.BindingUtils
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils.pureFqn
 import org.jetbrains.kotlin.js.translate.utils.JsDescriptorUtils
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
 import org.jetbrains.kotlin.js.translate.utils.TranslationUtils.*
 import org.jetbrains.kotlin.js.translate.utils.finalElement
 import org.jetbrains.kotlin.js.translate.utils.jsAstUtils.addParameter
@@ -172,7 +173,7 @@ fun TranslationContext.translateDelegateOrInitializerExpression(expression: KtPr
         CallTranslator.translate(innerContext, provideDelegateCall, initializer)
     }
     else {
-        initializer
+        TranslationUtils.coerce(this, initializer, propertyDescriptor.type)
     }
 }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/DestructuringDeclarationTranslator.java

@@ -84,8 +84,7 @@ public class DestructuringDeclarationTranslator extends AbstractTranslator {
                 setInlineCallMetadata(entryInitializer, entry, entryInitCall, context());
             }
 
-            entryInitializer = TranslationUtils.boxCastIfNeeded(context(), entryInitializer, candidateDescriptor.getReturnType(),
+            entryInitializer = TranslationUtils.coerce(context(), entryInitializer, descriptor.getType());
-                                                                descriptor.getType());
 
             JsName name = context().getNameForDescriptor(descriptor);
             if (isVarCapturedInClosure(context().bindingContext(), descriptor)) {

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/ExpressionVisitor.java

@@ -20,7 +20,6 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor;
 import org.jetbrains.kotlin.descriptors.annotations.KotlinRetention;
@@ -39,6 +38,8 @@ import org.jetbrains.kotlin.js.translate.utils.BindingUtils;
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
 import org.jetbrains.kotlin.js.translate.utils.TranslationUtils;
 import org.jetbrains.kotlin.js.translate.utils.UtilsKt;
+import org.jetbrains.kotlin.js.translate.utils.mutator.CoercionMutator;
+import org.jetbrains.kotlin.js.translate.utils.mutator.LastExpressionMutator;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.psi.psiUtil.PsiUtilsKt;
 import org.jetbrains.kotlin.resolve.BindingContext;
@@ -107,6 +108,11 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
                 jsBlock.getStatements().add(jsStatement);
             }
         }
+        if (statements.isEmpty()) {
+            ClassDescriptor unitClass = context.getCurrentModule().getBuiltIns().getUnit();
+            jsBlock.getStatements().add(JsAstUtils.asSyntheticStatement(
+                    ReferenceTranslator.translateAsValueReference(unitClass, context)));
+        }
         return jsBlock;
     }
 
@@ -135,6 +141,8 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
             return new JsReturn(ref.source(jetReturnExpression));
         }
 
+        FunctionDescriptor returnTarget = getNonLocalReturnTarget(jetReturnExpression, context);
+
         JsReturn jsReturn;
         if (returned == null) {
             jsReturn = new JsReturn(null);
@@ -146,15 +154,19 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
             assert returnedType != null : "Resolved return expression is expected to have type: " +
                                           PsiUtilsKt.getTextWithLocation(jetReturnExpression);
 
-            if (KotlinBuiltIns.isCharOrNullableChar(returnedType) &&
+            CallableDescriptor returnTargetOrCurrentFunction = returnTarget;
-                TranslationUtils.shouldBoxReturnValue((CallableDescriptor)context.getDeclarationDescriptor())) {
+            if (returnTargetOrCurrentFunction == null) {
-                jsReturnExpression = TranslationUtils.charToBoxedChar(context, jsReturnExpression);
+                returnTargetOrCurrentFunction = (CallableDescriptor) context.getDeclarationDescriptor();
+            }
+            if (returnTargetOrCurrentFunction != null) {
+                jsReturnExpression = TranslationUtils.coerce(context, jsReturnExpression,
+                                                             TranslationUtils.getReturnTypeForCoercion(returnTargetOrCurrentFunction));
             }
 
             jsReturn = new JsReturn(jsReturnExpression);
         }
 
-        MetadataProperties.setReturnTarget(jsReturn, getNonLocalReturnTarget(jetReturnExpression, context));
+        MetadataProperties.setReturnTarget(jsReturn, returnTarget);
 
         return jsReturn.source(jetReturnExpression);
     }
@@ -245,10 +257,7 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
 
         if (lhs instanceof DoubleColonLHS.Expression && !((DoubleColonLHS.Expression) lhs).isObjectQualifier()) {
             JsExpression receiver = translateAsExpression(receiverExpression, context);
-            KotlinType type = context.bindingContext().getType(receiverExpression);
+            receiver = TranslationUtils.coerce(context, receiver, context.getCurrentModule().getBuiltIns().getAnyType());
-            if (type != null && KotlinBuiltIns.isChar(type)) {
-                receiver = TranslationUtils.charToBoxedChar(context, receiver);
-            }
             return new JsInvocation(context.namer().kotlin(GET_KCLASS_FROM_EXPRESSION), receiver);
         }
 
@@ -270,6 +279,7 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
     public JsNode visitIfExpression(@NotNull KtIfExpression expression, @NotNull TranslationContext context) {
         assert expression.getCondition() != null : "condition should not ne null: " + expression.getText();
         JsExpression testExpression = Translation.translateAsExpression(expression.getCondition(), context);
+        KotlinType type = context.bindingContext().getType(expression);
 
         boolean isKotlinExpression = BindingContextUtilsKt.isUsedAsExpression(expression, context.bindingContext());
 
@@ -281,6 +291,15 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
         JsStatement elseStatement =
                 elseExpression != null ? Translation.translateAsStatementAndMergeInBlockIfNeeded(elseExpression, context) : null;
 
+        if (type != null) {
+            if (thenStatement != null) {
+                thenStatement = LastExpressionMutator.mutateLastExpression(thenStatement, new CoercionMutator(type, context));
+            }
+            if (elseStatement != null) {
+                elseStatement = LastExpressionMutator.mutateLastExpression(elseStatement, new CoercionMutator(type, context));
+            }
+        }
+
         if (isKotlinExpression) {
             JsExpression jsThenExpression = JsAstUtils.extractExpressionFromStatement(thenStatement);
             JsExpression jsElseExpression = JsAstUtils.extractExpressionFromStatement(elseStatement);

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/FunctionTranslator.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.backend.ast.metadata.descriptor
 import org.jetbrains.kotlin.js.backend.ast.metadata.functionDescriptor
 import org.jetbrains.kotlin.js.backend.ast.metadata.hasDefaultValue
+import org.jetbrains.kotlin.js.backend.ast.metadata.type
 import org.jetbrains.kotlin.js.config.JSConfigurationKeys
 import org.jetbrains.kotlin.js.descriptorUtils.shouldBeExported
 import org.jetbrains.kotlin.js.inline.util.FunctionWithWrapper
@@ -58,7 +59,9 @@ fun TranslationContext.translateAndAliasParameters(
 
     if (descriptor.requiresExtensionReceiverParameter) {
         val receiverParameterName = JsScope.declareTemporaryName(Namer.getReceiverParameterName())
-        aliases[descriptor.extensionReceiverParameter!!] = receiverParameterName.makeRef()
+        val receiverRef = receiverParameterName.makeRef()
+        receiverRef.type = descriptor.extensionReceiverParameter!!.type
+        aliases[descriptor.extensionReceiverParameter!!] = receiverRef
         targetList += JsParameter(receiverParameterName)
     }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/LoopTranslator.kt

@@ -19,6 +19,7 @@
 package org.jetbrains.kotlin.js.translate.expression
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.translate.callTranslator.CallTranslator
@@ -29,6 +30,7 @@ import org.jetbrains.kotlin.js.translate.utils.BindingUtils.*
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils.*
 import org.jetbrains.kotlin.js.translate.utils.PsiUtils.getLoopRange
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
@@ -142,7 +144,10 @@ fun translateForExpression(expression: KtForExpression, context: TranslationCont
 
             val currentVarInit =
                 if (destructuringParameter == null) {
-                    newVar(parameterName, itemValue).apply { source = expression.loopRange }
+                    val loopParameterDescriptor = (getDescriptorForElement(context.bindingContext(), loopParameter) as CallableDescriptor)
+                    val loopParameterType = loopParameterDescriptor.returnType ?: context.currentModule.builtIns.anyType
+                    val coercedItemValue = itemValue?.let { TranslationUtils.coerce(context, it, loopParameterType) }
+                    newVar(parameterName, coercedItemValue).apply { source = expression.loopRange }
                 }
                 else {
                     val innerBlockContext = context.innerBlock(block)
@@ -224,7 +229,7 @@ fun translateForExpression(expression: KtForExpression, context: TranslationCont
 
     fun translateForOverArray(): JsStatement {
         val rangeExpression = context.defineTemporary(Translation.translateAsExpression(loopRange, context))
-        val length = ArrayFIF.LENGTH_PROPERTY_INTRINSIC.apply(rangeExpression, listOf<JsExpression>(), context)
+        val length = ArrayFIF.LENGTH_PROPERTY_INTRINSIC.apply(rangeExpression, listOf(), context)
         val end = context.defineTemporary(length)
         val index = context.declareTemporary(JsIntLiteral(0), expression)
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/PatternTranslator.java

@@ -81,10 +81,8 @@ public final class PatternTranslator extends AbstractTranslator {
         KtTypeReference typeReference = expression.getRight();
         assert typeReference != null: "Cast expression must have type reference";
 
-        KotlinType leftType = context().bindingContext().getType(left);
+        KotlinType anyType = context().getCurrentModule().getBuiltIns().getAnyType();
-        if (leftType != null && KotlinBuiltIns.isChar(leftType)) {
+        expressionToCast = TranslationUtils.coerce(context(), expressionToCast, anyType);
-            expressionToCast = TranslationUtils.charToBoxedChar(context(), expressionToCast);
-        }
 
         TemporaryVariable temporary = context().declareTemporary(expressionToCast, expression);
         JsExpression isCheck = translateIsCheck(temporary.assignmentExpression(), typeReference);
@@ -102,12 +100,11 @@ public final class PatternTranslator extends AbstractTranslator {
 
         JsExpression result = new JsConditional(isCheck, temporary.reference(), onFail);
 
-        KotlinType expressionType = context().bindingContext().getType(expression);
+        KotlinType targetType = getTypeByReference(bindingContext(), typeReference);
-        if (expressionType != null && KotlinBuiltIns.isCharOrNullableChar(expressionType)) {
+        if (isSafeCast(expression)) {
-            result = TranslationUtils.boxedCharToChar(context(), result);
+            targetType = targetType.unwrap().makeNullableAsSpecified(true);
         }
-
+        return TranslationUtils.coerce(context(), result, targetType);
-        return result;
     }
 
     @NotNull
@@ -115,10 +112,8 @@ public final class PatternTranslator extends AbstractTranslator {
         KtExpression left = expression.getLeftHandSide();
         JsExpression expressionToCheck = Translation.translateAsExpression(left, context());
 
-        KotlinType leftType = context().bindingContext().getType(left);
+        KotlinType anyType = context().getCurrentModule().getBuiltIns().getAnyType();
-        if (leftType != null && KotlinBuiltIns.isChar(leftType)) {
+        expressionToCheck = TranslationUtils.coerce(context(), expressionToCheck, anyType);
-            expressionToCheck = TranslationUtils.charToBoxedChar(context(), expressionToCheck);
-        }
 
         KtTypeReference typeReference = expression.getTypeReference();
         assert typeReference != null;

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/WhenTranslator.java

@@ -28,6 +28,8 @@ import org.jetbrains.kotlin.js.translate.general.Translation;
 import org.jetbrains.kotlin.js.translate.operation.InOperationTranslator;
 import org.jetbrains.kotlin.js.translate.utils.BindingUtils;
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
+import org.jetbrains.kotlin.js.translate.utils.mutator.CoercionMutator;
+import org.jetbrains.kotlin.js.translate.utils.mutator.LastExpressionMutator;
 import org.jetbrains.kotlin.lexer.KtTokens;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.psi.psiUtil.PsiUtilsKt;
@@ -50,6 +52,9 @@ public final class WhenTranslator extends AbstractTranslator {
     @Nullable
     private final JsExpression expressionToMatch;
 
+    @Nullable
+    private final KotlinType type;
+
     private WhenTranslator(@NotNull KtWhenExpression expression, @NotNull TranslationContext context) {
         super(context);
 
@@ -57,6 +62,8 @@ public final class WhenTranslator extends AbstractTranslator {
 
         KtExpression subject = expression.getSubjectExpression();
         expressionToMatch = subject != null ? context.defineTemporary(Translation.translateAsExpression(subject, context)) : null;
+
+        type = context().bindingContext().getType(expression);
     }
 
     private JsNode translate() {
@@ -106,13 +113,18 @@ public final class WhenTranslator extends AbstractTranslator {
     }
 
     @NotNull
-    private static JsStatement translateEntryExpression(
+    private JsStatement translateEntryExpression(
             @NotNull KtWhenEntry entry,
             @NotNull TranslationContext context,
             @NotNull JsBlock block) {
         KtExpression expressionToExecute = entry.getExpression();
         assert expressionToExecute != null : "WhenEntry should have whenExpression to execute.";
-        return Translation.translateAsStatement(expressionToExecute, context, block);
+        JsStatement result = Translation.translateAsStatement(expressionToExecute, context, block);
+        if (type != null) {
+            return LastExpressionMutator.mutateLastExpression(result, new CoercionMutator(type, context));
+        }
+
+        return result;
     }
 
     @NotNull

js/js.translator/src/org/jetbrains/kotlin/js/translate/general/Translation.java

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.descriptors.FunctionDescriptor;
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor;
 import org.jetbrains.kotlin.idea.MainFunctionDetector;
 import org.jetbrains.kotlin.js.backend.ast.*;
+import org.jetbrains.kotlin.js.backend.ast.metadata.MetadataProperties;
 import org.jetbrains.kotlin.js.config.JsConfig;
 import org.jetbrains.kotlin.js.facade.MainCallParameters;
 import org.jetbrains.kotlin.js.facade.TranslationUnit;
@@ -123,6 +124,15 @@ public final class Translation {
     ) {
         KotlinType expectedType = context.bindingContext().getType(expression);
         ConstantValue<?> constant = compileTimeValue.toConstantValue(expectedType != null ? expectedType : TypeUtils.NO_EXPECTED_TYPE);
+        JsExpression result = translateConstantWithoutType(constant);
+        if (result != null) {
+            MetadataProperties.setType(result, expectedType);
+        }
+        return result;
+    }
+
+    @Nullable
+    private static JsExpression translateConstantWithoutType(@NotNull ConstantValue<?> constant) {
         if (constant instanceof NullValue) {
             return new JsNullLiteral();
         }
@@ -187,10 +197,17 @@ public final class Translation {
             @NotNull JsBlock block
     ) {
         JsNode jsNode = translateExpression(expression, context, block);
+
         if (jsNode instanceof JsExpression) {
-            KotlinType expressionType = context.bindingContext().getType(expression);
+            JsExpression jsExpression = (JsExpression) jsNode;
-            return unboxIfNeeded(context, (JsExpression) jsNode,
+            KotlinType type = context.bindingContext().getType(expression);
-                                 expressionType != null && KotlinBuiltIns.isCharOrNullableChar(expressionType));
+            if (MetadataProperties.getType(jsExpression) == null) {
+                MetadataProperties.setType(jsExpression, type);
+            }
+            else if (type != null) {
+                jsExpression = TranslationUtils.coerce(context, jsExpression, type);
+            }
+            return jsExpression;
         }
 
         assert jsNode instanceof JsStatement : "Unexpected node of type: " + jsNode.getClass().toString();
@@ -198,27 +215,15 @@ public final class Translation {
             TemporaryVariable result = context.declareTemporary(null, expression);
             AssignToExpressionMutator saveResultToTemporaryMutator = new AssignToExpressionMutator(result.reference());
             block.getStatements().add(mutateLastExpression(jsNode, saveResultToTemporaryMutator));
-            return result.reference();
+            JsExpression tmpVar = result.reference();
+            MetadataProperties.setType(tmpVar, context.bindingContext().getType(expression));
+            return tmpVar;
         }
 
         block.getStatements().add(convertToStatement(jsNode));
         return new JsNullLiteral().source(expression);
     }
 
-    @NotNull
-    public static JsExpression unboxIfNeeded(
-            @NotNull TranslationContext context,
-            @NotNull JsExpression expression,
-            boolean charOrNullableChar
-    ) {
-        if (charOrNullableChar &&
-            (expression instanceof JsInvocation || expression instanceof JsNameRef || expression instanceof JsArrayAccess)
-        ) {
-            expression = TranslationUtils.boxedCharToChar(context, expression);
-        }
-        return expression;
-    }
-
     @NotNull
     public static JsStatement translateAsStatement(@NotNull KtExpression expression, @NotNull TranslationContext context) {
         return translateAsStatement(expression, context, context.dynamicContext().jsBlock());

js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/functions/FunctionIntrinsics.java

@@ -50,6 +50,7 @@ public final class FunctionIntrinsics {
         register(NumberAndCharConversionFIF.INSTANCE);
         register(ThrowableConstructorIntrinsicFactory.INSTANCE);
         register(ExceptionPropertyIntrinsicFactory.INSTANCE);
+        register(AsDynamicFIF.INSTANCE);
     }
 
     private void register(@NotNull FunctionIntrinsicFactory instance) {

js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/functions/factories/ArrayFIF.kt

@@ -43,7 +43,7 @@ import java.util.*
 
 object ArrayFIF : CompositeFIF() {
     @JvmField
-    val GET_INTRINSIC = intrinsify { callInfo, arguments, _ ->
+    val GET_INTRINSIC = intrinsify { callInfo, arguments, context ->
         assert(arguments.size == 1) { "Array get expression must have one argument." }
         val (indexExpression) = arguments
         JsArrayAccess(callInfo.dispatchReceiver, indexExpression)
@@ -108,7 +108,12 @@ object ArrayFIF : CompositeFIF() {
             }
         }
         else {
-            "kotlin.newArrayF"
+            if (primitiveType == CHAR) {
+                "kotlin.untypedCharArrayF"
+            }
+            else {
+                "kotlin.newArrayF"
+            }
         }
     }
 
@@ -183,7 +188,7 @@ object ArrayFIF : CompositeFIF() {
                 }
             }
             else {
-                JsAstUtils.invokeKotlinFunction("newArrayF", size, fn)
+                JsAstUtils.invokeKotlinFunction(if (type == CHAR) "untypedCharArrayF" else "newArrayF", size, fn)
             }
             invocation.inlineStrategy = InlineStrategy.IN_PLACE
             val descriptor = callInfo.resolvedCall.resultingDescriptor.original

js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/functions/factories/AsDynamicFIF.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2010-2017 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.
+ */
+
+package org.jetbrains.kotlin.js.translate.intrinsic.functions.factories
+
+import org.jetbrains.kotlin.js.backend.ast.JsExpression
+import org.jetbrains.kotlin.js.patterns.PatternBuilder
+import org.jetbrains.kotlin.js.translate.callTranslator.CallInfo
+import org.jetbrains.kotlin.js.translate.context.TranslationContext
+import org.jetbrains.kotlin.js.translate.intrinsic.functions.basic.FunctionIntrinsic
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
+
+object AsDynamicFIF : CompositeFIF() {
+    init {
+        add(PatternBuilder.pattern("kotlin.js.asDynamic()"), object : FunctionIntrinsic() {
+            override fun apply(callInfo: CallInfo, arguments: List<JsExpression>, context: TranslationContext): JsExpression =
+                    TranslationUtils.coerce(context, callInfo.extensionReceiver!!, callInfo.resolvedCall.extensionReceiver!!.type)
+        })
+    }
+}

js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/functions/factories/TopLevelFIF.java

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.js.translate.intrinsic.functions.basic.FunctionIntrinsic;
 import org.jetbrains.kotlin.js.translate.intrinsic.functions.basic.FunctionIntrinsicWithReceiverComputed;
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils;
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils;
 import org.jetbrains.kotlin.js.translate.utils.UtilsKt;
 import org.jetbrains.kotlin.resolve.DescriptorFactory;
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
@@ -166,13 +167,14 @@ public final class TopLevelFIF extends CompositeFIF {
     public static final KotlinFunctionIntrinsic TO_STRING = new KotlinFunctionIntrinsic("toString");
 
     @NotNull
-    public static final FunctionIntrinsic CHAR_TO_STRING = new FunctionIntrinsicWithReceiverComputed() {
+    private static final FunctionIntrinsic CHAR_TO_STRING = new FunctionIntrinsicWithReceiverComputed() {
         @NotNull
         @Override
         public JsExpression apply(
                 @Nullable JsExpression receiver, @NotNull List<? extends JsExpression> arguments, @NotNull TranslationContext context
         ) {
             assert receiver != null;
+            receiver = TranslationUtils.coerce(context, receiver, context.getCurrentModule().getBuiltIns().getCharType());
             return JsAstUtils.charToString(receiver);
         }
     };

js/js.translator/src/org/jetbrains/kotlin/js/translate/intrinsic/operation/EqualsBOIF.kt

@@ -24,7 +24,6 @@ import org.jetbrains.kotlin.js.backend.ast.JsBinaryOperator
 import org.jetbrains.kotlin.js.backend.ast.JsExpression
 import org.jetbrains.kotlin.js.backend.ast.JsNullLiteral
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
-import org.jetbrains.kotlin.js.translate.general.Translation
 import org.jetbrains.kotlin.js.translate.intrinsic.functions.factories.TopLevelFIF
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils
 import org.jetbrains.kotlin.js.translate.utils.PsiUtils.getOperationToken
@@ -57,13 +56,15 @@ object EqualsBOIF : BinaryOperationIntrinsicFactory {
 
             val ktLeft = checkNotNull(expression.left) { "No left-hand side: " + expression.text }
             val ktRight = checkNotNull(expression.right) { "No right-hand side: " + expression.text }
-            val leftType = getRefinedType(ktLeft, context)?.let { KotlinBuiltIns.getPrimitiveType(it) }
+            val leftKotlinType = getRefinedType(ktLeft, context)
-            val rightType = getRefinedType(ktRight, context)?.let { KotlinBuiltIns.getPrimitiveType(it) }
+            val rightKotlinType = getRefinedType(ktRight, context)
+            val leftType = leftKotlinType?.let { KotlinBuiltIns.getPrimitiveType(it) }
+            val rightType = rightKotlinType?.let { KotlinBuiltIns.getPrimitiveType(it) }
 
             if (leftType != null && (leftType in SIMPLE_PRIMITIVES || leftType == rightType && leftType != PrimitiveType.LONG)) {
-                return JsBinaryOperation(if (isNegated) JsBinaryOperator.REF_NEQ else JsBinaryOperator.REF_EQ,
+                val coercedLeft = TranslationUtils.coerce(context, left, leftKotlinType)
-                                         Translation.unboxIfNeeded(context, left, leftType == PrimitiveType.CHAR),
+                val coercedRight = TranslationUtils.coerce(context, right, rightKotlinType!!)
-                                         Translation.unboxIfNeeded(context, right, rightType == PrimitiveType.CHAR))
+                return JsBinaryOperation(if (isNegated) JsBinaryOperator.REF_NEQ else JsBinaryOperator.REF_EQ, coercedLeft, coercedRight)
             }
 
             val resolvedCall = expression.getResolvedCall(context.bindingContext())
@@ -77,10 +78,10 @@ object EqualsBOIF : BinaryOperationIntrinsicFactory {
                 return JsBinaryOperation(if (isNegated) JsBinaryOperator.NEQ else JsBinaryOperator.EQ, left, right)
             }
 
-            val maybeBoxedLeft = if (leftType == PrimitiveType.CHAR) TranslationUtils.charToBoxedChar(context, left) else left
+            val anyType = context.currentModule.builtIns.anyType
-            val maybeBoxedRight = if (rightType == PrimitiveType.CHAR) TranslationUtils.charToBoxedChar(context, right) else right
+            val coercedLeft = TranslationUtils.coerce(context, left, anyType)
-
+            val coercedRight = TranslationUtils.coerce(context, right, anyType)
-            val result = TopLevelFIF.KOTLIN_EQUALS.apply(maybeBoxedLeft, Arrays.asList<JsExpression>(maybeBoxedRight), context)
+            val result = TopLevelFIF.KOTLIN_EQUALS.apply(coercedLeft, listOf(coercedRight), context)
             return if (isNegated) JsAstUtils.not(result) else result
         }
 

js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/BinaryOperationTranslator.java

@@ -126,15 +126,14 @@ public final class BinaryOperationTranslator extends AbstractTranslator {
     @NotNull
     private JsExpression translateElvis() {
         KotlinType expressionType = context().bindingContext().getType(expression);
+        assert expressionType != null;
 
-        JsExpression leftExpression = TranslationUtils.boxCastIfNeeded(
+        JsExpression leftExpression = TranslationUtils.coerce(
-                context(), Translation.translateAsExpression(leftKtExpression, context()),
+                context(), Translation.translateAsExpression(leftKtExpression, context()), expressionType);
-                context().bindingContext().getType(leftKtExpression), expressionType);
 
         JsBlock rightBlock = new JsBlock();
-        JsExpression rightExpression = TranslationUtils.boxCastIfNeeded(
+        JsExpression rightExpression = TranslationUtils.coerce(
-                context(),Translation.translateAsExpression(rightKtExpression, context(), rightBlock),
+                context(), Translation.translateAsExpression(rightKtExpression, context(), rightBlock), expressionType);
-                context().bindingContext().getType(rightKtExpression), expressionType);
 
         if (rightBlock.isEmpty()) {
             return TranslationUtils.notNullConditional(leftExpression, rightExpression, context());

js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/IntrinsicAssignmentTranslator.java

@@ -66,7 +66,7 @@ public final class IntrinsicAssignmentTranslator extends AssignmentTranslator {
             if (leftType != null && KotlinBuiltIns.isStringOrNullableString(leftType)) {
                 result = JsAstUtils.charToString(result);
             }
-            else if (leftType == null || !KotlinBuiltIns.isCharOrNullableChar(leftType)) {
+            else if (leftType != null && !KotlinBuiltIns.isCharOrNullableChar(leftType)) {
                 result = TranslationUtils.charToBoxedChar(context, result);
             }
         }

js/js.translator/src/org/jetbrains/kotlin/js/translate/reference/CallArgumentTranslator.kt

@@ -17,9 +17,10 @@
 package org.jetbrains.kotlin.js.translate.reference
 
 import org.jetbrains.kotlin.backend.common.isBuiltInSuspendCoroutineOrReturn
-import org.jetbrains.kotlin.builtins.DefaultBuiltIns
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.builtins.PrimitiveType
+import org.jetbrains.kotlin.builtins.functions.FunctionInvokeDescriptor
+import org.jetbrains.kotlin.builtins.getFunctionalClassKind
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
 import org.jetbrains.kotlin.js.backend.ast.*
@@ -36,9 +37,9 @@ import org.jetbrains.kotlin.js.translate.utils.AnnotationsUtils
 import org.jetbrains.kotlin.js.translate.utils.JsAstUtils
 import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
 import org.jetbrains.kotlin.js.translate.utils.getReferenceToJsClass
-import org.jetbrains.kotlin.psi.Call
 import org.jetbrains.kotlin.psi.ValueArgument
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.calls.components.isVararg
 import org.jetbrains.kotlin.resolve.calls.model.DefaultValueArgument
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedValueArgument
@@ -191,18 +192,15 @@ class CallArgumentTranslator private constructor(
             val parenthisedArgumentExpression = arg.getArgumentExpression()
 
             val param = argsToParameters[arg]!!.original
-            val parameterType = if (resolvedCall.call.callType == Call.CallType.INVOKE) {
+            val isLambda = resolvedCall.resultingDescriptor.let { it.getFunctionalClassKind() != null || it is FunctionInvokeDescriptor }
-                DefaultBuiltIns.Instance.anyType
+            val parameterType = if (!isLambda) param.varargElementType ?: param.type else context.currentModule.builtIns.anyType
-            }
+
-            else {
+            var argJs = Translation.translateAsExpression(parenthisedArgumentExpression!!, argumentContext)
-                param.varargElementType ?: param.type
+            if (!param.isVararg || arg.getSpreadElement() == null) {
+                argJs = TranslationUtils.coerce(context, argJs, parameterType)
             }
 
-            val argType = context.bindingContext().getType(parenthisedArgumentExpression!!)
+            arg to argJs
-
-            val argJs = Translation.translateAsExpression(parenthisedArgumentExpression, argumentContext)
-
-            arg to TranslationUtils.boxCastIfNeeded(context, argJs, argType, parameterType)
         }
 
         val resolvedOrder = resolvedCall.valueArgumentsByIndex.orEmpty()

js/js.translator/src/org/jetbrains/kotlin/js/translate/reference/CallableReferenceTranslator.kt

@@ -22,11 +22,13 @@ import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.backend.ast.metadata.SideEffectKind
 import org.jetbrains.kotlin.js.backend.ast.metadata.isCallableReference
 import org.jetbrains.kotlin.js.backend.ast.metadata.sideEffects
+import org.jetbrains.kotlin.js.backend.ast.metadata.type
 import org.jetbrains.kotlin.js.translate.callTranslator.CallTranslator
 import org.jetbrains.kotlin.js.translate.context.Namer
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
 import org.jetbrains.kotlin.js.translate.general.Translation
 import org.jetbrains.kotlin.js.translate.utils.BindingUtils
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils
 import org.jetbrains.kotlin.js.translate.utils.finalElement
 import org.jetbrains.kotlin.psi.KtCallableReferenceExpression
 import org.jetbrains.kotlin.psi.KtExpression
@@ -107,15 +109,19 @@ object CallableReferenceTranslator {
             null
         }
 
+        val functionDescriptor = realResolvedCall.resultingDescriptor
         val aliases = mutableMapOf<KtExpression, JsExpression>()
         for ((index, valueArg) in fakeCall.valueArguments.withIndex()) {
             val paramName = JsScope.declareTemporaryName(descriptor.valueParameters[index].name.asString())
             function.parameters += JsParameter(paramName)
-            aliases[valueArg.getArgumentExpression()!!] = paramName.makeRef()
+            val paramRef = paramName.makeRef()
+            paramRef.type = context.currentModule.builtIns.anyType
+            val type = functionDescriptor.valueParameters[index].type
+            aliases[valueArg.getArgumentExpression()!!] = TranslationUtils.coerce(context, paramRef, type)
         }
         val functionContext = context.innerBlock(function.body).innerContextWithAliasesForExpressions(aliases)
         val invocation = CallTranslator.translate(functionContext, fakeResolvedCall, receiverParam)
-        function.body.statements += JsReturn(invocation)
+        function.body.statements += JsReturn(TranslationUtils.coerce(context, invocation, context.currentModule.builtIns.anyType))
 
         val rawCallableRef = bindIfNecessary(function, receiver)
         return wrapFunctionCallableRef(expression.callableReference.getReferencedName(), rawCallableRef)

js/js.translator/src/org/jetbrains/kotlin/js/translate/reference/ReferenceTranslator.java

@@ -17,7 +17,10 @@
 package org.jetbrains.kotlin.js.translate.reference;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.*;
+import org.jetbrains.kotlin.descriptors.impl.AnonymousFunctionDescriptor;
 import org.jetbrains.kotlin.js.backend.ast.JsExpression;
 import org.jetbrains.kotlin.js.backend.ast.JsInvocation;
 import org.jetbrains.kotlin.js.backend.ast.JsName;
@@ -32,6 +35,7 @@ import org.jetbrains.kotlin.psi.KtExpression;
 import org.jetbrains.kotlin.psi.KtQualifiedExpression;
 import org.jetbrains.kotlin.psi.KtSimpleNameExpression;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
+import org.jetbrains.kotlin.types.KotlinType;
 
 import static org.jetbrains.kotlin.js.translate.utils.BindingUtils.getDescriptorForReferenceExpression;
 import static org.jetbrains.kotlin.js.translate.utils.PsiUtils.getSelectorAsSimpleName;
@@ -49,6 +53,41 @@ public final class ReferenceTranslator {
 
     @NotNull
     public static JsExpression translateAsValueReference(@NotNull DeclarationDescriptor descriptor, @NotNull TranslationContext context) {
+        JsExpression result = translateAsValueReferenceWithoutType(descriptor, context);
+        MetadataProperties.setType(result, getType(descriptor));
+        if (descriptor instanceof ClassDescriptor) {
+            if (KotlinBuiltIns.isUnit(((ClassDescriptor) descriptor).getDefaultType())) {
+                MetadataProperties.setUnit(result, true);
+                MetadataProperties.setSideEffects(result, SideEffectKind.PURE);
+                MetadataProperties.setSynthetic(result, true);
+            }
+        }
+        return result;
+    }
+
+    @Nullable
+    private static KotlinType getType(@NotNull DeclarationDescriptor descriptor) {
+        if (descriptor instanceof ClassDescriptor) {
+            return ((ClassDescriptor) descriptor).getDefaultType();
+        }
+        else if (descriptor instanceof CallableDescriptor) {
+            if (descriptor instanceof ValueParameterDescriptor) {
+                ValueParameterDescriptor parameter = (ValueParameterDescriptor) descriptor;
+                if (parameter.getContainingDeclaration() instanceof AnonymousFunctionDescriptor) {
+                    return DescriptorUtils.getContainingModule(descriptor).getBuiltIns().getAnyType();
+                }
+            }
+            return ((CallableDescriptor) descriptor).getReturnType();
+        }
+
+        return null;
+    }
+
+    @NotNull
+    private static JsExpression translateAsValueReferenceWithoutType(
+            @NotNull DeclarationDescriptor descriptor,
+            @NotNull TranslationContext context
+    ) {
         if (AnnotationsUtils.isNativeObject(descriptor) || AnnotationsUtils.isLibraryObject(descriptor)) {
             return context.getInnerReference(descriptor);
         }

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/FunctionBodyTranslator.java

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.js.translate.utils;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
+import org.jetbrains.kotlin.descriptors.ClassDescriptor;
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor;
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor;
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor;
@@ -31,6 +32,7 @@ import org.jetbrains.kotlin.js.translate.expression.LocalFunctionCollector;
 import org.jetbrains.kotlin.js.translate.general.AbstractTranslator;
 import org.jetbrains.kotlin.js.translate.general.Translation;
 import org.jetbrains.kotlin.js.translate.reference.ReferenceTranslator;
+import org.jetbrains.kotlin.psi.KtBlockExpression;
 import org.jetbrains.kotlin.psi.KtDeclarationWithBody;
 import org.jetbrains.kotlin.psi.KtExpression;
 import org.jetbrains.kotlin.resolve.source.KotlinSourceElementKt;
@@ -120,6 +122,16 @@ public final class FunctionBodyTranslator extends AbstractTranslator {
 
         JsNode jsBody = Translation.translateExpression(jetBodyExpression, context(), jsBlock);
         jsBlock.getStatements().addAll(mayBeWrapWithReturn(jsBody).getStatements());
+
+        if (jetBodyExpression instanceof KtBlockExpression &&
+            descriptor.getReturnType() != null && KotlinBuiltIns.isUnit(descriptor.getReturnType()) &&
+            !KotlinBuiltIns.isUnit(TranslationUtils.getReturnTypeForCoercion(descriptor))) {
+            ClassDescriptor unit = context().getCurrentModule().getBuiltIns().getUnit();
+            JsReturn jsReturn = new JsReturn(ReferenceTranslator.translateAsValueReference(unit, context()));
+            jsReturn.setSource(UtilsKt.getFinalElement(declaration));
+            jsBlock.getStatements().add(jsReturn);
+        }
+
         return jsBlock;
     }
 
@@ -145,12 +157,8 @@ public final class FunctionBodyTranslator extends AbstractTranslator {
             }
 
             assert declaration.getBodyExpression() != null;
-            assert descriptor.getReturnType() != null;
+            KotlinType returnType = TranslationUtils.getReturnTypeForCoercion(descriptor);
-            KotlinType bodyType = context().bindingContext().getType(declaration.getBodyExpression());
+            node = TranslationUtils.coerce(context(), (JsExpression) node, returnType);
-            if (bodyType == null && KotlinBuiltIns.isCharOrNullableChar(descriptor.getReturnType()) ||
-                bodyType != null && KotlinBuiltIns.isCharOrNullableChar(bodyType) && TranslationUtils.shouldBoxReturnValue(descriptor)) {
-                node = TranslationUtils.charToBoxedChar(context(), (JsExpression) node);
-            }
 
             JsReturn jsReturn = new JsReturn((JsExpression) node);
             jsReturn.setSource(declaration.getBodyExpression());

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/TranslationUtils.java

@@ -19,12 +19,15 @@ package org.jetbrains.kotlin.js.translate.utils;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.builtins.FunctionTypesKt;
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.descriptors.*;
+import org.jetbrains.kotlin.descriptors.impl.AnonymousFunctionDescriptor;
 import org.jetbrains.kotlin.descriptors.impl.LocalVariableAccessorDescriptor;
 import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor;
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation;
 import org.jetbrains.kotlin.js.backend.ast.*;
+import org.jetbrains.kotlin.js.backend.ast.metadata.BoxingKind;
 import org.jetbrains.kotlin.js.backend.ast.metadata.MetadataProperties;
 import org.jetbrains.kotlin.js.backend.ast.metadata.SpecialFunction;
 import org.jetbrains.kotlin.js.translate.context.Namer;
@@ -43,11 +46,11 @@ import org.jetbrains.kotlin.resolve.DescriptorUtils;
 import org.jetbrains.kotlin.resolve.descriptorUtil.DescriptorUtilsKt;
 import org.jetbrains.kotlin.resolve.inline.InlineUtil;
 import org.jetbrains.kotlin.resolve.source.KotlinSourceElementKt;
+import org.jetbrains.kotlin.types.DynamicTypesKt;
 import org.jetbrains.kotlin.types.KotlinType;
-import org.jetbrains.kotlin.types.TypeUtils;
 
-import java.util.ArrayList;
+import java.util.*;
-import java.util.List;
+import java.util.stream.Collectors;
 
 import static org.jetbrains.kotlin.js.backend.ast.JsBinaryOperator.*;
 import static org.jetbrains.kotlin.js.translate.utils.BindingUtils.getCallableDescriptorForOperationExpression;
@@ -186,7 +189,11 @@ public final class TranslationUtils {
         else {
             receiver = context.getDispatchReceiver(JsDescriptorUtils.getReceiverParameterForDeclaration(containingDescriptor));
         }
-        return new JsNameRef(backingFieldName, receiver);
+
+        JsNameRef result = new JsNameRef(backingFieldName, receiver);
+        MetadataProperties.setType(result, getReturnTypeForCoercion(descriptor));
+
+        return result;
     }
 
     @NotNull
@@ -205,10 +212,9 @@ public final class TranslationUtils {
         if (initializer != null) {
             jsInitExpression = Translation.translateAsExpression(initializer, context);
 
-            KotlinType propertyType = BindingContextUtils.getNotNull(context.bindingContext(), BindingContext.VARIABLE, declaration).getType();
+            KotlinType propertyType = BindingContextUtils.getNotNull(
-            KotlinType initType = context.bindingContext().getType(initializer);
+                    context.bindingContext(), BindingContext.VARIABLE, declaration).getType();
-
+            jsInitExpression = coerce(context, jsInitExpression, propertyType);
-            jsInitExpression = boxCastIfNeeded(context, jsInitExpression, initType, propertyType);
         }
         return jsInitExpression;
     }
@@ -394,61 +400,139 @@ public final class TranslationUtils {
                ModalityKt.isOverridable(descriptor);
     }
 
-    private static boolean overridesReturnAny(CallableDescriptor c) {
+    @NotNull
-        KotlinType returnType = c.getOriginal().getReturnType();
+    public static KotlinType getReturnTypeForCoercion(@NotNull CallableDescriptor descriptor) {
-        assert returnType != null;
+        descriptor = descriptor.getOriginal();
-        if (KotlinBuiltIns.isAnyOrNullableAny(returnType) || TypeUtils.isTypeParameter(returnType)) return true;
+
-        for (CallableDescriptor o : c.getOverriddenDescriptors()) {
+        if (FunctionTypesKt.getFunctionalClassKind(descriptor) != null || descriptor instanceof AnonymousFunctionDescriptor) {
-            if (overridesReturnAny(o)) return true;
+            return DescriptorUtils.getContainingModule(descriptor).getBuiltIns().getAnyType();
         }
-        return false;
-    }
 
-
+        Collection<? extends CallableDescriptor> overridden = descriptor.getOverriddenDescriptors();
-    public static boolean shouldBoxReturnValue(CallableDescriptor c) {
+        if (overridden.isEmpty()) {
-        return overridesReturnAny(c) || c instanceof CallableMemberDescriptor && ModalityKt.isOverridable((CallableMemberDescriptor)c);
+            return descriptor.getReturnType() != null ?
-    }
+                   descriptor.getReturnType() :
-
+                   DescriptorUtils.getContainingModule(descriptor).getBuiltIns().getAnyType();
-    @NotNull
-    public static JsExpression boxCastIfNeeded(
-            @NotNull TranslationContext context,
-            @NotNull JsExpression e,
-            @Nullable KotlinType castFrom, @Nullable KotlinType castTo
-    ) {
-        if (castFrom != null && KotlinBuiltIns.isCharOrNullableChar(castFrom) &&
-            castTo != null && !KotlinBuiltIns.isCharOrNullableChar(castTo)
-        ) {
-            return charToBoxedChar(context, e);
         }
-        return e;
+
+        Set<KotlinType> typesFromOverriddenCallables = overridden.stream()
+                .map(TranslationUtils::getReturnTypeForCoercion)
+                .collect(Collectors.toSet());
+        return typesFromOverriddenCallables.size() == 1
+               ? typesFromOverriddenCallables.iterator().next()
+               : DescriptorUtils.getContainingModule(descriptor).getBuiltIns().getAnyType();
     }
 
     @NotNull
-    public static JsExpression charToBoxedChar(@NotNull TranslationContext context, @NotNull JsExpression expression) {
+    public static KotlinType getDispatchReceiverTypeForCoercion(@NotNull CallableDescriptor descriptor) {
-        JsInvocation invocation = invokeSpecialFunction(context, SpecialFunction.TO_BOXED_CHAR, unnestBoxing(expression));
+        descriptor = descriptor.getOriginal();
-        invocation.setSource(expression.getSource());
+        if (descriptor.getDispatchReceiverParameter() == null) {
-        return withBoxingMetadata(invocation);
+            throw new IllegalArgumentException("This method can only be used for class members; " +
+                                               "given descriptor is not a member of a class " + descriptor);
+        }
+
+        Collection<? extends CallableDescriptor> overridden = descriptor.getOverriddenDescriptors();
+        if (overridden.isEmpty()) {
+            return descriptor.getDispatchReceiverParameter().getType();
+        }
+
+        Set<KotlinType> typesFromOverriddenCallables = overridden.stream()
+                .map(TranslationUtils::getDispatchReceiverTypeForCoercion)
+                .collect(Collectors.toSet());
+        return typesFromOverriddenCallables.size() == 1
+               ? typesFromOverriddenCallables.iterator().next()
+               : DescriptorUtils.getContainingModule(descriptor).getBuiltIns().getAnyType();
     }
 
     @NotNull
-    public static JsExpression boxedCharToChar(@NotNull TranslationContext context, @NotNull JsExpression expression) {
+    public static JsExpression coerce(@NotNull TranslationContext context, @NotNull JsExpression value, @NotNull KotlinType to) {
-        JsInvocation invocation = invokeSpecialFunction(context, SpecialFunction.UNBOX_CHAR, unnestBoxing(expression));
+        if (DynamicTypesKt.isDynamic(to)) return value;
-        invocation.setSource(expression.getSource());
+
-        return withBoxingMetadata(invocation);
+        KotlinType from = MetadataProperties.getType(value);
+        if (from == null) {
+            from = context.getCurrentModule().getBuiltIns().getAnyType();
+        }
+
+        if (from.equals(to)) return value;
+
+        if (KotlinBuiltIns.isCharOrNullableChar(to)) {
+            if (!KotlinBuiltIns.isCharOrNullableChar(from) && !(value instanceof JsNullLiteral)) {
+                value = boxedCharToChar(context, value);
+            }
+        }
+        else if (KotlinBuiltIns.isUnit(to)) {
+            if (!KotlinBuiltIns.isUnit(from)) {
+                value = unitToVoid(value);
+            }
+        }
+        else if (KotlinBuiltIns.isCharOrNullableChar(from)) {
+            if (!KotlinBuiltIns.isCharOrNullableChar(to) && !(value instanceof JsNullLiteral)) {
+                value = charToBoxedChar(context, value);
+            }
+        }
+        else if (KotlinBuiltIns.isUnit(from)) {
+            if (!KotlinBuiltIns.isUnit(to) && !MetadataProperties.isUnit(value)) {
+                ClassDescriptor unit = context.getCurrentModule().getBuiltIns().getUnit();
+                JsExpression unitRef = ReferenceTranslator.translateAsValueReference(unit, context);
+                value = JsAstUtils.newSequence(Arrays.asList(value, unitRef));
+            }
+        }
+
+        MetadataProperties.setType(value, to);
+        return value;
     }
 
     @NotNull
-    private static JsExpression unnestBoxing(@NotNull JsExpression expression) {
+    private static JsExpression unitToVoid(@NotNull JsExpression expression) {
-        if (expression instanceof JsInvocation && MetadataProperties.getBoxing((JsInvocation) expression)) {
+        if (expression instanceof JsBinaryOperation) {
-            return ((JsInvocation) expression).getArguments().get(0);
+            JsBinaryOperation binary = (JsBinaryOperation) expression;
+            if (binary.getOperator() == JsBinaryOperator.COMMA && MetadataProperties.isUnit(binary.getArg2())) {
+                return binary.getArg1();
+            }
         }
         return expression;
     }
 
     @NotNull
-    private static JsInvocation withBoxingMetadata(@NotNull JsInvocation call) {
+    public static JsExpression charToBoxedChar(@NotNull TranslationContext context, @NotNull JsExpression expression) {
-        MetadataProperties.setBoxing(call, true);
+        if (expression instanceof JsInvocation) {
-        return call;
+            JsInvocation invocation = (JsInvocation) expression;
+            BoxingKind existingKind = MetadataProperties.getBoxing(invocation);
+            switch (existingKind) {
+                case UNBOXING:
+                    return invocation.getArguments().get(0);
+                case BOXING:
+                    return expression;
+                case NONE:
+                    break;
+            }
+        }
+
+        JsInvocation result = invokeSpecialFunction(context, SpecialFunction.TO_BOXED_CHAR, expression);
+        result.setSource(expression.getSource());
+        MetadataProperties.setBoxing(result, BoxingKind.BOXING);
+        return result;
+    }
+
+    @NotNull
+    private static JsExpression boxedCharToChar(@NotNull TranslationContext context, @NotNull JsExpression expression) {
+        if (expression instanceof JsInvocation) {
+            JsInvocation invocation = (JsInvocation) expression;
+            BoxingKind existingKind = MetadataProperties.getBoxing(invocation);
+            switch (existingKind) {
+                case BOXING:
+                    return invocation.getArguments().get(0);
+                case UNBOXING:
+                    return expression;
+                case NONE:
+                    break;
+            }
+        }
+
+        JsInvocation result = invokeSpecialFunction(context, SpecialFunction.UNBOX_CHAR, expression);
+        result.setSource(expression.getSource());
+        MetadataProperties.setBoxing(result, BoxingKind.UNBOXING);
+        return result;
     }
 
     @NotNull

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/mutator/CoercionMutator.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2017 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.
+ */
+
+package org.jetbrains.kotlin.js.translate.utils.mutator;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.kotlin.js.backend.ast.JsExpression;
+import org.jetbrains.kotlin.js.backend.ast.JsNode;
+import org.jetbrains.kotlin.js.translate.context.TranslationContext;
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils;
+import org.jetbrains.kotlin.types.KotlinType;
+
+public class CoercionMutator implements Mutator {
+    private final KotlinType targetType;
+    private final TranslationContext context;
+
+    public CoercionMutator(@NotNull KotlinType targetType, @NotNull TranslationContext context) {
+        this.targetType = targetType;
+        this.context = context;
+    }
+
+    @NotNull
+    @Override
+    public JsNode mutate(@NotNull JsNode node) {
+        if (node instanceof JsExpression) {
+            return TranslationUtils.coerce(context, (JsExpression) node, targetType);
+        }
+
+        return node;
+    }
+}

js/js.translator/testData/box/char/charEquals.kt

@@ -9,5 +9,15 @@ fun box(): String {
     assertEquals(false, 'A'== 'B')
     assertEquals(false, ('A' as Any) == (65 as Any))
 
+    assertTrue(bar('Q'))
+    assertFalse(bar('W'))
+
+    assertTrue(baz('Q'))
+    assertFalse(baz('W'))
+
     return "OK"
 }
+
+fun bar(x: Char) = x.equals('Q')
+
+fun baz(x: Any) = x.equals('Q')

js/js.translator/testData/box/coercion/classProperty.kt

@@ -0,0 +1,18 @@
+// EXPECTED_REACHABLE_NODES: 1004
+class A {
+    var log = ""
+
+    fun foo() {
+        log += "foo()"
+    }
+
+    val bar: Any = foo()
+}
+
+fun box(): String {
+    val a = A()
+    if (a.bar != Unit) return "fail1: ${a.bar}"
+    if (a.log != "foo()") return "fail2: ${a.log}"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/derivedFunctionReturningChar.kt

@@ -0,0 +1,17 @@
+// EXPECTED_REACHABLE_NODES: 1006
+abstract class A<out T> {
+    abstract fun foo(): T
+}
+
+class B() : A<Char>() {
+    override fun foo() = 'Q'
+}
+
+private fun typeOf(x: dynamic) = js("typeof x")
+
+fun box(): String {
+    val a: A<Any> = B()
+    if (typeOf(a.foo()) != "object") return "fail1"
+    if (typeOf(B().foo()) != "number") return "fail2"
+    return "OK"
+}

js/js.translator/testData/box/coercion/derivedFunctionReturningUnit.kt

@@ -0,0 +1,20 @@
+// EXPECTED_REACHABLE_NODES: 1012
+var log = ""
+
+abstract class A<out T> {
+    abstract fun foo(): T
+}
+
+class B() : A<Unit>() {
+    override fun foo() {
+        log += "B.foo()"
+    }
+}
+
+fun box(): String {
+    val a: A<Any> = B()
+    if (a.foo() != Unit) return "fail1"
+    if (log != "B.foo()") return "fail2"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/destructuringToUnit.kt

@@ -0,0 +1,20 @@
+// EXPECTED_REACHABLE_NODES: 1006
+var log = ""
+
+class A {
+    operator fun component1() {
+        log += "A.component1()"
+    }
+
+    operator fun component2() = 23
+}
+
+fun box(): String {
+    val (x: Any, y) = A()
+
+    if (x != Unit) return "fail1: $x"
+    if (y != 23) return "fail2: $y"
+    if (log != "A.component1()") return "fail3: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/extensionReceiver.kt

@@ -0,0 +1,14 @@
+// EXPECTED_REACHABLE_NODES: 996
+fun box(): String {
+    val a = 'Q'.foo()
+    if (a != "number") return "fail1: $a"
+
+    val b = 'W'.bar()
+    if (b != "object") return "fail2: $b"
+
+    return "OK"
+}
+
+fun Char.foo() = jsTypeOf(this.asDynamic())
+
+fun Any.bar() = jsTypeOf(this.asDynamic())

js/js.translator/testData/box/coercion/ifWithUnit.kt

@@ -0,0 +1,19 @@
+// EXPECTED_REACHABLE_NODES: 1005
+var log = ""
+
+fun foo() {
+    log += "foo()"
+}
+
+fun test(x: Int) = if (x < 10) foo() else 55
+
+fun box(): String {
+    val a = test(20)
+    if (a !is Int) return "fail1: $a"
+
+    val b = test(5)
+    if (b !is Unit) return "fail2: $b"
+    if (log != "foo()") return "fail3: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/inlineFunReturningUnit.kt

@@ -0,0 +1,12 @@
+// EXPECTED_REACHABLE_NODES: 1000
+inline fun foo(i : Int) = if (i % 2 == 0) {} else i
+
+fun box(): String {
+    val a = foo(1)
+    if (a != 1) return "fail1: $a"
+
+    val b = foo(2)
+    if (b != Unit) return "fail2: $b"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/lambdaParameters.kt

@@ -0,0 +1,22 @@
+// EXPECTED_REACHABLE_NODES: 997
+// CHECK_NOT_CALLED_IN_SCOPE: function=toBoxedChar scope=box$lambda
+// CHECK_CALLED_IN_SCOPE: function=unboxChar scope=box$lambda
+// CHECK_CALLED_IN_SCOPE: function=toBoxedChar scope=box
+// CHECK_NOT_CALLED_IN_SCOPE: function=unboxChar scope=box
+
+fun <T> bar(x: T, y: (T) -> Boolean): Boolean = y(x) && jsTypeOf(x.asDynamic()) != "number"
+
+fun typeOf(x: dynamic) = js("typeof x")
+
+fun box(): String {
+    val f = { x: Char ->
+        val a: Char = x
+        val b: Any = x
+        typeOf(a) == "number" && typeOf(b) == "object"
+    }
+
+    if (!f('Q')) return "fail1"
+    if (!bar('W', f)) return "fail2"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/loopOverUnits.kt

@@ -0,0 +1,25 @@
+// EXPECTED_REACHABLE_NODES: 1009
+class A {
+    operator fun iterator() = B()
+}
+
+class B() {
+    private var count = 0
+
+    operator fun next() {
+        count++
+    }
+
+    operator fun hasNext() = count < 5
+}
+
+fun box(): String {
+    var i = 0
+    for (x: Any in A()) {
+        if (x != Unit) return "fail1: $x"
+        i++
+    }
+    if (i != 5) return "fail2: $i"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/receiverSmartCast.kt

@@ -0,0 +1,32 @@
+// EXPECTED_REACHABLE_NODES: 997
+fun foo(x: Any): String {
+    return when (x) {
+        is Char -> "char: ${x.toInt()}"
+        else -> "other: $x"
+    }
+}
+
+fun bar(x: Any): String {
+    return when (x) {
+        is Char -> "char: ${x.baz()}"
+        else -> "other: $x"
+    }
+}
+
+fun Char.baz(): Boolean = jsTypeOf(asDynamic()) == "number"
+
+fun box(): String {
+    val a = foo('0')
+    if (a != "char: 48") return "fail1: $a"
+
+    val b = foo(23)
+    if (b != "other: 23") return "fail2: $b"
+
+    val c = bar('0')
+    if (c != "char: true") return "fail3: $c"
+
+    val d = bar(23)
+    if (d != "other: 23") return "fail4: $d"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/safeCallLetReturningUnit.kt

@@ -0,0 +1,19 @@
+// EXPECTED_REACHABLE_NODES: 1004
+var log = ""
+
+fun test(param: Any?) {
+    param?.let {
+        log += "test($param);"
+    } ?: run {
+        log += "test-null;"
+    }
+}
+
+fun box(): String {
+    test(null)
+    test(23)
+
+    if (log != "test-null;test(23);") return "fail: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/topLevelProperty.kt

@@ -0,0 +1,15 @@
+// EXPECTED_REACHABLE_NODES: 1003
+var log = ""
+
+fun foo() {
+    log += "foo()"
+}
+
+val bar: Any = foo()
+
+fun box(): String {
+    if (bar != Unit) return "fail1: $bar"
+    if (log != "foo()") return "fail2: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/tryWithEmptyCatch.kt

@@ -0,0 +1,19 @@
+// EXPECTED_REACHABLE_NODES: 1004
+fun test(x: Int): Any {
+    return try {
+        if (x % 2 == 0) throw RuntimeException()
+        x
+    }
+    catch (e: RuntimeException) {
+    }
+}
+
+fun box(): String {
+    val a = test(1)
+    if (a != 1) return "fail1: $a"
+
+    val b = test(2)
+    if (b != Unit) return "fail2: $b"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/unitAsExtensionReceiver.kt

@@ -0,0 +1,17 @@
+// EXPECTED_REACHABLE_NODES: 1004
+var log = ""
+
+fun foo() {
+    log += "foo"
+}
+
+fun Unit.bar() = jsTypeOf(this.asDynamic()) == "undefined"
+
+fun Any.baz() = jsTypeOf(this.asDynamic()) == "object"
+
+fun box(): String {
+    if (!foo().bar()) return "fail1"
+    if (!foo().baz()) return "fail2"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/unitIsAs.kt

@@ -0,0 +1,14 @@
+// EXPECTED_REACHABLE_NODES: 1002
+var log = ""
+
+fun foo(): Unit {
+    log += "foo();"
+}
+
+fun box(): String {
+    if (foo() !is Any) return "fail1"
+    if (foo() as Any != Unit) return "fail2"
+    if (log != "foo();foo();") return "fail3: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/unitSafeCall.kt

@@ -0,0 +1,14 @@
+// EXPECTED_REACHABLE_NODES: 1004
+class C {
+    fun foo() {}
+}
+
+fun box(): String {
+    val a: C? = C()
+    val b: C? = null
+
+    if (a?.foo() != Unit) return "fail1: ${a?.foo()}"
+    if (b?.foo() != null) return "fail2: ${b?.foo()}"
+
+    return "OK"
+}

js/js.translator/testData/box/coercion/whenWithUnit.kt

@@ -0,0 +1,22 @@
+// EXPECTED_REACHABLE_NODES: 1005
+var log = ""
+
+fun foo() {
+    log += "foo()"
+}
+
+fun test(x: Int) = when (x) {
+    in 0..10 -> foo()
+    else -> 55
+}
+
+fun box(): String {
+    val a = test(20)
+    if (a !is Int) return "fail1: $a"
+
+    val b = test(5)
+    if (b !is Unit) return "fail2: $b"
+    if (log != "foo()") return "fail3: $log"
+
+    return "OK"
+}

js/js.translator/testData/box/nameClashes/propertyAndNativeMethod.kt

@@ -3,7 +3,7 @@
 // FILE: lib.kt
 package lib
 
-external fun bar()
+external fun bar(): Int
 
 val bar = 32
 

js/js.translator/testData/box/standardClasses/charArrayGetSet.kt

@@ -0,0 +1,26 @@
+// EXPECTED_REACHABLE_NODES: 997
+fun box(): String {
+    val a = CharArray(1)
+    val aType = jsTypeOf(a.asDynamic()[0])
+    if (aType != "number") return "fail1: $aType"
+
+    a[0] = 'Q'
+    val aType2 = jsTypeOf(a.asDynamic()[0])
+    if (aType2 != "number") return "fail2: $aType2"
+
+    val aType3 = jsTypeOf(a[0].asDynamic())
+    if (aType3 != "number") return "fail3: $aType3"
+
+    val b = Array<Char>(1) { 'Q' }
+    val bType = jsTypeOf(b.asDynamic()[0])
+    if (bType != "object") return "fail4: $bType"
+
+    b[0] = 'W'
+    val bType2 = jsTypeOf(b.asDynamic()[0])
+    if (bType2 != "object") return "fail5: $bType2"
+
+    val bType3 = jsTypeOf(b[0].asDynamic())
+    if (bType3 != "number") return "fail6: $bType3"
+
+    return "OK"
+}

js/js.translator/testData/lineNumbers/charBoxing.kt

@@ -1,20 +0,0 @@
-var log = ""
-
-inline fun String.foo(a: String): Int {
-    log += "foo1"
-    return asDynamic().indexOf(a)
-}
-
-inline fun String.foo(a: Char): Int {
-    log += "foo2"
-    return indexOf(a.toString())
-}
-
-fun bar(a: String, b: Char, x: Int) {
-    log += if (x > 0)
-        23
-    else
-        a.foo(b)
-}
-
-// LINES: 6 4 4 5 5 8 8 8 8 8 8 8 11 9 9 10 10 8 8 8 8 18 14 14 14 14 14 15 17 17 9 9 14 10 17 10 14 14 * 1 * 1

js/js.translator/testData/lineNumbers/destructuring.kt

@@ -27,4 +27,4 @@ fun bar(f: (Pair<String, String>) -> Unit) {
 }
 
 
-// LINES: 22 16 16 17 18 20 20 21 21 23 9 9 9 9 4 9 9 9 5 5 6 7 11 11 12 12 15 15 27 26 26 * 1 * 1
+// LINES: 22 16 16 17 18 20 20 21 21 22 22 23 9 9 9 9 4 9 9 9 5 5 6 7 11 11 12 12 15 15 27 26 26 * 1 * 1

js/js.translator/testData/lineNumbers/destructuringInline.kt

@@ -32,4 +32,4 @@ inline operator fun P.component1() = a
 
 inline operator fun P.component2() = b
 
-// LINES: 22 17 17 31 18 18 33 20 20 21 21 23 9 9 9 9 4 9 9 9 6 6 31 7 7 33 11 11 12 12 15 15 27 26 26 29 29 29 * 31 31 31 33 33 33 * 1 * 1
+// LINES: 22 17 17 31 18 18 33 20 20 21 21 22 22 23 9 9 9 9 4 9 9 9 6 6 31 7 7 33 11 11 12 12 15 15 27 26 26 29 29 29 * 31 31 31 33 33 33 * 1 * 1

js/js.translator/testData/lineNumbers/lambdaWithClosure.kt

@@ -4,4 +4,4 @@ fun foo(x: Int): () -> Unit = {
 
 fun bar() = 23
 
-// LINES: 1 1 1 2 2 1 1 1 5 5 5
+// LINES: 1 1 1 2 2 3 3 1 1 1 5 5 5