test: re-enable the LeakSanitizer exit check for the bake dev tests that no longer leak

[robobun]

Problem

• test/no-validate-leaksan.txt switches off the ASAN lane's exit-time leak check for the files it lists. Its two bake blocks listed ten dev server test files: the "Watcher Thread" block (entries excluded since the check was wired into CI in ci: instrument being able to run leaksanitizer #21142, grouped under that heading in a09dc2f) and the "leaks related to the dev server closing on process exit" block (ssg 3 #22138). Those files have never run under the check.
• Eight of the ten no longer leak. Run on current main under exactly the environment the runner sets for checked files (scripts/runner.node.mjs: BUN_DESTRUCT_VM_ON_EXIT=1, ASAN_OPTIONS=...detect_leaks=1..., LSAN_OPTIONS=...suppressions=test/leaksan.supp), dev-and-prod, dev/esm, dev/hot, dev/react-spa, dev/sourcemap, dev/ssg-pages-router, dev/react-response and dev/server-sourcemap exit 0 with no LeakSanitizer output, 4 of 4 runs each (table below).
• The other two still fail the check, each for one known leak that has a fix in flight, and the old comments did not say so:
  • dev/bundle.test.ts, "removing 'use client' from a component with a pending resolution failure": Direct leak of 336 byte(s) from BundleV2::enqueue_server_component_generated_file (src/bundler/bundle_v2.rs:3752), the ServerComponentParseTask bundler: free the ServerComponentParseTask after it generates its file #38004 frees. The other 20 cases in the file are clean.
  • dev/css.test.ts, "changing html file with link tag works" and "css import before create": Direct leak of 30 byte(s) from Watcher::add_directory via DirectoryWatchStore::insert (src/runtime/bake/dev_server/mod.rs:1447), the evicted watch entry path watcher: free the owned path of evicted watchlist entries #39197 frees. The other 13 cases are clean.
• Three entries name files that do not exist, so they have never excluded anything: test/bake/dev/deinitialization.test.ts (the file is test/bake/deinitialization.test.ts; no file ever existed at the listed path), test/bake/dev/react-cookies.test.ts (added in the same commit as request-cookies.test.ts, which is the file that exists), and test/cli/install/bun-repl.test.ts (deleted in fa3a30f). The two real files have been running under the check in CI all along; bake: fix use-after-free in ~DevServerSourceProvider during VM teardown #34035 is a CI failure of request-cookies.test.ts under BUN_DESTRUCT_VM_ON_EXIT.

Fix

• Remove the eight clean files and the three dead entries; CI's ASAN lane now applies the exit-time check to the eight files (this PR's own ASAN run is the first one that does).
• Keep bundle.test.ts and css.test.ts, under a comment that names the leaking case in each, the allocation site and size, and the PR that fixes it, so each entry can be removed with its fix. watcher: free the owned path of evicted watchlist entries #39197 already removes the css.test.ts line on its branch; whichever lands second needs a one-line rebase of this block. bundler: free the ServerComponentParseTask after it generates its file #38004 does not touch this file, so bundle.test.ts should be removed when it lands.
• Removing an entry is correct when the file passes under the runner's environment: that environment is the only thing the list controls. The removed files were verified on a debug ASAN build, which checks the same allocations as the release ASAN build CI uses. The positive control is the same harness and environment reporting the css.test.ts and bundle.test.ts leaks above from inside the dev server child processes, so a clean run means the check ran and found nothing, not that it was skipped.
• Not touched: dev/production.test.ts (bun build --app still leaks its transpilers, bake: drop the production build's transpilers and framework projection #38233; bake: exit a successful bun build --app through the build VM #38241 documents that entry) and the bake files listed in the generic blocks near the top of the file (ecosystem, html, plugins, stress, vfile, import-meta-inline, incremental-graph-edge-deletion), which were not audited here.
• Verified: every file in the diff was run with ./build/debug/bun-debug test <file> under the three variables above, on main at f0f6b2c. Results are in the table below. Every non-vendor/ entry remaining in the file exists on disk.

Background

• LeakSanitizer (LSan) is part of the ASAN build. At process exit it reports heap blocks nothing points to any more; with abort_on_error=1 a report aborts the process. Bun disables it by default; scripts/runner.node.mjs turns it back on for every test file not in test/no-validate-leaksan.txt and also sets BUN_DESTRUCT_VM_ON_EXIT=1, which tears the JSC VM down before exit so memory still owned by live JS objects is freed rather than reported.
• The bake tests spawn one dev server process per test case (test/bake/bake-harness.ts). The test process's environment is inherited, so the check runs in each dev server process: at the end of a case the harness stops the server, waits until DevServer has been dropped, and calls process.exit(0); a leak report there makes the server exit by SIGABRT and the case fails with DevServer exited with signal SIGABRT. This is how the two remaining entries fail, and the leak coverage the removed entries were withholding.
• The list also decides which files the runner may batch into its parallel bucket on the ASAN lane (isBucketCandidate requires the file to be leak-checked); sourcemap, react-response and server-sourcemap become eligible there, as they already are on the other lanes.

Probe results (debug ASAN build of main at f0f6b2c, runner environment)

file	runs	result
test/bake/dev-and-prod.test.ts	4	12 pass, exit 0, no LSan output, every run
test/bake/dev/esm.test.ts	4	17 pass, exit 0, no LSan output, every run
test/bake/dev/hot.test.ts	4	11 pass, exit 0, no LSan output, every run
test/bake/dev/react-spa.test.ts	4	6 pass, exit 0, no LSan output, every run
test/bake/dev/sourcemap.test.ts	4	2 pass, exit 0, no LSan output, every run
test/bake/dev/ssg-pages-router.test.ts	4	9 pass, exit 0, no LSan output, every run
test/bake/dev/react-response.test.ts	4	11 pass, exit 0, no LSan output, every run
test/bake/dev/server-sourcemap.test.ts	4	5 pass, exit 0, no LSan output, every run
test/bake/deinitialization.test.ts (never actually excluded)	1	pass, exit 0, no LSan output
test/bake/dev/request-cookies.test.ts (never actually excluded)	1	2 pass, exit 0, no LSan output
test/bake/dev/bundle.test.ts (kept)	1	20 pass, 1 fail: the 336 byte ServerComponentParseTask report
test/bake/dev/css.test.ts (kept)	1	13 pass, 2 fail: one 30 byte Watcher::add_directory report each

Cost of the check on the debug build: sourcemap.test.ts 11s without the environment, 18s with it; dev-and-prod.test.ts (12 dev server processes) 37s and 79s. The existing checked bake files show the release ASAN equivalent in test/expected-durations.json (deinitialization.test.ts: 2.2s default, 8.0s asan).

Leak report from bundle.test.ts, bun frames only:

Direct leak of 336 byte(s) in 1 object(s) allocated from:
    <alloc::boxed::Box<bun_bundler::ServerComponentParseTask::ServerComponentParseTask>>::new
    <bun_bundler::bundle_v2::BundleV2>::enqueue_server_component_generated_file src/bundler/bundle_v2.rs:3752
    <bun_bundler::bundle_v2::BundleV2>::on_parse_task_complete src/bundler/bundle_v2.rs:7219
    bun_bundler::parse_task::parse_worker::on_complete src/bundler/ParseTask.rs:2935
SUMMARY: AddressSanitizer: 336 byte(s) leaked in 1 allocation(s).

Leak report from css.test.ts (css-13; css-14 is identical), bun frames only:

Direct leak of 30 byte(s) in 1 object(s) allocated from:
    <bun_watcher::watcher_impl::Watcher>::append_directory_assume_capacity::<true> src/watcher/Watcher.rs:616
    <bun_watcher::watcher_impl::Watcher>::add_directory::<true> src/watcher/Watcher.rs:802
    <bun_runtime::bake::dev_server::DirectoryWatchStore>::insert src/runtime/bake/dev_server/mod.rs:1447
    <bun_runtime::bake::dev_server::DirectoryWatchStore>::track_resolution_failure src/runtime/bake/dev_server/mod.rs:1313
    <bun_bundler::bundle_v2::BundleV2>::resolve_import_records src/bundler/bundle_v2.rs:6259
SUMMARY: AddressSanitizer: 30 byte(s) leaked in 1 allocation(s).

[robobun]

Status: reproduced and fixed in this PR.

• Reproduced on main at f0f6b2c by running each listed bake file with a debug ASAN build under the runner's leak-check environment (BUN_DESTRUCT_VM_ON_EXIT=1, ASAN_OPTIONS with detect_leaks=1, LSAN_OPTIONS with test/leaksan.supp): 8 of the 10 listed files are clean in 4 of 4 runs, bundle.test.ts and css.test.ts each fail on the one known leak named in the new comment (bundler: free the ServerComponentParseTask after it generates its file #38004 and watcher: free the owned path of evicted watchlist entries #39197), and 3 entries named files that do not exist.
• This PR removes the clean files and the dead entries and documents the two that remain; the table in the description has the per-file results.

[coderabbitai]

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• test/no-validate-leaksan.txt

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Walkthrough

The LSAN exemption file removes the bun-repl test entry and replaces a broad dev-server leak note with targeted entries for the bundle and CSS tests.

Changes

LSAN exemption maintenance

Layer / File(s)	Summary
Update LSAN leak records test/no-validate-leaksan.txt	Removes test/cli/install/bun-repl.test.ts and documents leak locations for test/bake/dev/bundle.test.ts and test/bake/dev/css.test.ts.

Possibly related PRs

• oven-sh/bun#39197: Updates the same LSAN exemption file with different leak suppression changes.

Suggested reviewers: jarred-sumner, cirospaciari, dylan-conway

Merge Risk: ⚪ Minimal · up to 623ab

This localized test-coverage change re-enables leak checks for files verified clean while retaining exclusions for two files with known leaks. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes re-enabling LeakSanitizer checks for bake development tests that no longer leak.
Description check	✅ Passed	The description explains the problem, changes, retained exclusions, known leaks, and detailed verification results.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[claude]

LGTM — tightens the LSan suppression list, which is self-verifying via this PR's own ASAN lane.

What was reviewed:

• Confirmed the three removed dead entries (dev/deinitialization.test.ts, dev/react-cookies.test.ts, cli/install/bun-repl.test.ts) do not exist on disk and the eight re-enabled files do.
• Checked scripts/runner.node.mjs — the list is consumed by exact path match, so removals only add coverage; nothing is loosened.
• The two kept entries and their new comment match the leak reports and fix PRs cited in the description.

Extended reasoning...

Overview

This PR edits a single test-infrastructure file, test/no-validate-leaksan.txt, which is an opt-out list read by scripts/runner.node.mjs to decide which test files skip the exit-time LeakSanitizer check on the ASAN CI lane. It removes eight bake dev-server test files that no longer leak, removes three entries that name nonexistent files (dead no-ops), and replaces two vague block comments with a precise per-entry comment naming the remaining leak, its allocation site, and the PR that fixes it.

Security risks

None. This is a plaintext suppression list consumed only by the CI test runner; no runtime code, auth, or user-facing surface is touched.

Level of scrutiny

Low. The change only removes suppressions, which strictly tightens CI — if any of the eight re-enabled files still leaks, this PR's own ASAN run fails and blocks merge, so the change is self-verifying. The three dead entries were verified against the filesystem (all three paths are indeed missing; the corrected paths test/bake/deinitialization.test.ts and test/bake/dev/request-cookies.test.ts exist and were already running under the check). No entries are added other than the two that were already present (bundle.test.ts, css.test.ts), so nothing new is being exempted from checking.

Other factors

The PR description is unusually thorough: 4× runs per re-enabled file under the exact runner environment, a positive control (the two kept files still report leaks under the same harness, proving the check actually ran), and cross-references to the in-flight fix PRs (#38004, #39197). The runner reads this file line-by-line with comment/blank filtering and matches by exact relative path, so the edit cannot have unintended side effects on other entries. The one operational risk — that re-enabling LSan on eight subprocess-heavy bake files slows the ASAN lane — is acknowledged with timing data and is a CI-tuning concern, not a correctness one.

[robobun]

^{Updated 9:49 PM PT - Aug 15th, 2026}

✅ @robobun, your commit 623abc24599a951781e737c26f725c2b9cce1b1c passed in Build #99106! 🎉

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bunx bun-pr 39293

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bun-39293 --bun