IC: Forbid inner classes inside inline classes

#KT-43067 Fixed

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/fir/FirOldFrontendDiagnosticsTestGenerated.java

@@ -12917,6 +12917,11 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirOldFronte
             runTest("compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.kt");
         }
 
+        @TestMetadata("innerClassInsideInlineClass.kt")
+        public void testInnerClassInsideInlineClass() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.kt");
+        }
+
         @TestMetadata("lateinitInlineClasses.kt")
         public void testLateinitInlineClasses() throws Exception {
             runTest("compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.kt");

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -362,6 +362,7 @@ public interface Errors {
     DiagnosticFactory0<KtTypeReference> INLINE_CLASS_CANNOT_BE_RECURSIVE = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory1<PsiElement, String> RESERVED_MEMBER_INSIDE_INLINE_CLASS = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory0<PsiElement> SECONDARY_CONSTRUCTOR_WITH_BODY_INSIDE_INLINE_CLASS = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<PsiElement> INNER_CLASS_INSIDE_INLINE_CLASS = DiagnosticFactory0.create(ERROR);
 
     // Result class
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -717,6 +717,7 @@ public class DefaultErrorMessages {
         MAP.put(INLINE_CLASS_CANNOT_BE_RECURSIVE, "Inline class cannot be recursive");
         MAP.put(RESERVED_MEMBER_INSIDE_INLINE_CLASS, "Member with the name ''{0}'' is reserved for future releases", STRING);
         MAP.put(SECONDARY_CONSTRUCTOR_WITH_BODY_INSIDE_INLINE_CLASS, "Secondary constructors with bodies are reserved for for future releases");
+        MAP.put(INNER_CLASS_INSIDE_INLINE_CLASS, "Inline class cannot have inner classes");
 
         MAP.put(RESULT_CLASS_IN_RETURN_TYPE, "'kotlin.Result' cannot be used as a return type");
         MAP.put(RESULT_CLASS_WITH_NULLABLE_OPERATOR, "Expression of type 'kotlin.Result' cannot be used as a left operand of ''{0}''", STRING);

compiler/frontend/src/org/jetbrains/kotlin/resolve/PlatformConfiguratorBase.kt

@@ -28,6 +28,7 @@ private val DEFAULT_DECLARATION_CHECKERS = listOf(
     SuspendLimitationsChecker,
     InlineClassDeclarationChecker,
     PropertiesWithBackingFieldsInsideInlineClass(),
+    InnerClassInsideInlineClass(),
     AnnotationClassTargetAndRetentionChecker(),
     ReservedMembersAndConstructsForInlineClass(),
     ResultClassInReturnTypeChecker(),

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/InlineClassDeclarationChecker.kt

@@ -124,6 +124,18 @@ class PropertiesWithBackingFieldsInsideInlineClass : DeclarationChecker {
     }
 }
 
+class InnerClassInsideInlineClass : DeclarationChecker {
+    override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
+        if (declaration !is KtClass) return
+        if (descriptor !is ClassDescriptor) return
+        if (!descriptor.isInner) return
+
+        if (!descriptor.containingDeclaration.isInlineClass()) return
+
+        context.trace.report(Errors.INNER_CLASS_INSIDE_INLINE_CLASS.on(declaration.modifierList!!.getModifier(KtTokens.INNER_KEYWORD)!!))
+    }
+}
+
 class ReservedMembersAndConstructsForInlineClass : DeclarationChecker {
 
     companion object {

compiler/testData/codegen/box/inlineClasses/kt27705.kt

@@ -2,6 +2,7 @@
 // WITH_RUNTIME
 
 inline class Z(val x: Int) {
+    @Suppress("INNER_CLASS_INSIDE_INLINE_CLASS")
     inner class Inner(val y: Int) {
         val xx = x
     }

compiler/testData/codegen/box/inlineClasses/kt27706.kt

@@ -2,6 +2,7 @@
 // WITH_RUNTIME
 
 inline class Z(val x: Int) {
+    @Suppress("INNER_CLASS_INSIDE_INLINE_CLASS")
     inner class Inner(val z: Z) {
         val xx = x
     }

compiler/testData/codegen/box/reflection/call/inlineClasses/constructorWithInlineClassParameters.kt

@@ -12,6 +12,7 @@ class Outer(val z1: Z) {
 }
 
 inline class InlineOuter(val z1: Z) {
+    @Suppress("INNER_CLASS_INSIDE_INLINE_CLASS")
     inner class Inner(val z2: Z) {
         val test = "$z1 $z2"
     }

compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.fir.kt

@@ -0,0 +1,8 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline class Foo(val x: Int) {
+    inner class InnerC
+    inner object InnerO
+    inner interface InnerI
+}

compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.kt

@@ -0,0 +1,8 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline class Foo(val x: Int) {
+    <!INNER_CLASS_INSIDE_INLINE_CLASS!>inner<!> class InnerC
+    <!WRONG_MODIFIER_TARGET!>inner<!> object InnerO
+    <!WRONG_MODIFIER_TARGET!>inner<!> interface InnerI
+}

compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.txt

@@ -0,0 +1,29 @@
+package
+
+public final inline class Foo {
+    public constructor Foo(/*0*/ x: kotlin.Int)
+    public final val x: kotlin.Int
+    public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*synthesized*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+
+    public final inner class InnerC {
+        public constructor InnerC()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    public interface InnerI {
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    public object InnerO {
+        private constructor InnerO()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}

compiler/tests-gen/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -12924,6 +12924,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTestWithFirVali
                 runTest("compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.kt");
             }
 
+            @TestMetadata("innerClassInsideInlineClass.kt")
+            public void testInnerClassInsideInlineClass() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.kt");
+            }
+
             @TestMetadata("lateinitInlineClasses.kt")
             public void testLateinitInlineClasses() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.kt");

compiler/tests-gen/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -12919,6 +12919,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.kt");
             }
 
+            @TestMetadata("innerClassInsideInlineClass.kt")
+            public void testInnerClassInsideInlineClass() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inlineClasses/innerClassInsideInlineClass.kt");
+            }
+
             @TestMetadata("lateinitInlineClasses.kt")
             public void testLateinitInlineClasses() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.kt");