perf(linter): only generate cfg when we have a rule which depends on it.

crates/oxc_language_server/src/linter.rs

@@ -285,10 +285,12 @@ impl IsolatedLintHandler {
                 return Some(Self::wrap_diagnostics(path, &original_source_text, reports, start));
             };
 
+            let use_cfg = linter.rules().iter().any(|it| it.rule.use_cfg());
+
             let program = allocator.alloc(ret.program);
             let semantic_ret = SemanticBuilder::new(javascript_source_text, source_type)
                 .with_trivias(ret.trivias)
-                .with_cfg(true)
+                .with_cfg(use_cfg)
                 .with_check_syntax_error(true)
                 .build(program);
 

crates/oxc_linter/src/lib.rs

@@ -62,6 +62,10 @@ impl Default for Linter {
 }
 
 impl Linter {
+    pub fn rules(&self) -> &Vec<RuleWithSeverity> {
+        &self.rules
+    }
+
     /// # Errors
     ///
     /// Returns `Err` if there are any errors parsing the configuration file.

crates/oxc_linter/src/service.rs

@@ -265,10 +265,12 @@ impl Runtime {
 
         let trivias = ret.trivias;
 
+        let use_cfg = self.linter.rules.iter().any(|it| it.rule.use_cfg());
+
         // Build the module record to unblock other threads from waiting for too long.
         // The semantic model is not built at this stage.
         let semantic_builder = SemanticBuilder::new(source_text, source_type)
-            .with_cfg(true)
+            .with_cfg(use_cfg)
             .with_trivias(trivias)
             .with_check_syntax_error(check_syntax_errors)
             .build_module_record(path.to_path_buf(), program);