SLC: force boxed return type when needed

e.g., when overriding a function whose return type is not primitive

^KT-57579 Fixed

analysis/analysis-api-fe10/src/org/jetbrains/kotlin/analysis/api/descriptors/components/KtFe10PsiTypeProvider.kt

@@ -62,6 +62,7 @@ internal class KtFe10PsiTypeProvider(
             KtTypeMappingMode.GENERIC_ARGUMENT -> TypeMappingMode.GENERIC_ARGUMENT
             KtTypeMappingMode.SUPER_TYPE -> TypeMappingMode.SUPER_TYPE
             KtTypeMappingMode.SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS -> TypeMappingMode.SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS
+            KtTypeMappingMode.RETURN_TYPE_BOXED -> TypeMappingMode.RETURN_TYPE_BOXED
             KtTypeMappingMode.RETURN_TYPE ->
                 typeMapper.typeContext.getOptimalModeForReturnType(type.fe10Type, isAnnotationMethod)
             KtTypeMappingMode.VALUE_PARAMETER ->

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/components/KtFirPsiTypeProvider.kt

@@ -76,6 +76,7 @@ internal class KtFirPsiTypeProvider(
             KtTypeMappingMode.GENERIC_ARGUMENT -> TypeMappingMode.GENERIC_ARGUMENT
             KtTypeMappingMode.SUPER_TYPE -> TypeMappingMode.SUPER_TYPE
             KtTypeMappingMode.SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS -> TypeMappingMode.SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS
+            KtTypeMappingMode.RETURN_TYPE_BOXED -> TypeMappingMode.RETURN_TYPE_BOXED
             KtTypeMappingMode.RETURN_TYPE ->
                 rootModuleSession.jvmTypeMapper.typeContext.getOptimalModeForReturnType(type.coneType, isAnnotationMethod)
             KtTypeMappingMode.VALUE_PARAMETER ->

analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/types/KtTypeMappingMode.kt

@@ -33,6 +33,11 @@ public enum class KtTypeMappingMode {
      */
     SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS,
 
+    /**
+     * When method return type should be boxed (e.g., kotlin.Int to Ljava/lang/Integer;)
+     */
+    RETURN_TYPE_BOXED,
+
     /**
      * Optimal mode to convert the return type of declarations if it's part of signature.
      */

analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/methods/SymbolLightAccessorMethod.kt

@@ -238,10 +238,19 @@ internal class SymbolLightAccessorMethod private constructor(
         if (!isGetter) return@lazyPub PsiType.VOID
 
         containingPropertySymbolPointer.withSymbol(ktModule) { propertySymbol ->
-            propertySymbol.returnType.asPsiType(
+            val ktType = propertySymbol.returnType
+
+            val forceBoxedReturnType = ktType.isPrimitive &&
+                    propertySymbol.getAllOverriddenSymbols().any { overriddenSymbol ->
+                        !overriddenSymbol.returnType.isPrimitive
+                    }
+
+            val typeMappingMode = if (forceBoxedReturnType) KtTypeMappingMode.RETURN_TYPE_BOXED else KtTypeMappingMode.RETURN_TYPE
+
+            ktType.asPsiType(
                 this@SymbolLightAccessorMethod,
                 allowErrorTypes = true,
-                KtTypeMappingMode.RETURN_TYPE,
+                typeMappingMode,
                 containingClass.isAnnotationType,
             )
         } ?: nonExistentType()

analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/methods/SymbolLightSimpleMethod.kt

@@ -11,6 +11,8 @@ import kotlinx.collections.immutable.mutate
 import org.jetbrains.kotlin.analysis.api.KtAnalysisSession
 import org.jetbrains.kotlin.analysis.api.annotations.hasAnnotation
 import org.jetbrains.kotlin.analysis.api.symbols.KtFunctionSymbol
+import org.jetbrains.kotlin.analysis.api.symbols.KtNamedClassOrObjectSymbol
+import org.jetbrains.kotlin.analysis.api.types.KtNonErrorClassType
 import org.jetbrains.kotlin.analysis.api.types.KtType
 import org.jetbrains.kotlin.analysis.api.types.KtTypeMappingMode
 import org.jetbrains.kotlin.asJava.builder.LightMemberOrigin
@@ -177,6 +179,25 @@ internal class SymbolLightSimpleMethod(
         if (isTopLevel) false else withFunctionSymbol { it.isOverride }
     }
 
+    // Inspired by KotlinTypeMapper#forceBoxedReturnType
+    private fun forceBoxedReturnType(): Boolean {
+        return withFunctionSymbol { functionSymbol ->
+            val returnType = functionSymbol.returnType
+            // 'invoke' methods for lambdas, function literals, and callable references
+            // implicitly override generic 'invoke' from a corresponding base class.
+            if (functionSymbol.isBuiltinFunctionInvoke && returnType.isInlineClassType)
+                return@withFunctionSymbol true
+
+            returnType.isPrimitive &&
+                    functionSymbol.getAllOverriddenSymbols().any { overriddenSymbol ->
+                        !overriddenSymbol.returnType.isPrimitive
+                    }
+        }
+    }
+
+    private val KtType.isInlineClassType: Boolean
+        get() = ((this as? KtNonErrorClassType)?.classSymbol as? KtNamedClassOrObjectSymbol)?.isInline == true
+
     private val KtType.isVoidType: Boolean get() = isUnit && nullabilityType != NullabilityType.Nullable
 
     private val _returnedType: PsiType by lazyPub {
@@ -187,10 +208,12 @@ internal class SymbolLightSimpleMethod(
                 functionSymbol.returnType.takeUnless { it.isVoidType } ?: return@withFunctionSymbol PsiType.VOID
             }
 
+            val typeMappingMode = if (forceBoxedReturnType()) KtTypeMappingMode.RETURN_TYPE_BOXED else KtTypeMappingMode.RETURN_TYPE
+
             ktType.asPsiTypeElement(
                 this@SymbolLightSimpleMethod,
                 allowErrorTypes = true,
-                KtTypeMappingMode.RETURN_TYPE,
+                typeMappingMode,
                 this@SymbolLightSimpleMethod.containingClass.isAnnotationType,
             )?.let {
                 annotateByKtType(it.type, ktType, it, modifierList)

compiler/testData/asJava/lightClasses/lightClassByFqName/nullabilityAnnotations/IntOverridesAny.fir.java

@@ -2,10 +2,10 @@ public final class C /* C*/ implements Tr {
   private final int v;
 
   @java.lang.Override()
-  public int foo();//  foo()
+  public java.lang.Integer foo();//  foo()
 
   @java.lang.Override()
-  public int getV();//  getV()
+  public java.lang.Integer getV();//  getV()
 
   public  C();//  .ctor()
 }