JS/RTTI: avoid possible side-effect for is-check on nullable type

#KT-7038 fixed

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

@@ -77,6 +77,18 @@ public class RttiTestGenerated extends AbstractRttiTest {
         doTest(fileName);
     }
 
+    @TestMetadata("sideEffectMethod.kt")
+    public void testSideEffectMethod() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/rtti/cases/sideEffectMethod.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("sideEffectProperty.kt")
+    public void testSideEffectProperty() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/rtti/cases/sideEffectProperty.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("stdlibEmptyListClass.kt")
     public void testStdlibEmptyListClass() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/rtti/cases/stdlibEmptyListClass.kt");

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

@@ -20,9 +20,7 @@ import com.google.dart.compiler.backend.js.ast.*
 import com.google.dart.compiler.backend.js.ast.metadata.TypeCheck
 import com.google.dart.compiler.backend.js.ast.metadata.typeCheck
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
-import org.jetbrains.kotlin.js.translate.utils.JsAstUtils.or
-import org.jetbrains.kotlin.js.translate.utils.JsAstUtils.typeOfIs
-import org.jetbrains.kotlin.js.translate.utils.TranslationUtils.isNullCheck
+import org.jetbrains.kotlin.js.translate.utils.JsAstUtils.*
 import java.util.*
 
 fun expandIsCalls(node: JsNode, context: TranslationContext) {
@@ -71,9 +69,16 @@ private class TypeCheckRewritingVisitor(private val context: TranslationContext)
             TypeCheck.INSTANCEOF ->
                 context.namer().isInstanceOf(argument, calleeArgument)
 
-            // Kotlin.orNull(calleeArgument)(argument) -> argument === null || calleeArgument(argument)
-            TypeCheck.OR_NULL ->
-                or(isNullCheck(argument), JsInvocation(calleeArgument, argument))
+            // Kotlin.orNull(calleeArgument)(argument) -> (tmp = argument) == null || calleeArgument(tmp)
+            TypeCheck.OR_NULL -> {
+                val currentScope = scopes.peek()
+                val tmp = currentScope.declareTemporary()
+                val statementContext = lastStatementLevelContext
+                statementContext.addPrevious(newVar(tmp, null))
+                val assignment = assignment(tmp.makeRef(), argument)
+                val tmpIsNull = TranslationUtils.isNullCheck(assignment)
+                or(tmpIsNull, JsInvocation(calleeArgument, tmp.makeRef()))
+            }
 
             else ->
                 null

js/js.translator/testData/rtti/cases/sideEffectMethod.kt

@@ -0,0 +1,21 @@
+package foo
+
+var counter = 0
+
+class A {
+    fun getCounter(): Any? =
+        when (counter++) {
+            0 -> "0"
+            1 -> null
+            else -> counter
+        }
+}
+
+fun box(): String {
+    assertEquals(false, A().getCounter() is Int?, "(1)")
+    assertEquals(true, A().getCounter() is Int?, "(2)")
+    assertEquals(true, A().getCounter() is Int?, "(3)")
+    assertEquals(3, counter)
+
+    return "OK"
+}

js/js.translator/testData/rtti/cases/sideEffectProperty.kt

@@ -0,0 +1,22 @@
+package foo
+
+var counter = 0
+
+class A {
+    val x: Any?
+        get() =
+            when (counter++) {
+                0 -> "0"
+                1 -> null
+                else -> counter
+            }
+}
+
+fun box(): String {
+    assertEquals(false, A().x is Int?, "(1)")
+    assertEquals(true, A().x is Int?, "(2)")
+    assertEquals(true, A().x is Int?, "(3)")
+    assertEquals(3, counter)
+
+    return "OK"
+}