JS: fix inlining of callable references

compiler/testData/codegen/box/reflection/functions/simpleNames.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_REFLECT
 
 import kotlin.test.assertEquals

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

@@ -32,6 +32,8 @@ var JsName.descriptor: DeclarationDescriptor? by MetadataProperty(default = null
 // TODO: move this to module 'js.inliner' and change dependency on 'frontend' to dependency on 'descriptors'
 var JsInvocation.inlineStrategy: InlineStrategy? by MetadataProperty(default = null)
 
+var JsInvocation.isCallableReference by MetadataProperty(default = false)
+
 var JsInvocation.descriptor: CallableDescriptor? by MetadataProperty(default = null)
 
 var JsInvocation.psiElement: PsiElement? by MetadataProperty(default = null)

js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/RedundantStatementElimination.kt

@@ -190,6 +190,8 @@ class RedundantStatementElimination(private val root: JsFunction) {
 
             is JsObjectLiteral -> expression.propertyInitializers.flatMap { replace(it.labelExpr) + replace(it.valueExpr) }
 
+            is JsFunction -> if (expression.name == null) listOf() else listOf(expression)
+
             else -> listOf(expression)
         }
     }

js/js.inliner/src/org/jetbrains/kotlin/js/inline/context/FunctionContext.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.js.inline.context
 
 import org.jetbrains.kotlin.js.backend.ast.*
+import org.jetbrains.kotlin.js.backend.ast.metadata.isCallableReference
 import org.jetbrains.kotlin.js.backend.ast.metadata.descriptor
 import org.jetbrains.kotlin.js.inline.FunctionReader
 import org.jetbrains.kotlin.js.inline.util.*
@@ -91,7 +92,7 @@ abstract class FunctionContext(
         val qualifier = callQualifier.transitiveStaticRef
         return when (qualifier) {
             is JsInvocation -> {
-                getSimpleName(qualifier)?.let { simpleName ->
+                tryExtractCallableReference(qualifier) ?: getSimpleName(qualifier)?.let { simpleName ->
                     lookUpStaticFunction(simpleName)?.let { if (isFunctionCreator(it)) it else null }
                 }
             }
@@ -100,4 +101,12 @@ abstract class FunctionContext(
             else -> null
         }
     }
+
+    private fun tryExtractCallableReference(invocation: JsInvocation): JsFunction? {
+        if (invocation.isCallableReference) {
+            val arg = invocation.arguments[1]
+            if (arg is JsFunction) return arg
+        }
+        return null
+    }
 }

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

@@ -16694,13 +16694,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             @TestMetadata("simpleNames.kt")
             public void testSimpleNames() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/functions/simpleNames.kt");
-                try {
-                    doTest(fileName);
-                }
-                catch (Throwable ignore) {
-                    return;
-                }
-                throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+                doTest(fileName);
             }
         }
 

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

@@ -22,6 +22,9 @@ import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 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.translate.callTranslator.CallTranslator
 import org.jetbrains.kotlin.js.translate.context.Namer
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
@@ -226,7 +229,10 @@ object CallableReferenceTranslator {
         val nameLiteral = context.program().getStringLiteral(name)
         val invokeName = Namer.FUNCTION_CALLABLE_REF
         val invokeFun = JsNameRef(invokeName, Namer.kotlinObject())
+        invokeFun.sideEffects = SideEffectKind.PURE
         val invocation = JsInvocation(invokeFun, nameLiteral, function)
+        invocation.isCallableReference = true
+        invocation.sideEffects = SideEffectKind.PURE
         return invocation
     }
 }

js/js.translator/testData/box/inlineMultiModule/callableReference.kt

@@ -14,7 +14,7 @@ import utils.*
 
 // CHECK_CONTAINS_NO_CALLS: test except=imul
 
-internal fun multiplyBy2(x: Int): Int = x * 2
+internal inline fun multiplyBy2(x: Int): Int = x * 2
 
 internal fun test(x: Int): Int = apply(x, ::multiplyBy2)
 

js/js.translator/testData/box/inlineStdlib/callableRefToFunInCurrentModule.kt

@@ -3,7 +3,7 @@ package foo
 // CHECK_NOT_CALLED_IN_SCOPE: scope=test function=even
 // CHECK_NOT_CALLED_IN_SCOPE: scope=test function=filter_azvtw4$
 
-internal fun even(x: Int) = x % 2 == 0
+internal inline fun even(x: Int) = x % 2 == 0
 
 internal fun test(a: List<Int>) = a.filter(::even)