[K/JS] Support companion objects in external and exported declarations

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

@@ -5742,6 +5742,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJsErrors.NAMED_COMPANION_IN_EXPORTED_INTERFACE) { firDiagnostic ->
+        NamedCompanionInExportedInterfaceImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirWebCommonErrors.NESTED_JS_EXPORT) { firDiagnostic ->
         NestedJsExportImpl(
             firDiagnostic as KtPsiDiagnostic,
@@ -5881,6 +5887,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirWebCommonErrors.NAMED_COMPANION_IN_EXTERNAL_INTERFACE) { firDiagnostic ->
+        NamedCompanionInExternalInterfaceImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirWebCommonErrors.JSCODE_ARGUMENT_NON_CONST_EXPRESSION) { firDiagnostic ->
         JscodeArgumentNonConstExpressionImpl(
             firDiagnostic as KtPsiDiagnostic,

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

@@ -3999,6 +3999,10 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         val name: String
     }
 
+    interface NamedCompanionInExportedInterface : KtFirDiagnostic<KtElement> {
+        override val diagnosticClass get() = NamedCompanionInExportedInterface::class
+    }
+
     interface NestedJsExport : KtFirDiagnostic<KtElement> {
         override val diagnosticClass get() = NestedJsExport::class
     }
@@ -4094,6 +4098,10 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         val typeArgument: KtType
     }
 
+    interface NamedCompanionInExternalInterface : KtFirDiagnostic<KtElement> {
+        override val diagnosticClass get() = NamedCompanionInExternalInterface::class
+    }
+
     interface JscodeArgumentNonConstExpression : KtFirDiagnostic<KtElement> {
         override val diagnosticClass get() = JscodeArgumentNonConstExpression::class
     }

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

@@ -4828,6 +4828,11 @@ internal class NonConsumableExportedIdentifierImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<KtElement>(firDiagnostic, token), KtFirDiagnostic.NonConsumableExportedIdentifier
 
+internal class NamedCompanionInExportedInterfaceImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtElement>(firDiagnostic, token), KtFirDiagnostic.NamedCompanionInExportedInterface
+
 internal class NestedJsExportImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,
@@ -4945,6 +4950,11 @@ internal class ExternalInterfaceAsReifiedTypeArgumentImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<KtElement>(firDiagnostic, token), KtFirDiagnostic.ExternalInterfaceAsReifiedTypeArgument
 
+internal class NamedCompanionInExternalInterfaceImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtElement>(firDiagnostic, token), KtFirDiagnostic.NamedCompanionInExternalInterface
+
 internal class JscodeArgumentNonConstExpressionImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,