Java

Ansible

AWS CloudFormation Linter

Don't put any logic in createStateDRT-W1023 Don't assign a variable to itselfDRT-W1024 Don't use wildcard parameters or variablesDRT-W1025 Don't use the Null type, unless you are positive that you don't want voidDRT-W1027 Separate the control structure expression from its statementDRT-W1041 Avoid unnecessary containersDRT-W1072 Avoid empty else statementsDRT-W1003 Avoid final for parameter declarationsDRT-W1054 Sort combinator names alphabeticallyDRT-W1080 Avoid `print` calls in production codeDRT-W1004 Don't use more than one case with same valueDRT-W1022 Sort pub dependencies alphabeticallyDRT-W1039 Avoid bool literals in conditional expressionsDRT-W1046 Avoid shadowing type parametersDRT-W1069 Name extensions using UpperCamelCaseDRT-W1076 Prefer using lowerCamelCase for constant namesDRT-W1082 Attach library doc comments to library directivesDRT-W1084 Deprecated member used in the same packageDRT-W1015 Prefer relative imports for files in `lib/`DRT-W1026 Avoid relative imports for files in `lib/`DRT-W1001 Avoid slow async `dart:io` methodsDRT-W1006 Avoid <Type>.toString() in production code since results may be minifiedDRT-W1007 Avoid types as parameter namesDRT-W1008 Avoid using web-only libraries outside Flutter web plugin packagesDRT-W1009 Cancel instances of dart.async.StreamSubscriptionDRT-W1010 Close instances of `dart.core.Sink`DRT-W1011 Put required named parameters firstDRT-W1042 Only reference in scope identifiers in doc commentsDRT-W1013 Avoid control flow in finally blocksDRT-W1014 DO reference all public properties in debug methodsDRT-W1016 Don't invoke asynchronous functions in non-async blocksDRT-W1017 Avoid empty statementsDRT-W1018 Boolean expression composed only with literalsDRT-W1020 Don't use adjacent strings in listDRT-W1021 Test type arguments in operator ==(Object other)DRT-W1028 Avoid `throw` in finally blockDRT-W1029 Avoid using unnecessary statementsDRT-W1030 Equality operator `==` invocation with references of unrelated typesDRT-W1031 Avoid unsafe HTML APIsDRT-W1032 Do not use BuildContexts across async gapsDRT-W1033 Use key in widget constructorsDRT-W1034 Use valid regular expression syntaxDRT-W1035 Depend on referenced packagesDRT-W1036 Use secure urls in `pubspec.yaml`DRT-W1038 Declare method return typesDRT-W1040 Avoid relative imports for files in `lib/`DRT-W1005 Invocation of various collection methods with arguments of unrelated typesDRT-W1012 Specify type annotationsDRT-W1043 Annotate overridden membersDRT-W1044 Avoid annotating with dynamic when not requiredDRT-W1045 Avoid field initializers in const classesDRT-W1053 Avoid catches without on clausesDRT-W1047 Don't explicitly catch Error or types that implement itDRT-W1048 Avoid defining a class that contains only static membersDRT-W1049 Avoid double and int checksDRT-W1050 Avoid overloading operator == and hashCode on classes not marked `@immutable`DRT-W1051 Avoid escaping inner quotes by converting surrounding quotesDRT-W1052 Avoid using `forEach` with a function literalDRT-W1055 Don't implement classes that override `==`DRT-W1056 Don't explicitly initialize variables to nullDRT-W1057 Avoid JavaScript rounded intsDRT-W1058 Don't declare multiple variables on a single lineDRT-W1059 Don't check for null in custom == operatorsDRT-W1060 Avoid positional boolean parametersDRT-W1061 Avoid private typedef functionsDRT-W1062 Avoid redundant argument valuesDRT-W1063 Don't rename parameters of overridden methodsDRT-W1064 Avoid return types on settersDRT-W1065 Avoid setters without gettersDRT-W1068 Avoid single cascade in expression statementsDRT-W1070 Avoid defining unused parameters in constructorsDRT-W1073 Avoid async functions that return voidDRT-W1074 Await only futuresDRT-W1075 Name types using UpperCamelCaseDRT-W1077 Cascade consecutive method invocations on the same referenceDRT-W1078 Don't cast a nullable value to a non nullable typeDRT-W1079 Missing conditional importDRT-W1081 DO use curly braces for all flow control structuresDRT-W1083 Missing deprecated annotationDRT-W1085 Always override `hashCode` if overriding `==`DRT-W1019 Adhere to Effective Dart Guide directives sorting conventionsDRT-W1086 Do not use environment declared variablesDRT-W1087 Use `lowercase_with_underscores` for package namesDRT-W1037 Avoid returning this from methods just to enable a fluent interfaceDRT-W1067 Avoid annotating types for function expression parametersDRT-W1071 Avoid method calls or property accesses on a "dynamic" targetDRT-W1002 Avoid returning null for voidDRT-W1066 Use interpolation to compose strings and valuesDRT-W1146 Unnecessary new keywordDRT-W1182 Missing whitespace between adjacent stringsDRT-W1104 Provide doc comments for all public APIsDRT-W1117 Parameter type mismatch for constant constructorDRT-W1265 Remove deprecated key from `pubspec.yaml`DRT-W1297 The operator x ~/ y is more efficient than (x / y).toInt()DRT-W1302 Only throw instances of classes extending either Exception or ErrorDRT-W1115 Prefer putting asserts in initializer listsDRT-W1121 Integer literal exceeds 64-bit representation limitDRT-W1406 Prefer final in for-each loop variable if reference is not reassignedDRT-W1134 Use a function declaration to bind a function to a nameDRT-W1139 Prefer using null aware operatorsDRT-W1153 Don't create a lambda when a tear-off will doDRT-W1179 Remove unnecessary backslashes in stringsDRT-W1190 Unnecessary string interpolationDRT-W1191 Unnecessary toList() in spreadsDRT-W1193 Prefer intValue.isOdd/isEven instead of checking the result of % 2DRT-W1201 Concrete classes can't have 'Enum' as a superinterfaceDRT-W1257 Duplicate part directivesDRT-W1312 Use `lowercase_with_underscores` when specifying a library prefixDRT-W1100 Don't use null check on a potentially nullable type parameterDRT-W1111 The 'name' field is required but missingDRT-W1476 Prefer using `??=` over testing for nullDRT-W1124 Prefer const literals as parameters of constructors on @immutable classesDRT-W1128 Prefer to use whereType on iterableDRT-W1150 Prefer using mixinsDRT-W1151 Sort constructor declarations before other membersDRT-W1165 Avoid using `null` in `if null` operatorsDRT-W1185 Use if-null operators to convert nulls to boolsDRT-W1200 Use a setter for operations that conceptually change a propertyDRT-W1205 Invalid assignment of a value marked with `doNotStore`DRT-W1232 Invalid usage of non-mixin class as a mixinDRT-W1254 An extension override can't be used to access a static member from an extensionDRT-W1349 The value of the 'flutter' field is expected to be a mapDRT-W1372 Inline function types can't be used for parameters in a generic function typeDRT-W1423 Non-type name used as typeDRT-W1538 Missing positional arguments in function invocationDRT-W1540 Annotation creation must have argumentsDRT-W1545 Missing dart libraryDRT-W1470 Named parameters can't start with an underscoreDRT-W1578 The expression in an assert must be of type 'bool'DRT-W1506 Enums can only declare final fieldsDRT-W1526 Deferred classes can't be used as superclass constraintsDRT-W1493 Avoid empty catch blocksDRT-W1088 Prefer const over final for declarationsDRT-W1127 Use `;` instead of `{}` for empty constructor bodiesDRT-W1089 Put a single newline at end of fileDRT-W1090 Define case clauses for all constants in enum-like classesDRT-W1091 Name source files using `lowercase_with_underscores`DRT-W1092 Use Flutter TODO format: // TODO(username): message, https://URL-to-issueDRT-W1093 Don't import implementation files from another packageDRT-W1094 Explicitly tear-off `call` methods when using an object as a FunctionDRT-W1095 Join return statement with assignment when possibleDRT-W1096 Start multiline strings with a newlineDRT-W1097 Attach library annotations to library directivesDRT-W1098 Name libraries using `lowercase_with_underscores`DRT-W1099 Avoid using private types in public APIsDRT-W1101 Avoid lines longer than 80 charactersDRT-W1102 Use matching super parameter namesDRT-W1103 Avoid leading underscores for library prefixesDRT-W1105 Avoid leading underscores for local identifiersDRT-W1106 Don't compare booleans to boolean literalsDRT-W1107 Avoid calling toString() on runtimeTypeDRT-W1108 Name non-constant identifiers using lowerCamelCaseDRT-W1109 Noop primitive operationsDRT-W1110 Do not pass `null` as an argument where a closure is expectedDRT-W1112 Omit type annotations for local variablesDRT-W1113 Avoid defining a one-member abstract class when a simple function will doDRT-W1114 Don't override fieldsDRT-W1116 Prefix library names with the package name and a dot-separated pathDRT-W1118 Don't reassign references to parameters of functions or methodsDRT-W1119 Prefer asserts with messageDRT-W1122 Use collection literals when possibleDRT-W1123 Prefer const with constant constructorsDRT-W1125 Prefer defining constructors instead of static methods to create instancesDRT-W1129 Use contains for `List` and `String` instancesDRT-W1130 Prefer double quotes where they won't require escape sequencesDRT-W1131 Use => for short members whose body is a single return statementDRT-W1132 Private field could be finalDRT-W1133 Prefer final for variable declarations if they are not reassignedDRT-W1135 Prefer final for parameter declarations if they are not reassignedDRT-W1136 Prefer 'for' elements when building maps from iterablesDRT-W1137 Don't access members with `this` unless avoiding shadowingDRT-W1192 Use `forEach` to only apply a function to all the elementsDRT-W1138 Prefer generic function type aliasesDRT-W1140 Prefer if elements to conditional expressions where possibleDRT-W1141 Prefer using if null operatorsDRT-W1142 Use initializing formals when possibleDRT-W1143 Inline list item declarations where possibleDRT-W1144 Prefer int literals over double literalsDRT-W1145 Use `isEmpty` for Iterables and MapsDRT-W1147 Prefer is! operatorDRT-W1149 Prefer null aware method callsDRT-W1152 Only use double quotes for strings containing single quotesDRT-W1154 Unreachable top-level members in executable librariesDRT-W1194 Use spread collections when possibleDRT-W1155 Prefer typing uninitialized variables and fieldsDRT-W1156 Provide a deprecation message, via @Deprecated("message")DRT-W1157 Document all public membersDRT-W1158 Property getter recursively returns itselfDRT-W1159 Use trailing commas for all function calls and declarationsDRT-W1160 SizedBox for whitespaceDRT-W1161 Use SizedBox shrink and expand named constructorsDRT-W1162 Prefer using /// for doc commentsDRT-W1163 Use `ColoredBox`DRT-W1195 Sort child properties last in widget instance creationsDRT-W1164 Sort unnamed constructor declarations firstDRT-W1166 Tighten type of initializing formalDRT-W1167 Type annotate public APIsDRT-W1168 Don't type annotate initializing formalsDRT-W1169 Don't use constant patterns with type literalsDRT-W1170 `Future` results in `async` function bodies must be `await`ed or marked `unawaited` using `dart:async`DRT-W1171 Unnecessary await keyword in returnDRT-W1172 Avoid using braces in interpolation when not neededDRT-W1173 Don't use explicit `break`s when a break is impliedDRT-W1174 Unnecessary `.new` constructor nameDRT-W1176 The keyword 'final' isn't necessary because the parameter is implicitly 'final'DRT-W1177 Avoid wrapping fields in getters and setters just to be "safe"DRT-W1178 Don't specify the `late` modifier when it is not neededDRT-W1180 Unnecessary null aware operator on extension on a nullable typeDRT-W1184 Use a non-nullable type for a final variable initialized with a non-nullable valueDRT-W1186 Don't override a method to do a super method invocation with the same parametersDRT-W1187 Unnecessary parentheses can be removedDRT-W1188 Unnecessary raw stringDRT-W1189 Use `DecoratedBox`DRT-W1196 Use enums rather than classes that behave like enumsDRT-W1197 Prefer an 8-digit hexadecimal integer(0xFFFFFFFF) to instantiate ColorDRT-W1198 Use predefined named constantsDRT-W1202 Use raw string to avoid escapesDRT-W1203 Use rethrow to rethrow a caught exceptionDRT-W1204 Use string buffers to compose stringsDRT-W1206 Use throwsA matcher instead of fail()DRT-W1208 Start the name of the method with to/_to or as/_as if applicableDRT-W1209 Don't assign to voidDRT-W1210 Classes extending 'AbiSpecificInteger' must have exactly one const constructor, no other members, and no type parametersDRT-W1211 Types can't be assigned a valueDRT-W1239 Classes extending 'AbiSpecificInteger' must have exactly one 'AbiSpecificIntegerMapping' annotation specifying the mapping from ABI to a 'NativeType' integer with a fixed sizeDRT-W1212 Classes extending 'AbiSpecificInteger' must have exactly one 'AbiSpecificIntegerMapping' annotation specifying the mapping from ABI to a 'NativeType' integer with a fixed sizeDRT-W1213 Invalid mapping type in `AbiSpecificIntegerMapping` annotationDRT-W1214 Abstract fields can't have initializersDRT-W1215 A 'sealed' class can't be marked 'abstract' because it's already implicitly abstractDRT-W1216 Multiple libraries export the same nameDRT-W1218 Ambiguous member referenceDRT-W1219 Functions can't be assigned a valueDRT-W1237 Ambiguous importDRT-W1220 The literal can't be either a map or a set because it contains at least one literal map entry or a spread operator spreading a 'Map', and at least one element which is neither of theseDRT-W1221 This literal must be either a map or a set, but the elements don't have enough information for type inference to workDRT-W1222 Fields in a struct class whose type is 'Pointer' shouldn't have any annotationsDRT-W1223 Argument must be a constantDRT-W1224 Unassignable argument typeDRT-W1225 Methods can't be assigned a valueDRT-W1238 Incompatible function signature for `Future.catchError` argumentDRT-W1226 A redirecting constructor can't have an 'assert' initializerDRT-W1227 Asset directory does not existDRT-W1228 Asset does not existDRT-W1229 The value of the 'asset' field is expected to be a list of relative file pathsDRT-W1230 Assets are required to be file paths (strings)DRT-W1231 Constant variables can't be assigned a valueDRT-W1233 Invalid setter invocation for final fieldDRT-W1234 Final variable cannot be reassignedDRT-W1235 Missing setter for getterDRT-W1236 The async for-in loop can only be used in an async functionDRT-W1240 The 'await' expression can't be used in a 'late' local variable's initializerDRT-W1241 Potential implicit return of `null` in method with non-nullable return typeDRT-W1242 Invalid return type for `onError` handlerDRT-W1243 Missing return statement for nullable return typeDRT-W1244 A break label resolves to the 'case' or 'default' statementDRT-W1245 Invalid use of built-in identifier for declaration nameDRT-W1247 The last statement of the 'case' should be 'break', 'continue', 'rethrow', 'return', or 'throw'DRT-W1248 Switch case expression type can't override the '==' operatorDRT-W1249 The switch case expression type must be a subtype of the switch expression typeDRT-W1250 Avoid const keywordDRT-W1175 Use string in part of directivesDRT-W1207 Nullable variable cast to non-nullable type without being assignedDRT-W1251 This cast always throws an exception because the expression always evaluates to 'null'DRT-W1252 Invalid type in 'as' expressionDRT-W1253 Constant values from a deferred library can't be used as keys in a 'const' map literal. Constant values from a deferred library can't be used as values in a 'const' constructor. Constant values from a deferred library can't be used as values in a 'const' list literal. Constant values from a deferred library can't be used as values in a 'const' map literal. Constant values from a deferred library can't be used as values in a 'const' set literalDRT-W1255 Cannot implement `Finalizable` for a subclass of `Struct` or `Union`DRT-W1256 Missing method body in non-abstract classDRT-W1258 Conflicting names for named constructor and static memberDRT-W1259 Invalid use of built-in identifier as a typeDRT-W1246 Conflicting generic interfacesDRT-W1260 Type parameter has the same name as the class, mixin, or extension that declares itDRT-W1261 Conflicting type variable and memberDRT-W1262 Mismatch between constant pattern and value typeDRT-W1263 The expression of a constant pattern must be a valid constantDRT-W1264 Non-const field initialized in a const constructorDRT-W1266 Constant constructor can't call a non-constant super constructorDRT-W1267 Can't define a const constructor for a class with non-final fieldsDRT-W1268 Deferred classes can't be created with 'const'DRT-W1269 Const variables must be initialized with a constant valueDRT-W1270 Constant values from a deferred library can't be used to initialize a 'const' variableDRT-W1271 Only static fields can be declared as constDRT-W1272 Key in a constant map can't override the `==` operator, or `hashCode`DRT-W1273 Constant must be initializedDRT-W1274 Invalid implementation of `==` or `hashCode` in a constant set elementDRT-W1275 A list or a set is expected in this spreadDRT-W1276 A map is expected in this spreadDRT-W1277 The constructor being called isn't a const constructorDRT-W1278 Arguments of a constant creation must be constant expressionsDRT-W1279 A constant constructor tearoff can't use a type parameter as a type argument. A constant creation can't use a type parameter as a type argument. A constant function tearoff can't use a type parameter as a type argumentDRT-W1280 <a id="continue_label_on_switch" aria-hidden="true"></a>_(Previously known as `continue_label_on_switch`) The label used in a 'continue' statement must be defined on either a loop or a switch memberDRT-W1281 Subclasses of 'Struct' and 'Union' are backed by native memory, and can't be instantiated by a generative constructorDRT-W1282 Invalid class name specified for instance creationDRT-W1283 Dead codeDRT-W1284 Dead code: Catch clauses after a 'catch (e)' or an 'on Object catch (e)' are never reachedDRT-W1285 Unreachable `catch` clause after a more general oneDRT-W1286 The left operand can't be null, so the right operand is never executedDRT-W1287 The default 'List' constructor isn't available when null safety is enabledDRT-W1288 Parameters in a function type can't have default valuesDRT-W1289 Default values aren't allowed in factory constructors that redirect to another constructorDRT-W1290 Required named parameters can't have a default valueDRT-W1291 Imports of deferred libraries must hide all extensionsDRT-W1292 Unassigned late local variable is definitely unassigned at this pointDRT-W1293 Using a colon as the separator before a default value is deprecated and will not be supported in language version 3.0 and laterDRT-W1295 Avoid importing deprecated names from librariesDRT-W1296 Deprecated member used in a different packageDRT-W1298 Using the 'new' keyword in a comment reference is deprecatedDRT-W1299 Extending 'Function' is deprecated. Implementing 'Function' has no effect. Mixing in 'Function' is deprecatedDRT-W1300 Only a generic type, generic function, generic instance method, or generic constructor can have type argumentsDRT-W1301 Constructor already definedDRT-W1303 Duplicate declaration of nameDRT-W1304 Duplicate exportDRT-W1305 Multiple initializing parameters for the same field in a constructorDRT-W1306 Duplicate field name in record literal or type annotationDRT-W1307 Duplicate hidden nameDRT-W1308 Redundant ignore comment for diagnosticDRT-W1309 Duplicate named arguments in method invocationDRT-W1311 Duplicate assignment in pattern assignmentDRT-W1313 Duplicate field or getter in pattern matchingDRT-W1314 At most one rest element is allowed in a list or map patternDRT-W1315 Duplicate shown nameDRT-W1316 Duplicate variable declaration in logical-and patternDRT-W1317 A map pattern must have at least one entryDRT-W1318 A record literal without fields can't have a trailing commaDRT-W1319 The list of named fields in a record type can't be emptyDRT-W1320 A record type without fields can't have a trailing commaDRT-W1321 Empty subclass of 'Struct' or 'Union' is not supportedDRT-W1322 The name of the enum constant can't be the same as the enum's nameDRT-W1323 The invoked constructor isn't a 'const' constructorDRT-W1324 Mixins applied to enums can't have instance variablesDRT-W1325 Enum members should not be abstractDRT-W1326 The name 'values' is not a valid name for an enumDRT-W1327 Two elements in a constant set literal can't be equalDRT-W1328 Two elements in a set literal shouldn't be equalDRT-W1329 Two keys in a constant map literal can't be equalDRT-W1330 Classes can only extend other classesDRT-W1342 Two keys in a map literal shouldn't be equalDRT-W1331 Two keys in a map pattern can't be equalDRT-W1332 List patterns can have at most one type argumentDRT-W1333 List literals should have at most one type argumentDRT-W1334 Set literals should have at most one type argumentDRT-W1335 Expected two map pattern type argumentsDRT-W1336 Invalid number of type arguments in map literalDRT-W1337 Internal library can't be exportedDRT-W1338 Incompatible null safety between exported librariesDRT-W1339 Invalid export directive for a part fileDRT-W1340 Expressions can't be used in a map literalDRT-W1341 Extension can't be used as an expressionDRT-W1343 Conflicting instance and static members in an extensionDRT-W1344 Extensions can't declare abstract membersDRT-W1345 Extensions can't declare constructorsDRT-W1346 Extensions can't declare instance fieldsDRT-W1347 Extensions can't declare members with the same name as a member declared by 'Object'DRT-W1348 Extension override argument is not assignableDRT-W1350 An extension override can only be used to access instance membersDRT-W1351 Extension overrides have no value so they can't be used as the receiver of a cascade expressionDRT-W1352 External fields can't have initializers. External variables can't have initializersDRT-W1353 Fields in a struct class must have exactly one annotation indicating the native typeDRT-W1354 Too many positional argumentsDRT-W1355 Too many positional arguments for method with named parametersDRT-W1356 'Array's must have exactly one 'Array' annotationDRT-W1357 Duplicate field initialization in constructorDRT-W1358 Fields can't be initialized in the constructor if they are final and were already initialized at their declarationDRT-W1359 Fields can't be initialized in both the parameter list and the initializersDRT-W1360 Initializing formal parameters can't be used in factory constructorsDRT-W1361 Constructors in subclasses of 'Struct' and 'Union' can't have field initializersDRT-W1362 Incompatible type in field initializationDRT-W1363 Field formal parameters can only be used in a constructor. Initializing formal parameters can only be used in constructorsDRT-W1364 The redirecting constructor can't have a field initializerDRT-W1365 Incompatible types for field and initializing formal parameterDRT-W1366 Fields in subclasses of 'Struct' and 'Union' can't have initializersDRT-W1367 Duplicate initialization of final fieldDRT-W1369 Final variable must be initializedDRT-W1370 Functions marked 'async' must have a return type which is a supertype of 'Future'DRT-W1380 The compile-time constant expression depends on itselfDRT-W1583 Missing initialization for final instance fieldsDRT-W1371 Invalid element type in for-in loopDRT-W1373 Invalid type in for-in loopDRT-W1374 A for-in loop variable can't be a 'const'DRT-W1375 A method tear-off on a receiver whose type is 'dynamic' can't have type argumentsDRT-W1376 Generic subclasses of 'Struct' or 'Union' are not allowedDRT-W1377 Incompatible types for getter and setterDRT-W1378 Functions marked 'async*' must have a return type that is a supertype of 'Stream<T>' for some type 'T'DRT-W1379 Illegal concrete member in EnumDRT-W1381 Functions marked 'sync*' must have a return type that is a supertype of 'Iterable<T>' for some type 'T'DRT-W1383 Classes and mixins can only implement other classes and mixinsDRT-W1384 Duplicate class in 'implements' clauseDRT-W1385 Same class used in 'extends' and 'implements' or 'with' clausesDRT-W1386 Implicitly invoked unnamed constructor has missing required parametersDRT-W1387 Invalid reference to instance member in constructorDRT-W1388 The imported library defines a top-level function named 'loadLibrary' that is hidden by deferring this libraryDRT-W1389 Internal library can't be importedDRT-W1390 Unsafe import of legacy library into a null safe libraryDRT-W1391 Avoid importing part files directlyDRT-W1392 Conflicting method signatures in inherited classesDRT-W1393 Parts must have exactly the same language version override as the libraryDRT-W1394 Inconsistent type or finality of pattern variable in logical-orDRT-W1395 Non-existent field initialized in constructorDRT-W1396 Static field initialized in constructorDRT-W1397 Invalid initializing formal parameterDRT-W1398 Invalid access of static member through instanceDRT-W1399 Instance members can't be accessed from a factory constructorDRT-W1400 Instance members can't be accessed from a static methodDRT-W1401 Abstract classes can't be instantiatedDRT-W1402 Enums can't be instantiatedDRT-W1403 Type aliases that expand to a type parameter can't be instantiatedDRT-W1404 Integer literal imprecise as a doubleDRT-W1405 Annotation must be either a const variable reference or const constructor invocationDRT-W1407 Constant values from a deferred library can't be used in annotationsDRT-W1408 Constant values from a deferred library can't be used as annotationsDRT-W1409 Invalid annotation targetDRT-W1410 Incompatible types for variable assignmentDRT-W1411 Unsupported package dependencyDRT-W1412 The function 'main' can't have any required named parametersDRT-W1462 Invalid second argument for `Pointer.fromFunction` or `NativeCallable.isolateLocal` with certain return typesDRT-W1413 Invalid export of internal declarationDRT-W1414 Invalid export of internal element indirectlyDRT-W1415 Extension overrides must have exactly one argument: the value of 'this' in the extension methodDRT-W1416 Factory method must have a return typeDRT-W1417 Factory method doesn't return a newly allocated objectDRT-W1418 The name of a factory constructor must be the same as the name of the immediately enclosing classDRT-W1419 Prefer declaring const constructors on `@immutable` classesDRT-W1126 Record field names can't be a dollar sign followed by an integer when the integer is the index of a positional field. Record field names can't be private. Record field names can't be the same as a member from 'Object'DRT-W1420 Invalid field type in subclass of `Struct`DRT-W1421 Invalid concrete implementation of abstract methodDRT-W1422 Only public elements in a package's private API can be annotated as being internalDRT-W1424 Invalid Dart language version override comment formatDRT-W1425 Only const constructors can have the `@literal` annotationDRT-W1426 Invalid constructor modifierDRT-W1427 Setters can't use 'async', 'async*', or 'sync*'DRT-W1428 The annotation '@nonVirtual' can only be applied to a concrete instance memberDRT-W1429 Invalid usage of null-aware operators on non-nullable receiversDRT-W1430 Invalid method overrideDRT-W1431 Invalid throw expression typeDRT-W1643 Invalid override of member with '@nonVirtual' annotationDRT-W1432 Inconsistent variable declaration in switch statement casesDRT-W1433 The 'platforms' field must be a map with platforms as keysDRT-W1434 Generative enum constructors can only be used as targets of redirectionDRT-W1435 Invalid reference to 'this' expressionDRT-W1436 Incompatible return type in `Future.catchError` invocationDRT-W1437 The annotation '@sealed' can only be applied to classesDRT-W1438 Fields of type 'Array' must have exactly one 'Array' annotationDRT-W1482 Super parameters can only be used in non-redirecting generative constructorsDRT-W1439 Invalid type argument in constant list, map, or set literalDRT-W1440 Invalid URI syntaxDRT-W1441 Invalid use of `covariant` in extensionDRT-W1442 Reference to internal declaration outside the packageDRT-W1443 An expression whose value is always 'null' can't be dereferencedDRT-W1444 Invalid usage of class or mixin declaration modifiersDRT-W1445 Invalid use of visible for overriding memberDRT-W1446 A negation operand must have a static type of 'bool'DRT-W1507 Member annotated with `@visibleForTesting` used outside of testsDRT-W1447 Invalid use of visibility annotation on non-public declarationDRT-W1448 The annotation 'visibleForOverriding' can only be applied to a public instance member that can be overriddenDRT-W1449 The annotation 'visibleOutsideTemplate' can only be applied to a member of a class, enum, or mixin that is annotated with 'visibleForTemplate'DRT-W1450 Invocation of extension that doesn't define a `call` methodDRT-W1451 Invocation of a non-functionDRT-W1452 The expression doesn't evaluate to a function, so it can't be invokedDRT-W1453 Invalid label reference in outer methodDRT-W1454 Undefined labelDRT-W1455 Can't have a late final field in a class with a generative const constructorDRT-W1456 The late final local variable is already assignedDRT-W1457 FFI leaf call can't return a 'Handle'DRT-W1458 FFI leaf call can't take arguments of type 'Handle'DRT-W1459 Incompatible types in list literalDRT-W1460 The type of the first positional parameter of the 'main' function must be a supertype of 'List<String>'DRT-W1461 Invalid operand type for logical operatorDRT-W1508 The function 'main' can't have more than two required positional parametersDRT-W1463 The declaration named 'main' must be a functionDRT-W1464 Map entries can only be used in a map literalDRT-W1465 Invalid key type in map literalDRT-W1466 Incompatible value type in map literalDRT-W1467 The annotation doesn't match the declared type of the fieldDRT-W1468 Missing annotation for fields in subclasses of `Struct` or `Union`DRT-W1469 Missing default value for non-nullable optional parameterDRT-W1471 Missing dependency on imported packageDRT-W1472 Missing case clause for enum valuesDRT-W1473 Missing exceptional return value for method invocation in `dart:ffi`DRT-W1474 Fields in struct classes must have an explicitly declared type of 'int', 'double' or 'Pointer'DRT-W1475 The getter name is not specified explicitly, and the pattern is not a variableDRT-W1477 Missing concrete implementation of a `@mustBeOverridden` memberDRT-W1478 Missing required argumentDRT-W1479 Missing required parameterDRT-W1480 Implicit return at the end of function or methodDRT-W1481 Use adjacent strings to concatenate string literalsDRT-W1120 Missing variable pattern in one branch of logical-or patternDRT-W1483 Mismatched method signature in mixin invocationDRT-W1484 Invalid mixin applicationDRT-W1485 Missing concrete implementation of super-invoked memberDRT-W1486 Mixin class can only extend `Object`DRT-W1487 Invalid use of class with constructor as a mixinDRT-W1488 Mixin class extends a class other than `Object`DRT-W1489 Mixins can't be instantiatedDRT-W1490 Classes can only mix in mixins and classesDRT-W1491 Mixin constraint is sealed and can't be usedDRT-W1492 Use `isNotEmpty` for Iterables and MapsDRT-W1148 Only classes and mixins can be used as superclass constraintsDRT-W1494 Constructors can have only one 'this' redirection, at mostDRT-W1495 A constructor can have at most one 'super' initializerDRT-W1496 Invalid type argument for FFI invocationDRT-W1497 Function type must be a subtype of the type argument in FFI invocationDRT-W1498 Immutable class defines non-final instance fieldsDRT-W1499 Missing invocation of overridden methodDRT-W1500 Function passed to 'NativeCallable.listener' must return 'void'DRT-W1501 The value of the 'name' field is required to be a stringDRT-W1502 Undefined unnamed constructorDRT-W1503 Missing concrete implementation of abstract member(s)DRT-W1504 Conditions must have a static type of 'bool'DRT-W1505 Annotation creation can only call a const constructorDRT-W1509 Avoid library directives unless they have documentation comments or annotationsDRT-W1181 Avoid null in null-aware assignmentDRT-W1183 Case expressions must be constantDRT-W1510 Constant values from a deferred library can't be used as a case expressionDRT-W1511 The default value of an optional parameter must be constantDRT-W1512 Constant values from a deferred library can't be used as a default parameter valueDRT-W1513 Use generic function type syntax for parametersDRT-W1199 The values in a const list literal must be constantsDRT-W1514 The elements in a const map literal must be constantDRT-W1515 The keys in a const map literal must be constantDRT-W1516 Key expressions in map patterns must be constantsDRT-W1517 The values in a const map literal must be constantDRT-W1518 The relational pattern expression must be a constantDRT-W1519 The values in a const set literal must be constantsDRT-W1520 Invalid use of type parameter as a type argumentDRT-W1521 Inherited member is always abstract in the supertypeDRT-W1217 Missing `const` keyword when invoking a constructor with `@literal` annotationDRT-W1522 Generative enum constructors must be 'const'DRT-W1523 Spread elements in map literals must implement 'Map'DRT-W1544 Non-exhaustive switch expression over an exhaustive typeDRT-W1524 Non-exhaustive switch statement over an exhaustive typeDRT-W1525 Non generative constructor in initializer listDRT-W1527 Implicit generative constructor in subclass cannot invoke explicit unnamed factory constructor in superclassDRT-W1528 Invalid C function signature for 'asFunction' invocationDRT-W1529 Array dimensions must be positive numbersDRT-W1530 Invalid type argument for class `Array`DRT-W1531 Factory bodies can't use 'async', 'async*', or 'sync*'DRT-W1532 Invalid use of non-type identifier as type argumentDRT-W1533 The return type of the operator []= must be 'void'DRT-W1535 The return type of the setter must be 'void' or absentDRT-W1536 Non-nullable local variable must be assigned before useDRT-W1537 Invalid use of unary operator as a binary operatorDRT-W1539 Uninitialized non-nullable instance fieldDRT-W1541 Non-nullable variables must be initializedDRT-W1542 Spread elements in list or set literals must implement 'Iterable'DRT-W1543 Cannot infer missing types from overridden methodsDRT-W1546 Invalid superclass for class with generative constructorsDRT-W1547 A potentially nullable type can't be used in an 'on' clause because it isn't valid to throw a nullable expressionDRT-W1548 A class can't extend a nullable typeDRT-W1549 A class or mixin can't implement a nullable typeDRT-W1550 A mixin can't have a nullable type as a superclass constraintDRT-W1551 Invalid null argument for non-nullable type argumentDRT-W1553 Keys in the `platforms` field can't have valuesDRT-W1571 This null-check will always throw an exception because the expression will always evaluate to 'null'DRT-W1554 Using a colon as the separator before a default value is no longer supportedDRT-W1555 Duplicate superclass constraint in mixinDRT-W1556 Optional parameters aren't allowed when defining an operatorDRT-W1557 The field doesn't override an inherited getter or setter. The getter doesn't override an inherited getter. The method doesn't override an inherited method. The setter doesn't override an inherited setterDRT-W1558 Structs must have at most one 'Packed' annotationDRT-W1559 Only packing to 1, 2, 4, 8, and 16 bytes is supportedDRT-W1560 Avoid including a file from a different library as a part of itselfDRT-W1561 Missing part-of directive in included fileDRT-W1562 Invalid 'part of' directive in unnamed libraryDRT-W1563 Dependency path does not existDRT-W1564 Dependencies defined must be a mapDRT-W1294 Dependency path isn't a POSIX-style pathDRT-W1565 Missing 'pubspec.yaml' file in directoryDRT-W1566 Only local variables can be assigned in pattern assignmentsDRT-W1567 Constant values from a deferred library can't be used in patternsDRT-W1568 Mismatched value type in pattern assignment or declarationDRT-W1569 Pattern variables can't be assigned inside the guard of the enclosing guarded patternDRT-W1570 Positional super parameters can't be used when the super constructor invocation has a positional argumentDRT-W1573 Name conflict between import prefix and top-level declarationDRT-W1574 Import prefix must be followed by `.`DRT-W1575 Prefix shadowed by a local declarationDRT-W1576 Conflicting private member names in mixinsDRT-W1577 Private setter used in a libraryDRT-W1579 Duplicate importDRT-W1310 A record literal with exactly one positional field requires a trailing commaDRT-W1581 A record type with exactly one positional field requires a trailing commaDRT-W1582 Constructors can't redirect to themselves either directly or indirectlyDRT-W1584 Circular type hierarchyDRT-W1585 Redirected constructor is undefinedDRT-W1586 Generative constructors can't redirect to a factory constructorDRT-W1587 Fields of 'Struct' and 'Union' subclasses must be marked externalDRT-W1368 Invalid declaration of 'values' in a class that implements 'Enum'DRT-W1382 Non-type in catch clauseDRT-W1534 A class or mixin can't mix in a nullable typeDRT-W1552 Object patterns can only use named fieldsDRT-W1572 Final variable can't be read because it's potentially unassigned at this pointDRT-W1580 The prefix of a deferred import can't be used in other import directivesDRT-W1620 Undefined name in type test expressionDRT-W1652 Undefined enum constantDRT-W1657 Unnecessary '?' for nullable typesDRT-W1686 Relational pattern operand type not assignable to operator parameter typeDRT-W1597 The redirecting constructor can't have a 'super' initializerDRT-W1637 Invalid name in hide combinator for imported libraryDRT-W1665 Redirect to abstract class constructorDRT-W1588 Incompatible parameters in redirected constructorsDRT-W1589 Invalid return type in factory constructor redirectionDRT-W1590 Redirect to missing constructorDRT-W1591 Invalid redirect in a redirected constructorDRT-W1592 A constant redirecting constructor can't redirect to a non-constant constructorDRT-W1593 A redirecting constructor can't redirect to a type alias that expands to a type parameterDRT-W1594 Variable referenced before declarationDRT-W1595 Refutable patterns can't be used in an irrefutable contextDRT-W1596 The return type of operators used in relational patterns must be assignable to 'bool'DRT-W1598 A map pattern can't contain a rest patternDRT-W1599 A rethrow must be inside of a catch clauseDRT-W1600 Constructors can't return valuesDRT-W1601 Can't return a value from a generator function that uses the 'async*' or 'sync*' modifierDRT-W1602 Invalid return of value annotated with `doNotStore`DRT-W1603 Return value type mismatchDRT-W1604 The return value is missing after 'return'DRT-W1606 Missing import for 'Future' and 'Stream' classes in lower version SDKsDRT-W1607 The use of an as expression in a constant expression wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versionsDRT-W1608 Invalid use of boolean operators in constant contextDRT-W1609 Tearing off a constructor requires the 'constructor-tearoffs' language featureDRT-W1610 Using the operator '==' for non-primitive types wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versionsDRT-W1611 Extension methods weren't supported until version 2.6.0, but this code is required to be able to run on earlier versionsDRT-W1612 The operator '>>>' wasn't supported until version 2.14.0, but this code is required to be able to run on earlier versionsDRT-W1613 The use of an is expression in a constant context wasn't supported until version 2.3.2, but this code is required to be able to run on earlier versionsDRT-W1614 The type 'Never' wasn't supported until version 2.12.0, but this code is required to be able to run on earlier versionsDRT-W1615 Set literals weren't supported until version 2.2, but this code is required to be able to run on earlier versionsDRT-W1616 The for, if, and spread elements weren't supported until version 2.3.0, but this code is required to be able to run on earlier versionsDRT-W1617 The if and spread elements weren't supported in constant expressions until version 2.5.0, but this code is required to be able to run on earlier versionsDRT-W1618 Element can't be assigned to the setDRT-W1619 'Array's must have an 'Array' annotation that matches the dimensionsDRT-W1621 Invalid use of static access to instance memberDRT-W1622 Subtype of `base` or `final` is not `base`, `final` or `sealed`DRT-W1623 Classes and mixins can't implement deferred classes. Classes can't extend deferred classes. Classes can't mixin deferred classesDRT-W1624 Cannot extend or implement FFI classes other than 'Struct' or 'Union'DRT-W1626 Avoid extending, mixing in, or implementing sealed class outside of the same packageDRT-W1627 A type alias that expands to a type parameter can't be implemented. A type alias that expands to a type parameter can't be mixed in. A type alias that expands to a type parameter can't be used as a superclass constraint. A type alias that expands to a type parameter can't be used as a superclassDRT-W1629 Mismatched parameter type in super constructorDRT-W1630 No associated named super constructor parameterDRT-W1631 Undefined or inaccessible methodDRT-W1668 No associated positional super constructor parameterDRT-W1632 Super invocation not at the end of initializer listDRT-W1633 The enum constructor can't have a 'super' initializerDRT-W1634 The 'super' keyword can't be used in an extension because an extension doesn't have a superclassDRT-W1635 Invalid context for 'super' invocationDRT-W1636 The 'case' shouldn't complete normallyDRT-W1638 Incompatible types in switch statementDRT-W1639 A generative constructor of an abstract class can't be torn offDRT-W1640 Text direction Unicode code points in literalDRT-W1642 Self-referencing variables with no type annotationDRT-W1644 Typedefs can't reference themselves directly or recursively via another typedefDRT-W1645 Deferred type can't be used in a declaration, cast, or type testDRT-W1646 Type argument not matching boundsDRT-W1647 Tests for non-null should be done with '!= null'. Tests for null should be done with '== null'DRT-W1648 Static members can't reference type parameters of the classDRT-W1649 Type parameter bound is redundantDRT-W1650 Non-type used in an 'is' expressionDRT-W1651 Nullable expression used without null checkDRT-W1653 Undefined annotationDRT-W1654 Class is undefinedDRT-W1655 Missing or invalid superclass constructor invocationDRT-W1656 Enum doesn't have an unnamed constructorDRT-W1658 Undefined getter for extensionDRT-W1659 Unnecessary dev dependencyDRT-W1678 Undefined method for extensionDRT-W1660 Undefined operator for extensionDRT-W1661 Undefined setter in extensionDRT-W1662 Undefined functionDRT-W1663 Undefined or invisible getterDRT-W1664 Undefined identifierDRT-W1666 Undefined name 'await' in function body not marked with 'async'DRT-W1667 Unused local variableDRT-W1698 Undefined named parameter in method or function invocationDRT-W1669 Undefined operatorDRT-W1670 Identifier not defined the imported libraryDRT-W1671 Undefined parameter name in `UseResult.unless` annotationDRT-W1672 Undefined setterDRT-W1673 Invalid name in show combinator for imported libraryDRT-W1674 Undefined super memberDRT-W1675 Unrecognized platform name in `pubspec.yaml`DRT-W1676 Unnecessary castDRT-W1677 Invalid number of parameters in operator declarationDRT-W1709 Unnecessary importDRT-W1679 A double can't equal 'double.nan', so the condition is always 'false'. A double can't equal 'double.nan', so the condition is always 'true'DRT-W1680 The '!' will have no effect because the receiver can't be nullDRT-W1681 Unnecessary 'noSuchMethod' declarationDRT-W1682 The null-assert pattern will have no effect because the matched type isn't nullableDRT-W1683 The operand can't be null, so the condition is always 'false'. The operand can't be null, so the condition is always 'true'DRT-W1685 Braces unnecessarily wrap this expression in a set literalDRT-W1687 Unnecessary type check; the result is always 'false'. Unnecessary type check; the result is always 'true'DRT-W1688 Static members from supertypes must be qualified by the name of the defining typeDRT-W1689 Static members from the extended type or one of its superclasses must be qualified by the name of the defining typeDRT-W1690 This case is covered by the previous casesDRT-W1691 Unused exception variable in catch clauseDRT-W1692 Unused stack trace parameter in catch blockDRT-W1693 Unused private declarationDRT-W1694 Unused private fieldDRT-W1695 Remove unused importDRT-W1696 Unused labelDRT-W1697 Unused result of `useResult` annotated functionDRT-W1699 Unused name in show combinatorDRT-W1700 Invalid file referenceDRT-W1701 Target URI hasn't been generatedDRT-W1702 URIs can't use string interpolationDRT-W1703 Dart native extensions are deprecated and aren't available in Dart 2.15DRT-W1704 This expression has a type of 'void' so its value can't be usedDRT-W1705 A member named 'values' can't be declared in an enumDRT-W1706 Variable patterns in declaration context can't specify 'var' or 'final' keywordDRT-W1707 Invalid type assignment in constant expressionDRT-W1708 Setters must declare exactly one required positional parameterDRT-W1710 Wrong number of type parameters and type argumentsDRT-W1711 Invalid placement of type arguments in named constructorDRT-W1712 Wrong number of type arguments provided for enum constantDRT-W1713 Wrong number of type parameters and type arguments in extensionDRT-W1714 Wrong number of type parameters and type arguments in methodDRT-W1715 Mismatch between yielded value type and return typeDRT-W1717 Incompatible return type for closureDRT-W1605 Restricted classes used in inheritance and implementation clausesDRT-W1625 Invalid transitive inheritance of `Struct`, `Union` or `AbiSpecificInteger` classDRT-W1628 Text direction Unicode code points in commentDRT-W1641 The null-check pattern will have no effect because the matched type isn't nullableDRT-W1684 Yield statements must be in a generator function (one marked with either 'async*' or 'sync*'). Yield-each statements must be in a generator function (one marked with either 'async*' or 'sync*')DRT-W1716

Dart Analyze/

DRT-W1430

Invalid usage of null-aware operators on non-nullable receiversDRT-W1430

Major

Bug Risk

The analyzer produces this diagnostic when a null-aware operator (?., ?.., ?[, ?..[, or ...?) is used on a receiver that's known to be non-nullable.

Examples

The following code produces this diagnostic because s can't be null:

int? getLength(String s) {
  return s?.length;
}

The following code produces this diagnostic because a can't be null:

var a = [];
var b = [...?a];

The following code produces this diagnostic because s?.length can't return null:

void f(String? s) {
  s?.length?.isEven;
}

The reason s?.length can't return null is because the null-aware operator following s short-circuits the evaluation of both length and isEven if s is null. In other words, if s is null, then neither length nor isEven will be invoked, and if s is non-null, then length can't return a null value. Either way, isEven can't be invoked on a null value, so the null-aware operator isn't necessary. See Understanding null safety for more details.

The following code produces this diagnostic because s can't be null.

void f(Object? o) {
  var s = o as String;
  s?.length;
}

The reason s can't be null, despite the fact that o can be null, is because of the cast to String, which is a non-nullable type. If o ever has the value null, the cast will fail and the invocation of length will not happen.

Common fixes

Replace the null-aware operator with a non-null-aware equivalent; for example, change ?. to .:

int getLength(String s) {
  return s.length;
}

(Note that the return type was also changed to be non-nullable, which might not be appropriate in some cases.)