Generalize FirInterfaceWithSuperclassChecker to FirSupertypesChecker

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

@@ -1,26 +0,0 @@
-/*
- * Copyright 2010-2020 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.checkers.declaration
-
-import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
-import org.jetbrains.kotlin.fir.analysis.checkers.findNonInterfaceSupertype
-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.FirRegularClass
-import org.jetbrains.kotlin.fir.declarations.isInterface
-
-object FirInterfaceWithSuperclassChecker : FirRegularClassChecker() {
-    override fun check(declaration: FirRegularClass, context: CheckerContext, reporter: DiagnosticReporter) {
-        if (!declaration.isInterface) {
-            return
-        }
-
-        declaration.findNonInterfaceSupertype(context)?.let {
-            reporter.reportOn(it.source, FirErrors.INTERFACE_WITH_SUPERCLASS, context)
-        }
-    }
-}

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

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2010-2020 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.checkers.declaration
+
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+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.FirClass
+import org.jetbrains.kotlin.fir.resolve.toSymbol
+import org.jetbrains.kotlin.fir.types.ConeClassLikeType
+import org.jetbrains.kotlin.fir.types.coneType
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+
+object FirSupertypesChecker : FirClassChecker() {
+    override fun check(declaration: FirClass<*>, context: CheckerContext, reporter: DiagnosticReporter) {
+        val isInterface = declaration.classKind == ClassKind.INTERFACE
+        for (superTypeRef in declaration.superTypeRefs) {
+            val lookupTag = superTypeRef.coneType.safeAs<ConeClassLikeType>()?.lookupTag ?: continue
+            val superTypeFir = lookupTag.toSymbol(context.session)?.fir
+
+            if (isInterface && superTypeFir is FirClass<*> && superTypeFir.classKind != ClassKind.INTERFACE) {
+                reporter.reportOn(superTypeRef.source, FirErrors.INTERFACE_WITH_SUPERCLASS, context)
+                return
+            }
+        }
+    }
+}

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

@@ -75,7 +75,7 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirDelegationSuperCallInEnumConstructorChecker,
             FirDelegationInInterfaceSyntaxChecker,
             FirEnumClassSimpleChecker,
-            FirInterfaceWithSuperclassChecker,
+            FirSupertypesChecker,
             FirLocalEntityNotAllowedChecker,
             FirManyCompanionObjectsChecker,
             FirMethodOfAnyImplementedInInterfaceChecker,