FIR checker: Make FirJvmExternalDeclarationChecker a

FirMemberDeclarationChecker.

Set isExternal in status for FirRegularClass. Invoke member declaration
checkers for FirRegularClass.

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/jvm/FirJvmExternalDeclarationChecker.kt

@@ -7,24 +7,20 @@ package org.jetbrains.kotlin.fir.analysis.checkers.declaration.jvm
 
 import org.jetbrains.kotlin.fir.FirFakeSourceElementKind
 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.declaration.FirMemberDeclarationChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirModifierList
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
-import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.declarations.*
-import org.jetbrains.kotlin.fir.declarations.FirFunction
-import org.jetbrains.kotlin.fir.declarations.FirProperty
-import org.jetbrains.kotlin.fir.declarations.FirRegularClass
 import org.jetbrains.kotlin.lexer.KtTokens
 
 // TODO: Move this to different, JVM-specific module?
-object FirJvmExternalDeclarationChecker : FirBasicDeclarationChecker() {
+object FirJvmExternalDeclarationChecker : FirMemberDeclarationChecker() {
-    override fun check(declaration: FirDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
+    override fun check(declaration: FirMemberDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
+        if (!declaration.isExternal) return
         val source = declaration.source ?: return
         if (source.kind is FirFakeSourceElementKind) return
-        val modifierList = with(FirModifierList) { source.getModifierList() }
-        val externalModifier = modifierList?.modifiers?.firstOrNull { it.token == KtTokens.EXTERNAL_KEYWORD } ?: return
 
         // WRONG_MODIFIER_TARGET on external constructor is intentionally NOT covered in this checker.
         if (declaration !is FirFunction<*>) {
@@ -33,7 +29,11 @@ object FirJvmExternalDeclarationChecker : FirBasicDeclarationChecker() {
                 is FirRegularClass -> "class"
                 else -> "non-function declaration"
             }
-            reporter.reportOn(externalModifier.source, FirErrors.WRONG_MODIFIER_TARGET, externalModifier.token, target, context)
+            val modifierList = with(FirModifierList) { source.getModifierList() }
+            val externalModifier = modifierList?.modifiers?.firstOrNull { it.token == KtTokens.EXTERNAL_KEYWORD }
+            externalModifier?.let {
+                reporter.reportOn(it.source, FirErrors.WRONG_MODIFIER_TARGET, it.token, target, context)
+            }
         }
 
         // TODO: Implement checkers for these JVM-specific errors (see ExternalFunChecker in FE1.0):

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/components/DeclarationCheckersDiagnosticComponent.kt

@@ -31,7 +31,7 @@ class DeclarationCheckersDiagnosticComponent(
     }
 
     override fun visitRegularClass(regularClass: FirRegularClass, data: CheckerContext) {
-        checkers.regularClassCheckers.check(regularClass, data, reporter)
+        (checkers.memberDeclarationCheckers + checkers.regularClassCheckers).check(regularClass, data, reporter)
     }
 
     override fun visitSimpleFunction(simpleFunction: FirSimpleFunction, data: CheckerContext) {

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/checkers/JvmDeclarationCheckers.kt

@@ -10,7 +10,7 @@ import org.jetbrains.kotlin.fir.analysis.checkers.declaration.jvm.FirJvmExternal
 
 // TODO: Move this to different, JVM-specific module?
 object JvmDeclarationCheckers : DeclarationCheckers() {
-    override val basicDeclarationCheckers: Set<FirBasicDeclarationChecker> = setOf(
+    override val memberDeclarationCheckers: Set<FirMemberDeclarationChecker> = setOf(
         FirJvmExternalDeclarationChecker,
     )
 }

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/DeclarationsConverter.kt

@@ -408,6 +408,7 @@ class DeclarationsConverter(
                     isData = modifiers.isDataClass()
                     isInline = modifiers.isInlineClass()
                     isFun = modifiers.isFunctionalInterface()
+                    isExternal = modifiers.hasExternal()
                 }
 
                 buildRegularClass {

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -817,6 +817,7 @@ class RawFirBuilder(
                     isData = classOrObject.hasModifier(DATA_KEYWORD)
                     isInline = classOrObject.hasModifier(INLINE_KEYWORD)
                     isFun = classOrObject.hasModifier(FUN_KEYWORD)
+                    isExternal = classOrObject.hasModifier(EXTERNAL_KEYWORD)
                 }
                 withCapturedTypeParameters {
                     if (!status.isInner) context.capturedTypeParameters = context.capturedTypeParameters.clear()

compiler/testData/diagnostics/tests/modifiers/modifierOnParameterInFunctionType.fir.kt

@@ -26,7 +26,7 @@ val allProhibited: (<!INCOMPATIBLE_MODIFIERS, REDUNDANT_MODIFIER!>abstract<!>
                     <!INCOMPATIBLE_MODIFIERS!>crossinline<!>
                     <!INCOMPATIBLE_MODIFIERS!>data<!>
                     enum
-                    <!WRONG_MODIFIER_TARGET!>external<!>
+                    external
                     <!INCOMPATIBLE_MODIFIERS!>final<!>
                     <!INCOMPATIBLE_MODIFIERS!>in<!>
                     <!INCOMPATIBLE_MODIFIERS!>inline<!>