FIR: check multiple vararg param and forbidden vararg type

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

@@ -840,6 +840,19 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.MULTIPLE_VARARG_PARAMETERS) { firDiagnostic ->
+        MultipleVarargParametersImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
+    add(FirErrors.FORBIDDEN_VARARG_PARAMETER_TYPE) { firDiagnostic ->
+        ForbiddenVarargParameterTypeImpl(
+            firSymbolBuilder.buildKtType(firDiagnostic.a),
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.ABSTRACT_PROPERTY_IN_NON_ABSTRACT_CLASS) { firDiagnostic ->
         AbstractPropertyInNonAbstractClassImpl(
             firSymbolBuilder.buildSymbol(firDiagnostic.a as FirDeclaration),

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

@@ -594,6 +594,15 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = UselessVarargOnParameter::class
     }
 
+    abstract class MultipleVarargParameters : KtFirDiagnostic<KtParameter>() {
+        override val diagnosticClass get() = MultipleVarargParameters::class
+    }
+
+    abstract class ForbiddenVarargParameterType : KtFirDiagnostic<KtParameter>() {
+        override val diagnosticClass get() = ForbiddenVarargParameterType::class
+        abstract val varargParameterType: KtType
+    }
+
     abstract class AbstractPropertyInNonAbstractClass : KtFirDiagnostic<KtModifierListOwner>() {
         override val diagnosticClass get() = AbstractPropertyInNonAbstractClass::class
         abstract val property: KtSymbol

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

@@ -952,6 +952,21 @@ internal class UselessVarargOnParameterImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class MultipleVarargParametersImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.MultipleVarargParameters(), KtAbstractFirDiagnostic<KtParameter> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
+internal class ForbiddenVarargParameterTypeImpl(
+    override val varargParameterType: KtType,
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.ForbiddenVarargParameterType(), KtAbstractFirDiagnostic<KtParameter> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class AbstractPropertyInNonAbstractClassImpl(
     override val property: KtSymbol,
     override val containingClass: KtSymbol,