[JS BE] Support val in when subject

#KT-25014 Fixed

compiler/testData/codegen/box/when/whenSubjectVariable/captureSubjectVariable.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
-// IGNORE_BACKEND: JS
 
 fun box(): String {
     var y: String = "OK"

compiler/testData/codegen/box/when/whenSubjectVariable/denseIntSwitchWithSubjectVariable.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
 // WITH_RUNTIME
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS_IR
 
 fun dense(x: Int): Int {
     return when (val xx = x) {

compiler/testData/codegen/box/when/whenSubjectVariable/equalityWithSubjectVariable.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
-// IGNORE_BACKEND: JS
 
 val x = 1
 

compiler/testData/codegen/box/when/whenSubjectVariable/ieee754Equality.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
-// IGNORE_BACKEND: JS
 
 val dz = -0.0
 val fz = -0.0f
@@ -29,5 +28,14 @@ fun box(): String {
         }
     }
 
+    testDoubleAsUpperBound(-0.0)
+
     return "OK"
-}
+}
+
+fun <T: Double> testDoubleAsUpperBound(v: T): Boolean {
+    return when (val a = v*v) {
+        0.0 -> true
+        else -> throw AssertionError()
+    }
+}

compiler/testData/codegen/box/when/whenSubjectVariable/ieee754EqualityWithSmartCast.kt

@@ -1,22 +1,32 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject +ProperIeee754Comparisons
 // IGNORE_BACKEND: JVM_IR
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS_IR
 
 val az: Any = -0.0
 val afz: Any = -0.0f
 
 fun box(): String {
-    when (val y = az) {
+    val y = az
+    when (y) {
         !is Double -> throw AssertionError()
         0.0 -> {}
         else -> throw AssertionError()
     }
-
-    when (val y = afz) {
+    val yy = afz
+    when (yy) {
         !is Float -> throw AssertionError()
         0.0 -> {}
         else -> throw AssertionError()
     }
 
+    testDoubleAsUpperBound(-0.0)
+
     return "OK"
-}
+}
+
+fun <T: Double> testDoubleAsUpperBound(v: T): Boolean {
+    return when (val a = v*v) {
+        0.0 -> true
+        else -> throw AssertionError()
+    }
+}

compiler/testData/codegen/box/when/whenSubjectVariable/isCheckOnSubjectVariable.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
-// IGNORE_BACKEND: JS
 
 val x: Any = 1
 

compiler/testData/codegen/box/when/whenSubjectVariable/sparseIntSwitchWithSubjectVariable.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
 // WITH_RUNTIME
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS_IR
 
 fun sparse(x: Int): Int {
     return when (val xx = (x % 4) * 100) {

compiler/testData/codegen/box/when/whenSubjectVariable/subjectExpressionIsEvaluatedOnce.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
-// IGNORE_BACKEND: JS
 
 var effectCount = 0
 

compiler/testData/codegen/box/when/whenSubjectVariable/whenByEnum.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
 // WITH_RUNTIME
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS_IR
 
 import kotlin.test.assertEquals
 

compiler/testData/codegen/box/when/whenSubjectVariable/whenByNullableEnum.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
 // WITH_RUNTIME
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS_IR
 
 import kotlin.test.assertEquals
 

compiler/testData/codegen/box/when/whenSubjectVariable/whenByString.kt

@@ -1,6 +1,5 @@
 // !LANGUAGE: +VariableDeclarationInWhenSubject
 // WITH_RUNTIME
-// IGNORE_BACKEND: JS
 
 import kotlin.test.assertEquals
 

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

@@ -1,17 +1,6 @@
 /*
- * 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.
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.js.translate.expression;
@@ -36,10 +25,7 @@ import org.jetbrains.kotlin.js.translate.intrinsic.functions.factories.TopLevelF
 import org.jetbrains.kotlin.js.translate.reference.ReferenceTranslator;
 import org.jetbrains.kotlin.js.translate.utils.*;
 import org.jetbrains.kotlin.name.Name;
-import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS;
-import org.jetbrains.kotlin.psi.KtExpression;
-import org.jetbrains.kotlin.psi.KtIsExpression;
-import org.jetbrains.kotlin.psi.KtTypeReference;
+import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
 import org.jetbrains.kotlin.resolve.checkers.PrimitiveNumericComparisonInfo;
 import org.jetbrains.kotlin.types.KotlinType;
@@ -270,31 +256,32 @@ public final class PatternTranslator extends AbstractTranslator {
 
     @NotNull
     public JsExpression translateExpressionPattern(
-            @NotNull KtExpression subjectExpression,
+            @NotNull KotlinType subjectType,
             @NotNull JsExpression expressionToMatch,
             @NotNull KtExpression patternExpression
     ) {
         PrimitiveNumericComparisonInfo ieeeInfo = UtilsKt.getPrimitiveNumericComparisonInfo(context(), patternExpression);
 
-        KotlinType subjectType, patternType;
+        KotlinType actualSubjectType;
+        KotlinType patternType;
         if (ieeeInfo != null) {
-            subjectType = ieeeInfo.getLeftType();
+            actualSubjectType = ieeeInfo.getLeftType();
             patternType = ieeeInfo.getRightType();
         } else {
-            subjectType = UtilsKt.getPrecisePrimitiveTypeNotNull(context(), subjectExpression);
+            actualSubjectType = UtilsKt.refineType(subjectType);
             patternType = UtilsKt.getPrecisePrimitiveTypeNotNull(context(), patternExpression);
         }
 
-        EqualityType matchEquality = equalityType(subjectType);
+        EqualityType matchEquality = equalityType(actualSubjectType);
         EqualityType patternEquality = equalityType(patternType);
 
-        JsExpression expressionToMatchAgainst = TranslationUtils.coerce(context(), translateExpressionForExpressionPattern(patternExpression), subjectType);
+        JsExpression expressionToMatchAgainst = TranslationUtils.coerce(context(), translateExpressionForExpressionPattern(patternExpression), actualSubjectType);
 
         if (matchEquality == EqualityType.PRIMITIVE && patternEquality == EqualityType.PRIMITIVE) {
             return equality(expressionToMatch, expressionToMatchAgainst);
         }
         else if (expressionToMatchAgainst instanceof JsNullLiteral) {
-            return TranslationUtils.nullCheck(subjectExpression, expressionToMatch, context(), false);
+            return TranslationUtils.nullCheck(actualSubjectType, expressionToMatch, context(), false);
         }
         else {
             return TopLevelFIF.KOTLIN_EQUALS.apply(expressionToMatch, Collections.singletonList(expressionToMatchAgainst), context());

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

@@ -1,17 +1,6 @@
 /*
- * 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.
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.js.translate.expression
@@ -19,6 +8,7 @@ package org.jetbrains.kotlin.js.translate.expression
 import org.jetbrains.kotlin.backend.common.CodegenUtil
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.config.languageVersionSettings
+import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.js.backend.ast.*
@@ -27,6 +17,7 @@ import org.jetbrains.kotlin.js.translate.context.TranslationContext
 import org.jetbrains.kotlin.js.translate.general.AbstractTranslator
 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.JsAstUtils.not
 import org.jetbrains.kotlin.js.translate.utils.mutator.CoercionMutator
@@ -49,6 +40,7 @@ private typealias EntryWithConstants = Pair<List<JsExpression>, KtWhenEntry>
 
 class WhenTranslator
 private constructor(private val whenExpression: KtWhenExpression, context: TranslationContext) : AbstractTranslator(context) {
+    private val subjectType: KotlinType?
     private val expressionToMatch: JsExpression?
     private val type: KotlinType?
     private val uniqueConstants = mutableSetOf<Any>()
@@ -63,8 +55,27 @@ private constructor(private val whenExpression: KtWhenExpression, context: Trans
         }
 
     init {
-        val subject = whenExpression.subjectExpression
-        expressionToMatch = if (subject != null) context.defineTemporary(Translation.translateAsExpression(subject, context)) else null
+        val subjectVariable = whenExpression.subjectVariable
+        val subjectExpression = whenExpression.subjectExpression
+
+        when {
+            subjectVariable != null -> {
+                val variable = Translation.translateAsStatement(subjectVariable, context) as JsVars
+                context.addStatementToCurrentBlock(variable)
+
+                val descriptor = BindingUtils.getDescriptorForElement(context.bindingContext(), subjectVariable) as? CallableDescriptor
+                subjectType = descriptor?.returnType
+                expressionToMatch = variable.vars.first().name.makeRef()
+            }
+            subjectExpression != null -> {
+                subjectType = bindingContext().getType(subjectExpression)
+                expressionToMatch = context.defineTemporary(Translation.translateAsExpression(subjectExpression, context))
+            }
+            else -> {
+                subjectType = null
+                expressionToMatch = null
+            }
+        }
 
         type = bindingContext().getType(whenExpression)
     }
@@ -123,8 +134,8 @@ private constructor(private val whenExpression: KtWhenExpression, context: Trans
     }
 
     private fun translateAsSwitch(fromIndex: Int): Pair<JsSwitch, Int>? {
+        val subjectType = subjectType ?: return null
         val ktSubject = whenExpression.subjectExpression ?: return null
-        val subjectType = bindingContext().getType(ktSubject) ?: return null
 
         val dataFlow = dataFlowValueFactory.createDataFlowValue(
                 ktSubject, subjectType, bindingContext(), context().declarationDescriptor ?: context().currentModule)
@@ -322,12 +333,11 @@ private constructor(private val whenExpression: KtWhenExpression, context: Trans
     private fun translateExpressionCondition(condition: KtWhenConditionWithExpression, context: TranslationContext): JsExpression {
         val patternExpression = condition.expression ?: error("Expression pattern should have an expression.")
 
-        val expressionToMatch = expressionToMatch
         val patternTranslator = Translation.patternTranslator(context)
         return if (expressionToMatch == null) {
             patternTranslator.translateExpressionForExpressionPattern(patternExpression)
         } else {
-            patternTranslator.translateExpressionPattern(whenExpression.subjectExpression!!, expressionToMatch, patternExpression)
+            patternTranslator.translateExpressionPattern(subjectType!!, expressionToMatch, patternExpression)
         }
     }
 

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

@@ -173,6 +173,16 @@ public final class TranslationUtils {
         return nullCheck(prepareForNullCheck(ktSubject, expressionToCheck, context), isNegated);
     }
 
+    @NotNull
+    public static JsBinaryOperation nullCheck(
+            @NotNull KotlinType expressionType,
+            @NotNull JsExpression expressionToCheck,
+            @NotNull TranslationContext context,
+            boolean isNegated
+    ) {
+        return nullCheck(coerce(context, expressionToCheck, TypeUtils.makeNullable(expressionType)), isNegated);
+    }
+
     @NotNull
     public static JsConditional notNullConditional(
             @NotNull JsExpression expression,

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/utils.kt

@@ -242,6 +242,9 @@ fun TranslationContext.createCoroutineResult(resolvedCall: ResolvedCall<*>): JsE
     }
 }
 
+fun KotlinType.refineType() =
+    TypeUtils.getAllSupertypes(this).find(KotlinBuiltIns::isPrimitiveTypeOrNullablePrimitiveType) ?: this
+
 /**
  * Tries to get precise statically known primitive type. Takes generic supertypes into account. Doesn't handle smart-casts.
  * This is needed to be compatible with JVM NaN behaviour:
@@ -256,7 +259,7 @@ fun TranslationContext.getPrecisePrimitiveType(expression: KtExpression): Kotlin
     val bindingContext = bindingContext()
     val ktType = bindingContext.getType(expression) ?: return null
 
-    return TypeUtils.getAllSupertypes(ktType).find(KotlinBuiltIns::isPrimitiveTypeOrNullablePrimitiveType) ?: ktType
+    return ktType.refineType()
 }
 
 fun TranslationContext.getPrecisePrimitiveTypeNotNull(expression: KtExpression): KotlinType {