Avoid non-null assertions for inline classes based on nullable types

Note that there are more places where assertions for inline classes should refined:
  - lateinit vars
  - values that come from Java
  - type casts (interfaces to inline class type)

compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.protobuf.MessageLite;
 import org.jetbrains.kotlin.renderer.DescriptorRenderer;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
+import org.jetbrains.kotlin.resolve.InlineClassesUtilsKt;
 import org.jetbrains.kotlin.resolve.annotations.AnnotationUtilKt;
 import org.jetbrains.kotlin.resolve.inline.InlineUtil;
 import org.jetbrains.kotlin.resolve.jvm.JvmClassName;
@@ -683,7 +684,7 @@ public class AsmUtil {
             @NotNull String name
     ) {
         KotlinType type = parameter.getType();
-        if (isNullableType(type)) return;
+        if (isNullableType(type) || InlineClassesUtilsKt.isNullableUnderlyingType(type)) return;
 
         int index = frameMap.getIndex(parameter);
         Type asmType = typeMapper.mapType(type);

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/RuntimeAssertions.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
+ * Copyright 2000-2018 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.
- * 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.resolve.jvm
@@ -30,6 +19,7 @@ import org.jetbrains.kotlin.resolve.calls.checkers.CallChecker
 import org.jetbrains.kotlin.resolve.calls.checkers.CallCheckerContext
 import org.jetbrains.kotlin.resolve.calls.context.ResolutionContext
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
+import org.jetbrains.kotlin.resolve.isNullableUnderlyingType
 import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
 import org.jetbrains.kotlin.types.*
@@ -62,7 +52,12 @@ class RuntimeAssertionInfo(val needNotNullAssertion: Boolean, val message: Strin
                 // Cases when nullability assertion needed: T! -> T, T$ -> T
 
                 // Expected type either T?, T! or T$
-                if (TypeUtils.isNullableType(expectedType) || expectedType.hasEnhancedNullability()) return false
+                if (TypeUtils.isNullableType(expectedType) ||
+                    expectedType.hasEnhancedNullability() ||
+                    expectedType.isNullableUnderlyingType()
+                ) {
+                    return false
+                }
 
                 // Expression type is not nullable and not enhanced (neither T?, T! or T$)
                 val isExpressionTypeNullable = TypeUtils.isNullableType(expressionType)

compiler/testData/codegen/box/inlineClasses/noAssertionsOnInlineClassBasedOnNullableType.kt

@@ -0,0 +1,38 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Result<T>(val a: Any?)
+
+fun resultOfIntToResultOfInt(r: Result<Int>): Result<Int> {
+    return r
+}
+
+fun <T> idResult(r: Result<T>): Result<T> = r
+
+fun Result<Int>.extension(): Result<Int> = this
+
+fun box(): String {
+    val r = Result<Int>(null)
+
+    resultOfIntToResultOfInt(r)
+    resultOfIntToResultOfInt(Result<Int>(null))
+
+    val nonNull1 = resultOfIntToResultOfInt(r)
+    val nonNull2 = resultOfIntToResultOfInt(Result<Int>(null))
+
+    resultOfIntToResultOfInt(nonNull1)
+
+    if (nonNull1.a != null) return "fail"
+    if (nonNull2.a != null) return "fail"
+
+    if (resultOfIntToResultOfInt(r).a != null) return "fail"
+
+    idResult(Result<String>(null))
+
+    val id = idResult(r)
+    if (id.a != null) return "fail"
+
+    r.extension()
+    Result<Int>(null).extension()
+
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/inlineClasses/assertionsForParametersOfInlineClassTypes.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +InlineClasses
+
+inline class AsNonNullPrimitive(val i: Int)
+inline class AsNonNullReference(val s: String) // 2 assertions (constructor, box method)
+
+fun nonNullPrimitive(a: AsNonNullPrimitive) {}
+
+fun nonNullReference(b: AsNonNullReference) {} // assertion
+fun AsNonNullReference.nonNullReferenceExtension(b1: AsNonNullReference) {} // 2 assertions
+
+fun asNullablePrimitive(c: AsNonNullPrimitive?) {}
+fun asNullableReference(c: AsNonNullReference?) {}
+
+// 5 checkParameterIsNotNull

compiler/testData/codegen/bytecodeText/inlineClasses/noAssertionsForInlineClassesBasedOnNullableTypes.kt

@@ -0,0 +1,8 @@
+// !LANGUAGE: +InlineClasses
+
+inline class AsAny(val a: Any?)
+
+fun asNotNullAny(a: AsAny) {}
+fun AsAny.asNotNullAnyExtension(b: AsAny): AsAny = this
+
+// 0 checkParameterIsNotNull

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -10653,6 +10653,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("noAssertionsOnInlineClassBasedOnNullableType.kt")
+        public void testNoAssertionsOnInlineClassBasedOnNullableType() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/noAssertionsOnInlineClassBasedOnNullableType.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("passInlineClassAsVararg.kt")
         public void testPassInlineClassAsVararg() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/passInlineClassAsVararg.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -10653,6 +10653,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("noAssertionsOnInlineClassBasedOnNullableType.kt")
+        public void testNoAssertionsOnInlineClassBasedOnNullableType() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/noAssertionsOnInlineClassBasedOnNullableType.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("passInlineClassAsVararg.kt")
         public void testPassInlineClassAsVararg() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/passInlineClassAsVararg.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -1947,6 +1947,12 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             doTest(fileName);
         }
 
+        @TestMetadata("assertionsForParametersOfInlineClassTypes.kt")
+        public void testAssertionsForParametersOfInlineClassTypes() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inlineClasses/assertionsForParametersOfInlineClassTypes.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("boxInlineClassesOnPassingToVarargs.kt")
         public void testBoxInlineClassesOnPassingToVarargs() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inlineClasses/boxInlineClassesOnPassingToVarargs.kt");
@@ -2049,6 +2055,12 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             doTest(fileName);
         }
 
+        @TestMetadata("noAssertionsForInlineClassesBasedOnNullableTypes.kt")
+        public void testNoAssertionsForInlineClassesBasedOnNullableTypes() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inlineClasses/noAssertionsForInlineClassesBasedOnNullableTypes.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("passInlineClassesWithSpreadOperatorToVarargs.kt")
         public void testPassInlineClassesWithSpreadOperatorToVarargs() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inlineClasses/passInlineClassesWithSpreadOperatorToVarargs.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -10653,6 +10653,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             doTest(fileName);
         }
 
+        @TestMetadata("noAssertionsOnInlineClassBasedOnNullableType.kt")
+        public void testNoAssertionsOnInlineClassBasedOnNullableType() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/noAssertionsOnInlineClassBasedOnNullableType.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("passInlineClassAsVararg.kt")
         public void testPassInlineClassAsVararg() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/passInlineClassAsVararg.kt");

core/descriptors/src/org/jetbrains/kotlin/resolve/inlineClassesUtils.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 fun ClassDescriptor.underlyingRepresentation(): ValueParameterDescriptor? {
@@ -30,4 +31,11 @@ fun KotlinType.isInlineClassType(): Boolean = constructor.declarationDescriptor?
 fun KotlinType.substitutedUnderlyingType(): KotlinType? {
     val parameter = unsubstitutedUnderlyingParameter() ?: return null
     return memberScope.getContributedVariables(parameter.name, NoLookupLocation.FOR_ALREADY_TRACKED).singleOrNull()?.type
+}
+
+fun KotlinType.isNullableUnderlyingType(): Boolean {
+    if (!isInlineClassType()) return false
+    val underlyingType = unsubstitutedUnderlyingType() ?: return false
+
+    return TypeUtils.isNullableType(underlyingType)
 }

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

@@ -11715,6 +11715,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             doTest(fileName);
         }
 
+        @TestMetadata("noAssertionsOnInlineClassBasedOnNullableType.kt")
+        public void testNoAssertionsOnInlineClassBasedOnNullableType() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/noAssertionsOnInlineClassBasedOnNullableType.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("passInlineClassAsVararg.kt")
         public void testPassInlineClassAsVararg() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/inlineClasses/passInlineClassAsVararg.kt");