[IR] Fix for https://youtrack.jetbrains.com/issue/KT-37057 + test

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/BuiltinOperatorLowering.kt

@@ -14,7 +14,6 @@ import org.jetbrains.kotlin.backend.common.lower.irNot
 import org.jetbrains.kotlin.backend.konan.*
 import org.jetbrains.kotlin.backend.konan.ir.containsNull
 import org.jetbrains.kotlin.backend.konan.ir.isSubtypeOf
-import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltinOperatorDescriptor
@@ -26,6 +25,7 @@ import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.makeNullable
 import org.jetbrains.kotlin.ir.builders.irGet
 import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.isNothing
@@ -39,7 +39,6 @@ import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
  */
 internal class BuiltinOperatorLowering(val context: Context) : FileLoweringPass, IrBuildingTransformer(context) {
 
-    private val builtIns = context.builtIns
     private val irBuiltins = context.irModule!!.irBuiltins
     private val symbols = context.ir.symbols
 
@@ -135,11 +134,7 @@ internal class BuiltinOperatorLowering(val context: Context) : FileLoweringPass,
         val equals = irClass.simpleFunctions()
                 .single { it.name.asString() == "equals" && it.valueParameters.size == 1 && it.overrides(anyEquals) }
 
-        // Note: this is not absolutely correct for inline class from other module
-        // since custom equals implementation can be added after compilation but before linking.
-        // TODO: reimplement after inline classes get properly designed `equals` operator.
-        // see https://youtrack.jetbrains.com/issue/KT-26354.
-        return equals.descriptor.kind == CallableMemberDescriptor.Kind.SYNTHESIZED
+        return equals.origin == IrDeclarationOrigin.GENERATED_INLINE_CLASS_MEMBER
     }
 
     fun IrBuilderWithScope.genInlineClassEquals(

backend.native/tests/build.gradle

@@ -3008,6 +3008,10 @@ task inlineClass0(type: KonanLocalTest) {
     source = "codegen/inlineClass/inlineClass0.kt"
 }
 
+task inlineClass_customEquals(type: KonanLocalTest) {
+    source = "codegen/inlineClass/customEquals.kt"
+}
+
 task deserialized_inline0(type: KonanLocalTest) {
     source = "serialization/deserialized_inline0.kt"
 }

backend.native/tests/codegen/inlineClass/customEquals.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+@file:Suppress("RESERVED_MEMBER_INSIDE_INLINE_CLASS")
+package codegen.inlineClass.customEquals
+
+import kotlin.test.*
+
+private inline class Z(val data: Int) {
+    override fun equals(other: Any?) = other is Z && data % 256 == other.data % 256
+}
+
+@Test fun runTest() {
+    assertTrue(Z(0) == Z(256))
+}