[FIR JS] Report NESTED_JS_EXPORT

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

@@ -4981,6 +4981,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJsErrors.NESTED_JS_EXPORT) { firDiagnostic ->
+        NestedJsExportImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirJsErrors.DELEGATION_BY_DYNAMIC) { firDiagnostic ->
         DelegationByDynamicImpl(
             firDiagnostic as KtPsiDiagnostic,

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

@@ -3462,6 +3462,10 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ExternalInterfaceAsClassLiteral::class
     }
 
+    abstract class NestedJsExport : KtFirDiagnostic<KtElement>() {
+        override val diagnosticClass get() = NestedJsExport::class
+    }
+
     abstract class DelegationByDynamic : KtFirDiagnostic<KtElement>() {
         override val diagnosticClass get() = DelegationByDynamic::class
     }

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

@@ -4190,6 +4190,11 @@ internal class ExternalInterfaceAsClassLiteralImpl(
     override val token: KtLifetimeToken,
 ) : KtFirDiagnostic.ExternalInterfaceAsClassLiteral(), KtAbstractFirDiagnostic<KtElement>
 
+internal class NestedJsExportImpl(
+    override val firDiagnostic: KtPsiDiagnostic,
+    override val token: KtLifetimeToken,
+) : KtFirDiagnostic.NestedJsExport(), KtAbstractFirDiagnostic<KtElement>
+
 internal class DelegationByDynamicImpl(
     override val firDiagnostic: KtPsiDiagnostic,
     override val token: KtLifetimeToken,

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

@@ -96,6 +96,10 @@ object JS_DIAGNOSTICS_LIST : DiagnosticList("FirJsErrors") {
         val EXTERNAL_INTERFACE_AS_CLASS_LITERAL by error<KtElement>()
     }
 
+    val EXPORT by object : DiagnosticGroup("Export") {
+        val NESTED_JS_EXPORT by error<KtElement>()
+    }
+
     val DYNAMICS by object : DiagnosticGroup("Dynamics") {
         val DELEGATION_BY_DYNAMIC by error<KtElement>()
     }

compiler/fir/checkers/checkers.js/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/js/FirJsErrors.kt

@@ -79,6 +79,9 @@ object FirJsErrors {
     val UNCHECKED_CAST_TO_EXTERNAL_INTERFACE by warning2<KtElement, ConeKotlinType, ConeKotlinType>()
     val EXTERNAL_INTERFACE_AS_CLASS_LITERAL by error0<KtElement>()
 
+    // Export
+    val NESTED_JS_EXPORT by error0<KtElement>()
+
     // Dynamics
     val DELEGATION_BY_DYNAMIC by error0<KtElement>()
 

compiler/fir/checkers/checkers.js/src/org/jetbrains/kotlin/fir/analysis/diagnostics/js/FirJsErrorsDefaultMessages.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NATIVE_INDEX
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NATIVE_SETTER_WRONG_RETURN_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NESTED_CLASS_IN_EXTERNAL_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NESTED_EXTERNAL_DECLARATION
+import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NESTED_JS_EXPORT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NON_EXTERNAL_DECLARATION_IN_INAPPROPRIATE_FILE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.OVERRIDING_EXTERNAL_FUN_WITH_OPTIONAL_PARAMS
@@ -167,6 +168,7 @@ object FirJsErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
             FirDiagnosticRenderers.RENDER_TYPE,
         )
         map.put(EXTERNAL_INTERFACE_AS_CLASS_LITERAL, "Can't refer to external interface from class literal")
+        map.put(NESTED_JS_EXPORT, "@JsExport is only allowed on files and top-level declarations")
 
         map.checkMissingMessages(FirJsErrors)
     }

compiler/fir/checkers/checkers.js/src/org/jetbrains/kotlin/fir/analysis/js/checkers/JsDeclarationCheckers.kt

@@ -27,6 +27,7 @@ object JsDeclarationCheckers : DeclarationCheckers() {
             FirJsExternalChecker,
             FirJsExternalFileChecker,
             FirJsNameChecker,
+            FirJsExportAnnotationChecker,
         )
 
     override val classCheckers: Set<FirClassChecker>

compiler/fir/checkers/checkers.js/src/org/jetbrains/kotlin/fir/analysis/js/checkers/declaration/FirJsExportAnnotationChecker.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.analysis.js.checkers.declaration
+
+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.FirBasicDeclarationChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.isTopLevel
+import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors
+import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirFile
+import org.jetbrains.kotlin.fir.declarations.getAnnotationByClassId
+import org.jetbrains.kotlin.name.JsStandardClassIds
+
+object FirJsExportAnnotationChecker : FirBasicDeclarationChecker() {
+    override fun check(declaration: FirDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
+        val jsExport = declaration.getAnnotationByClassId(JsStandardClassIds.Annotations.JsExport, context.session) ?: return
+
+        if (declaration !is FirFile && !context.isTopLevel) {
+            reporter.reportOn(jsExport.source, FirJsErrors.NESTED_JS_EXPORT, context)
+        }
+    }
+}

compiler/testData/diagnostics/testsWithJsStdLib/export/jsExportOnNestedDeclarations.fir.kt

@@ -1,22 +0,0 @@
-// !OPT_IN: kotlin.js.ExperimentalJsExport
-
-package foo
-
-class C1 {
-    @JsExport
-    fun f1() {}
-
-    @JsExport
-    val p: Int = 10
-
-    @JsExport
-    object O
-}
-
-fun f2() {
-    @JsExport
-    fun f3() {}
-
-    @JsExport
-    class C2
-}

compiler/testData/diagnostics/testsWithJsStdLib/export/jsExportOnNestedDeclarations.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !OPT_IN: kotlin.js.ExperimentalJsExport
 
 package foo