[Wasm] Add EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE K2 diagnostic

Prohibit extending non-external types with external types (same as K1)

Issue KT-56849

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirWasmDiagnosticsList.kt

@@ -20,5 +20,8 @@ object WASM_DIAGNOSTICS_LIST : DiagnosticList("FirWasmErrors") {
         val NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE by error<KtElement>(PositioningStrategy.DECLARATION_SIGNATURE_OR_DEFAULT) {
             parameter<ConeKotlinType>("superType")
         }
+        val EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE by error<KtElement>(PositioningStrategy.DECLARATION_SIGNATURE_OR_DEFAULT) {
+            parameter<ConeKotlinType>("superType")
+        }
     }
 }

compiler/fir/checkers/checkers.wasm/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/wasm/FirWasmErrors.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.psi.KtElement
 object FirWasmErrors {
     // Externals
     val NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE by error1<KtElement, ConeKotlinType>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
+    val EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE by error1<KtElement, ConeKotlinType>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
 
     init {
         RootDiagnosticRendererFactory.registerFactory(FirWasmErrorsDefaultMessages)

compiler/fir/checkers/checkers.wasm/src/org/jetbrains/kotlin/fir/analysis/diagnostics/wasm/FirWasmErrorsDefaultMessages.kt

@@ -8,11 +8,13 @@ package org.jetbrains.kotlin.fir.analysis.diagnostics.wasm
 import org.jetbrains.kotlin.diagnostics.KtDiagnosticFactoryToRendererMap
 import org.jetbrains.kotlin.diagnostics.rendering.BaseDiagnosticRendererFactory
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers
+import org.jetbrains.kotlin.fir.analysis.diagnostics.wasm.FirWasmErrors.EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.wasm.FirWasmErrors.NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE
 
 @Suppress("unused")
 object FirWasmErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
     override val MAP = KtDiagnosticFactoryToRendererMap("FIR").also { map ->
         map.put(NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE, "Non-external type extends external type {0}", FirDiagnosticRenderers.RENDER_TYPE)
+        map.put(EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE, "External type extends non-external type {0}", FirDiagnosticRenderers.RENDER_TYPE)
     }
 }

compiler/fir/checkers/checkers.wasm/src/org/jetbrains/kotlin/fir/analysis/wasm/checkers/declaration/FirWasmExternalInheritanceChecker.kt

@@ -5,29 +5,45 @@
 
 package org.jetbrains.kotlin.fir.analysis.wasm.checkers.declaration
 
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirClassChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.toClassLikeSymbol
 import org.jetbrains.kotlin.fir.analysis.diagnostics.wasm.FirWasmErrors
-import org.jetbrains.kotlin.fir.declarations.utils.isEffectivelyExternal
 import org.jetbrains.kotlin.fir.declarations.FirClass
+import org.jetbrains.kotlin.fir.declarations.utils.isEffectivelyExternal
 import org.jetbrains.kotlin.fir.types.coneType
+import org.jetbrains.kotlin.name.StandardClassIds
 
 object FirWasmExternalInheritanceChecker : FirClassChecker() {
     override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         val session = context.session
-        if (!declaration.symbol.isEffectivelyExternal(session)) {
-            for (superTypeRef in declaration.superTypeRefs) {
-                if (superTypeRef.toClassLikeSymbol(session)?.isEffectivelyExternal(session) == true) {
-                    reporter.reportOn(
-                        declaration.source,
-                        FirWasmErrors.NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE,
-                        superTypeRef.coneType,
-                        context
-                    )
-                }
+        val isCurrentClassExternal = declaration.symbol.isEffectivelyExternal(session)
+        for (superTypeRef in declaration.superTypeRefs) {
+            val superClass = superTypeRef.toClassLikeSymbol(session) ?: continue
+            if (superClass.classId == StandardClassIds.Any) continue  // External classes can extend Any
+
+            val isSuperClassExternal = superClass.isEffectivelyExternal(session)
+            if (!isCurrentClassExternal && isSuperClassExternal) {
+                reporter.reportOn(
+                    declaration.source,
+                    FirWasmErrors.NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE,
+                    superTypeRef.coneType,
+                    context
+                )
+            } else if (isCurrentClassExternal && !isSuperClassExternal) {
+                // External enum and annotation classes are prohibited, but they add implicit non-external super types. Skip reporting errors for them.
+                if (declaration.classKind == ClassKind.ANNOTATION_CLASS && superClass.classId == StandardClassIds.Annotation) continue
+                if (declaration.classKind == ClassKind.ENUM_CLASS && superClass.classId == StandardClassIds.Enum) continue
+
+                reporter.reportOn(
+                    declaration.source,
+                    FirWasmErrors.EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE,
+                    superTypeRef.coneType,
+                    context
+                )
             }
         }
     }

compiler/testData/diagnostics/wasmTests/jsInterop/inheritance.fir.kt

@@ -4,11 +4,11 @@ interface I1
 
 external open class EC1
 
-external class EC2 : C1
+external class <!EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE!>EC2<!> : C1
 
-external class EC3 : I1, C1
+external class <!EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE, EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE!>EC3<!> : I1, C1
 
-external interface EI1 : I1
+external interface <!EXTERNAL_TYPE_EXTENDS_NON_EXTERNAL_TYPE!>EI1<!> : I1
 
 interface <!NON_EXTERNAL_TYPE_EXTENDS_EXTERNAL_TYPE!>I2<!> : EI1