JVM: no nullability annotations for inline class '-impl' methods

Specialized generated methods for inline classes (toString-impl,
hashCode-impl, equals-impl, etc) are inaccessible from Java, and thus
don't require nullability annotations.

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

@@ -33,10 +33,7 @@ import org.jetbrains.kotlin.load.java.JvmAbi;
 import org.jetbrains.kotlin.load.java.SpecialBuiltinMembers;
 import org.jetbrains.kotlin.load.java.descriptors.JavaClassDescriptor;
 import org.jetbrains.kotlin.psi.*;
-import org.jetbrains.kotlin.resolve.BindingContext;
+import org.jetbrains.kotlin.resolve.*;
-import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils;
-import org.jetbrains.kotlin.resolve.DescriptorUtils;
-import org.jetbrains.kotlin.resolve.InlineClassesUtilsKt;
 import org.jetbrains.kotlin.resolve.annotations.AnnotationUtilKt;
 import org.jetbrains.kotlin.resolve.calls.util.UnderscoreUtilKt;
 import org.jetbrains.kotlin.resolve.constants.ArrayValue;
@@ -219,7 +216,9 @@ public class FunctionCodegen {
 
         recordMethodForFunctionIfAppropriate(functionDescriptor, asmMethod);
 
-        boolean skipNullabilityAnnotations = (flags & ACC_PRIVATE) != 0 || (flags & ACC_SYNTHETIC) != 0;
+        boolean skipNullabilityAnnotations =
+                (flags & ACC_PRIVATE) != 0 || (flags & ACC_SYNTHETIC) != 0 ||
+                InlineClassDescriptorResolver.isSpecializedEqualsMethod(functionDescriptor);
         generateMethodAnnotationsIfRequired(
                 functionDescriptor, asmMethod, jvmSignature, mv,
                 isCompatibilityStubInDefaultImpls ? Collections.singletonList(Deprecated.class) : Collections.emptyList(),
@@ -533,14 +532,18 @@ public class FunctionCodegen {
                     ? iterator.next()
                     : kind == JvmMethodParameterKind.RECEIVER
                       ? JvmCodegenUtil.getDirectMember(functionDescriptor).getExtensionReceiverParameter()
-                      : isDefaultImpl && kind == JvmMethodParameterKind.THIS ? JvmCodegenUtil.getDirectMember(functionDescriptor)
+                      : kind == JvmMethodParameterKind.THIS && isDefaultImpl
-                              .getDispatchReceiverParameter() : null;
+                        ? JvmCodegenUtil.getDirectMember(functionDescriptor).getDispatchReceiverParameter()
+                        : null;
 
             if (annotated != null) {
-                //noinspection ConstantConditions
                 int parameterIndex = i - syntheticParameterCount;
-                AnnotationCodegen.forParameter(parameterIndex, mv, memberCodegen, state, skipNullabilityAnnotations)
+                AnnotationCodegen
-                        .genAnnotations(annotated, parameterSignature.getAsmType(), annotated.getReturnType(), functionDescriptor, Collections.emptyList());
+                        .forParameter(parameterIndex, mv, memberCodegen, state, skipNullabilityAnnotations)
+                        .genAnnotations(
+                                annotated, parameterSignature.getAsmType(), annotated.getReturnType(), functionDescriptor,
+                                Collections.emptyList()
+                        );
             }
         }
     }

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

@@ -16,7 +16,6 @@ import org.jetbrains.kotlin.codegen.state.KotlinTypeMapper;
 import org.jetbrains.kotlin.descriptors.ClassDescriptor;
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor;
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor;
-import org.jetbrains.kotlin.lexer.KtTokens;
 import org.jetbrains.kotlin.psi.KtClassOrObject;
 import org.jetbrains.kotlin.resolve.BindingContext;
 import org.jetbrains.kotlin.resolve.InlineClassesUtilsKt;
@@ -46,6 +45,7 @@ public class FunctionsFromAnyGeneratorImpl extends FunctionsFromAnyGenerator {
     private final GenerationState generationState;
     private final KotlinTypeMapper typeMapper;
     private final JvmKotlinType underlyingType;
+    private final boolean isInErasedInlineClass;
 
     public FunctionsFromAnyGeneratorImpl(
             @NotNull KtClassOrObject declaration,
@@ -67,23 +67,27 @@ public class FunctionsFromAnyGeneratorImpl extends FunctionsFromAnyGenerator {
                 typeMapper.mapType(descriptor),
                 InlineClassesUtilsKt.substitutedUnderlyingType(descriptor.getDefaultType())
         );
+        this.isInErasedInlineClass = fieldOwnerContext.getContextKind() == OwnerKind.ERASED_INLINE_CLASS;
     }
 
     @Override
     protected void generateToStringMethod(
-            @NotNull FunctionDescriptor function, @NotNull List<? extends PropertyDescriptor> properties
+            @NotNull FunctionDescriptor function,
+            @NotNull List<? extends PropertyDescriptor> properties
     ) {
         MethodContext context = fieldOwnerContext.intoFunction(function);
         JvmDeclarationOrigin methodOrigin = JvmDeclarationOriginKt.OtherOrigin(function);
         String toStringMethodName = mapFunctionName(function);
         MethodVisitor mv = v.newMethod(methodOrigin, getAccess(), toStringMethodName, getToStringDesc(), null, null);
 
-        if (fieldOwnerContext.getContextKind() != OwnerKind.ERASED_INLINE_CLASS && classDescriptor.isInline()) {
+        if (!isInErasedInlineClass && classDescriptor.isInline()) {
             FunctionCodegen.generateMethodInsideInlineClassWrapper(methodOrigin, function, classDescriptor, mv, typeMapper);
             return;
         }
 
-        visitEndForAnnotationVisitor(mv.visitAnnotation(Type.getDescriptor(NotNull.class), false));
+        if (!isInErasedInlineClass) {
+            visitEndForAnnotationVisitor(mv.visitAnnotation(Type.getDescriptor(NotNull.class), false));
+        }
 
         if (!generationState.getClassBuilderMode().generateBodies) {
             FunctionCodegen.endVisit(mv, toStringMethodName, getDeclaration());
@@ -144,7 +148,7 @@ public class FunctionsFromAnyGeneratorImpl extends FunctionsFromAnyGenerator {
         String hashCodeMethodName = mapFunctionName(function);
         MethodVisitor mv = v.newMethod(methodOrigin, getAccess(), hashCodeMethodName, getHashCodeDesc(), null, null);
 
-        if (fieldOwnerContext.getContextKind() != OwnerKind.ERASED_INLINE_CLASS && classDescriptor.isInline()) {
+        if (!isInErasedInlineClass && classDescriptor.isInline()) {
             FunctionCodegen.generateMethodInsideInlineClassWrapper(methodOrigin, function, classDescriptor, mv, typeMapper);
             return;
         }
@@ -213,15 +217,14 @@ public class FunctionsFromAnyGeneratorImpl extends FunctionsFromAnyGenerator {
         String equalsMethodName = mapFunctionName(function);
         MethodVisitor mv = v.newMethod(methodOrigin, getAccess(), equalsMethodName, getEqualsDesc(), null, null);
 
-        boolean isErasedInlineClassKind = fieldOwnerContext.getContextKind() == OwnerKind.ERASED_INLINE_CLASS;
+        if (!isInErasedInlineClass && classDescriptor.isInline()) {
-        if (!isErasedInlineClassKind && classDescriptor.isInline()) {
             FunctionCodegen.generateMethodInsideInlineClassWrapper(methodOrigin, function, classDescriptor, mv, typeMapper);
             return;
         }
 
-        visitEndForAnnotationVisitor(
+        if (!isInErasedInlineClass) {
-                mv.visitParameterAnnotation(isErasedInlineClassKind ? 1 : 0, Type.getDescriptor(Nullable.class), false)
+            visitEndForAnnotationVisitor(mv.visitParameterAnnotation(0, Type.getDescriptor(Nullable.class), false));
-        );
+        }
 
         if (!generationState.getClassBuilderMode().generateBodies) {
             FunctionCodegen.endVisit(mv, equalsMethodName, getDeclaration());