[FIR JS] Support WRONG_MULTIPLE_INHERITANCE

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

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.diagnostics.*
 import org.jetbrains.kotlin.diagnostics.SourceElementPositioningStrategies
 import org.jetbrains.kotlin.diagnostics.rendering.RootDiagnosticRendererFactory
 import org.jetbrains.kotlin.fir.analysis.diagnostics.*
+import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.psi.KtElement
 
 /*
@@ -23,6 +24,9 @@ object FirJsErrors {
     val JS_MODULE_PROHIBITED_ON_NON_NATIVE by error0<KtElement>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
     val NESTED_JS_MODULE_PROHIBITED by error0<KtElement>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
 
+    // Supertypes
+    val WRONG_MULTIPLE_INHERITANCE by error1<KtElement, FirCallableSymbol<*>>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
+
     init {
         RootDiagnosticRendererFactory.registerFactory(FirJsErrorsDefaultMessages)
     }

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

@@ -7,11 +7,13 @@ package org.jetbrains.kotlin.fir.analysis.diagnostics.js
 
 import org.jetbrains.kotlin.diagnostics.KtDiagnosticFactoryToRendererMap
 import org.jetbrains.kotlin.diagnostics.rendering.BaseDiagnosticRendererFactory
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers
 import org.jetbrains.kotlin.fir.analysis.diagnostics.checkMissingMessages
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.JS_MODULE_PROHIBITED_ON_NON_NATIVE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.JS_MODULE_PROHIBITED_ON_VAR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.NESTED_JS_MODULE_PROHIBITED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.WRONG_JS_QUALIFIER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors.WRONG_MULTIPLE_INHERITANCE
 
 @Suppress("unused")
 object FirJsErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
@@ -23,6 +25,11 @@ object FirJsErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
             NESTED_JS_MODULE_PROHIBITED,
             "@JsModule and @JsNonModule can't appear on here since the file is already marked by either @JsModule or @JsNonModule"
         )
+        map.put(
+            WRONG_MULTIPLE_INHERITANCE,
+            "Can''t apply multiple inheritance here, since it''s impossible to generate bridge for system function {0}",
+            FirDiagnosticRenderers.SYMBOL
+        )
 
         map.checkMissingMessages(FirJsErrors)
     }

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

@@ -5,13 +5,8 @@
 
 package org.jetbrains.kotlin.fir.analysis.js.checkers
 
-import org.jetbrains.kotlin.fir.analysis.checkers.declaration.DeclarationCheckers
-import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirBasicDeclarationChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirFunctionChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirPropertyChecker
-import org.jetbrains.kotlin.fir.analysis.js.checkers.declaration.FirJsInlineDeclarationChecker
-import org.jetbrains.kotlin.fir.analysis.js.checkers.declaration.FirJsInlinePropertyChecker
-import org.jetbrains.kotlin.fir.analysis.js.checkers.declaration.FirJsModuleChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.*
+import org.jetbrains.kotlin.fir.analysis.js.checkers.declaration.*
 
 object JsDeclarationCheckers : DeclarationCheckers() {
     override val functionCheckers: Set<FirFunctionChecker>
@@ -28,4 +23,9 @@ object JsDeclarationCheckers : DeclarationCheckers() {
         get() = setOf(
             FirJsModuleChecker,
         )
+
+    override val classCheckers: Set<FirClassChecker>
+        get() = setOf(
+            FirJsMultipleInheritanceChecker,
+        )
 }

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

@@ -0,0 +1,64 @@
+/*
+ * 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.builtins.StandardNames
+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.FirClassChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.overriddenFunctions
+import org.jetbrains.kotlin.fir.analysis.checkers.unsubstitutedScope
+import org.jetbrains.kotlin.fir.analysis.diagnostics.js.FirJsErrors
+import org.jetbrains.kotlin.fir.declarations.FirClass
+import org.jetbrains.kotlin.fir.resolve.defaultType
+import org.jetbrains.kotlin.fir.scopes.getFunctions
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
+import org.jetbrains.kotlin.fir.types.classId
+import org.jetbrains.kotlin.fir.types.isSubtypeOf
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.util.OperatorNameConventions
+
+object FirJsMultipleInheritanceChecker : FirClassChecker() {
+    override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
+        declaration.checkFunctionIfSubtypeOf(
+            functionToCheck = OperatorNameConventions.GET,
+            supertype = context.session.builtinTypes.charSequenceType.type,
+            context, reporter,
+        )
+
+        declaration.checkFunctionIfSubtypeOf(
+            functionToCheck = StandardNames.NEXT_CHAR,
+            supertype = context.session.builtinTypes.charIteratorType.type,
+            context, reporter,
+        )
+    }
+
+    private fun FirClass.checkFunctionIfSubtypeOf(
+        functionToCheck: Name,
+        supertype: ConeKotlinType,
+        context: CheckerContext,
+        reporter: DiagnosticReporter,
+    ) {
+        if (!defaultType().isSubtypeOf(supertype, context.session)) {
+            return
+        }
+
+        val scope = unsubstitutedScope(context)
+        val overridesWithSameName = scope.getFunctions(functionToCheck)
+
+        for (function in overridesWithSameName) {
+            val overridden = function.overriddenFunctions(symbol, context)
+
+            if (
+                overridden.size > 1 &&
+                overridden.any { it.callableId.classId == supertype.classId }
+            ) {
+                reporter.reportOn(source, FirJsErrors.WRONG_MULTIPLE_INHERITANCE, function, context)
+            }
+        }
+    }
+}