fix(linter): allow eslintrc to add rule when overriding (#1984)

Fix a bug introduced in https://github.com/oxc-project/oxc/pull/1966.
Ideally, the rules in eslintrc should be merged into final rules as
described:

> The rules will start with the categories we apply, and then merge all
the configurations stated in the rules field.
>
> For example, if we begin with -D correctness with 80 rules, then
>
> "no-empty-file": "off" will remove the rule, yielding 79 rules
> "no-empty": "error" (restriction) will add the rule, yield 81 rules
> ""no-empty": ["error", { "allowEmptyCatch": true }]` add the rule's
configuration

However, the implementation did not include the newly added rules in the
eslintrc. As a test case and example, I added a new fixture to
`crates/oxc_cli/fixtures/no_undef`. No warn or deny will be found
without this PR.

This is my first Rust PR ever. Any nitpicking suggestions are welcome.
Thanks! 😊

crates/oxc_cli/fixtures/no_undef/eslintrc.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "no-undef": "warn"
+  }
+}

crates/oxc_cli/fixtures/no_undef/test.js

@@ -0,0 +1 @@
+console.log()

crates/oxc_cli/src/lint/mod.rs

@@ -324,6 +324,15 @@ mod test {
         assert_eq!(result.number_of_errors, 0);
     }
 
+    #[test]
+    fn eslintrc_no_undef() {
+        let args = &["-c", "fixtures/no_undef/eslintrc.json", "fixtures/no_undef/test.js"];
+        let result = test(args);
+        assert_eq!(result.number_of_files, 1);
+        assert_eq!(result.number_of_warnings, 1);
+        assert_eq!(result.number_of_errors, 0);
+    }
+
     #[test]
     fn no_empty_allow_empty_catch() {
         let args = &[

crates/oxc_linter/src/config/mod.rs

@@ -68,14 +68,20 @@ impl ESLintConfig {
         })
     }
 
-    pub fn override_rules(&self, rules_to_override: &mut FxHashSet<RuleEnum>) {
+    pub fn override_rules(
+        &self,
+        rules_to_override: &mut FxHashSet<RuleEnum>,
+        all_rules: &[RuleEnum],
+    ) {
         let mut rules_to_replace = vec![];
         let mut rules_to_remove = vec![];
-        for rule in rules_to_override.iter() {
-            let plugin_name = rule.plugin_name();
-            let rule_name = rule.name();
-            if let Some(rule_to_configure) =
-                self.rules.iter().find(|r| r.plugin_name == plugin_name && r.rule_name == rule_name)
+
+        for rule_to_configure in &self.rules {
+            let (plugin_name, rule_name) =
+                (&rule_to_configure.plugin_name, &rule_to_configure.rule_name);
+            if let Some(rule) = rules_to_override
+                .iter()
+                .find(|r| r.plugin_name() == plugin_name && r.name() == rule_name)
             {
                 match rule_to_configure.severity {
                     AllowWarnDeny::Warn | AllowWarnDeny::Deny => {
@@ -85,8 +91,13 @@ impl ESLintConfig {
                         rules_to_remove.push(rule.clone());
                     }
                 }
+            } else if let Some(rule) =
+                all_rules.iter().find(|r| r.plugin_name() == plugin_name && r.name() == rule_name)
+            {
+                rules_to_replace.push(rule.read_json(rule_to_configure.config.clone()));
             }
         }
+
         for rule in rules_to_remove {
             rules_to_override.remove(&rule);
         }

crates/oxc_linter/src/options.rs

@@ -199,7 +199,7 @@ impl LintOptions {
         }
 
         if let Some(config) = &config {
-            config.override_rules(&mut rules);
+            config.override_rules(&mut rules, &all_rules);
         }
 
         let mut rules = rules.into_iter().collect::<Vec<_>>();