[FIR] Add JVM diagnostics about external declaration

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -3756,4 +3756,28 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJvmErrors.EXTERNAL_DECLARATION_CANNOT_BE_ABSTRACT) { firDiagnostic ->
+        ExternalDeclarationCannotBeAbstractImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirJvmErrors.EXTERNAL_DECLARATION_CANNOT_HAVE_BODY) { firDiagnostic ->
+        ExternalDeclarationCannotHaveBodyImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirJvmErrors.EXTERNAL_DECLARATION_IN_INTERFACE) { firDiagnostic ->
+        ExternalDeclarationInInterfaceImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirJvmErrors.EXTERNAL_DECLARATION_CANNOT_BE_INLINED) { firDiagnostic ->
+        ExternalDeclarationCannotBeInlinedImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
 }

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -2612,4 +2612,20 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = NonJvmDefaultOverridesJavaDefault::class
     }
 
+    abstract class ExternalDeclarationCannotBeAbstract : KtFirDiagnostic<KtDeclaration>() {
+        override val diagnosticClass get() = ExternalDeclarationCannotBeAbstract::class
+    }
+
+    abstract class ExternalDeclarationCannotHaveBody : KtFirDiagnostic<KtDeclaration>() {
+        override val diagnosticClass get() = ExternalDeclarationCannotHaveBody::class
+    }
+
+    abstract class ExternalDeclarationInInterface : KtFirDiagnostic<KtDeclaration>() {
+        override val diagnosticClass get() = ExternalDeclarationInInterface::class
+    }
+
+    abstract class ExternalDeclarationCannotBeInlined : KtFirDiagnostic<KtDeclaration>() {
+        override val diagnosticClass get() = ExternalDeclarationCannotBeInlined::class
+    }
+
 }

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -4245,3 +4245,31 @@ internal class NonJvmDefaultOverridesJavaDefaultImpl(
     override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
 }
 
+internal class ExternalDeclarationCannotBeAbstractImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ExternalDeclarationCannotBeAbstract(), KtAbstractFirDiagnostic<KtDeclaration> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
+internal class ExternalDeclarationCannotHaveBodyImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ExternalDeclarationCannotHaveBody(), KtAbstractFirDiagnostic<KtDeclaration> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
+internal class ExternalDeclarationInInterfaceImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ExternalDeclarationInInterface(), KtAbstractFirDiagnostic<KtDeclaration> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
+internal class ExternalDeclarationCannotBeInlinedImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ExternalDeclarationCannotBeInlined(), KtAbstractFirDiagnostic<KtDeclaration> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+