From fd5edb71b5e38d2478f6fe44938586ad1379684f Mon Sep 17 00:00:00 2001
From: Cam McHenry <camchenry@users.noreply.github.com>
Date: Wed, 28 Oct 2026 23:07:02 -0400
Subject: [PATCH] perf(linter/import/no-cycle): reuse module records in
 diagnostic stack (#27480)

Instead of storing copies of paths, we store a reference to the original
module record, which has the path we need. By doing this, we don't need
to repeatedly clone lots of paths, but we now need to do a lot more
reference counting, but I think it's a good tradeoff.

Running on `vscode`:


Metric | Before | After | Change
-- | -- | -- | --
Allocation calls | 19,051,530 | 16,807,784 | -11.8%
Allocated bytes | 1,700,223,977 B | 1,506,926,944 B | -11.4%

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 crates/oxc_linter/src/rules/import/no_cycle.rs | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/crates/oxc_linter/src/rules/import/no_cycle.rs b/crates/oxc_linter/src/rules/import/no_cycle.rs
index 49c1a0f567..4614ac3b5b 100644
--- a/crates/oxc_linter/src/rules/import/no_cycle.rs
+++ b/crates/oxc_linter/src/rules/import/no_cycle.rs
@@ -1,6 +1,6 @@
 use std::{
     ffi::OsStr,
-    path::{Component, Path, PathBuf},
+    path::{Component, Path},
     sync::Arc,
 };
 
@@ -20,7 +20,11 @@ use crate::{
     rule::{DefaultRuleConfig, Rule},
 };
 
-fn no_cycle_diagnostic(span: Span, stack: &[(CompactStr, PathBuf)], cwd: &Path) -> OxcDiagnostic {
+fn no_cycle_diagnostic(
+    span: Span,
+    stack: &[(CompactStr, Arc<ModuleRecord>)],
+    cwd: &Path,
+) -> OxcDiagnostic {
     let cycle_description = format_cycle(stack, cwd);
     OxcDiagnostic::warn("Dependency cycle detected")
         .with_help("Refactor to remove the cycle. Consider extracting shared code into a separate module that both files can import.")
@@ -38,10 +42,11 @@ fn self_referencing_cycle_diagnostic(span: Span, is_import: bool) -> OxcDiagnost
         .with_label(span.primary_label("this module references itself"))
 }
 
-fn format_cycle(stack: &[(CompactStr, PathBuf)], cwd: &Path) -> String {
+fn format_cycle(stack: &[(CompactStr, Arc<ModuleRecord>)], cwd: &Path) -> String {
     let mut lines = Vec::with_capacity(stack.len() * 2 + 1);
 
-    for (i, (specifier, path)) in stack.iter().enumerate() {
+    for (i, (specifier, module_record)) in stack.iter().enumerate() {
+        let path = &module_record.resolved_absolute_path;
         let relative_path = path
             .strip_prefix(cwd)
             .unwrap_or(path)
@@ -169,8 +174,7 @@ impl Rule for NoCycle {
 
             let requested_module = module_record.requested_modules[&key][0];
             let span = requested_module.span;
-            let mut stack =
-                vec![(key.clone(), loaded_module_record.resolved_absolute_path.clone())];
+            let mut stack = vec![(key.clone(), Arc::clone(&loaded_module_record))];
 
             if loaded_module_record.resolved_absolute_path == *needle {
                 ctx.diagnostic(self_referencing_cycle_diagnostic(span, requested_module.is_import));
@@ -182,7 +186,7 @@ impl Rule for NoCycle {
                 .filter(|(key, val), parent| self.should_traverse_module(key, val, parent))
                 .event(|event, (key, val), _| match event {
                     ModuleGraphVisitorEvent::Enter => {
-                        stack.push((key.clone(), val.resolved_absolute_path.clone()));
+                        stack.push((key.clone(), Arc::clone(val)));
                     }
                     ModuleGraphVisitorEvent::Leave => {
                         stack.pop();