fix: support index expressions for no-magic-number rule (#755)

Author: incendial

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+* fix: support index expressions for no-magic-number rule.
+
 ## 4.13.0
 
 * feat: add [Checkstyle](https://dartcodemetrics.dev/docs/cli/analyze#checkstyle) format reporter.
@@ -67,7 +71,7 @@
 
 * feat: add static code diagnostics [`avoid-global-state`](https://dartcodemetrics.dev/docs/rules/common/avoid-global-state), [`avoid-unrelated-type-assertions`](https://dartcodemetrics.dev/docs/rules/common/avoid-unrelated-type-assertions).
 * feat: support extensions and static getters for [`check-unused-l10n`](https://dartcodemetrics.dev/docs/cli/check-unused-l10n).
-* feat: improve [ `prefer-correct-type-name`](https://dartcodemetrics.dev/docs/rules/common/prefer-correct-type-name), [`prefer-match-file-name`](https://dartcodemetrics.dev/docs/rules/common/prefer-match-file-name) rules.
+* feat: improve [prefer-correct-type-name](https://dartcodemetrics.dev/docs/rules/common/prefer-correct-type-name), [`prefer-match-file-name`](https://dartcodemetrics.dev/docs/rules/common/prefer-match-file-name) rules.
 * feat: add `delete-files` flag to [`check-unused-files`](https://dartcodemetrics.dev/docs/cli/check-unused-files) command.
 * feat: facelift console reporters.
 * chore: restrict `analyzer` version to `>=2.4.0 <3.1.0`.

lib/src/analyzers/lint_analyzer/rules/rules_list/no_magic_number/no_magic_number_rule.dart

@@ -43,6 +43,7 @@ class NoMagicNumberRule extends CommonRule {
         .where(_isNotInsideConstMap)
         .where(_isNotInsideConstConstructor)
         .where(_isNotInDateTime)
+        .where(_isNotInsideIndexExpression)
         .map((lit) => createIssue(
               rule: this,
               location: nodeLocation(
@@ -86,4 +87,6 @@ class NoMagicNumberRule extends CommonRule {
       l.thisOrAncestorMatching((ancestor) =>
           ancestor is InstanceCreationExpression && ancestor.isConst) ==
       null;
+
+  bool _isNotInsideIndexExpression(Literal l) => l.parent is! IndexExpression;
 }

test/src/analyzers/lint_analyzer/rules/rules_list/no_magic_number/examples/exceptions_example.dart

@@ -1,12 +1,24 @@
-int good_f1(int x) => x + 1;
-bool good_f2(int x) => x != 0;
-bool good_f3(String x) => x.indexOf(str) != -1;
-final someDay = DateTime(2006, 12, 1);
-final anotherDay = DateTime.utc(2006, 12, 1);
-final f = Intl.message(example: const <String, int>{'Assigned': 3});
-final f = foo(const [32, 12]);
-final f = Future.delayed(const Duration(seconds: 5));
-final f = foo(const Bar(5));
-final number = 500;
-var number = 500;
-var numbers = [100, 200, 300];
+void main() {
+  int good_f1(int x) => x + 1;
+  bool good_f2(int x) => x != 0;
+  bool good_f3(String x) => x.indexOf(str) != -1;
+  final someDay = DateTime(2006, 12, 1);
+  final anotherDay = DateTime.utc(2006, 12, 1);
+  final f = Intl.message(example: const <String, int>{'Assigned': 3});
+  final f = foo(const [32, 12]);
+  final f = Future.delayed(const Duration(seconds: 5));
+  final f = foo(const Bar(5));
+  final number = 500;
+  var number = 500;
+  var numbers = [100, 200, 300];
+  numbers[0];
+
+  Map<int, String> m = {
+    1: '',
+    2: '',
+    3: '',
+  };
+  String? mv = m[2];
+  final mf = m[2];
+  print(m[2]);
+}