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conformance: test_gap_6301_event_target_subclass regressed on main (untriaged, inside required conformance-smoke-complete) — fixed 07-13, red again by 07-31 #7178
Description
test_gap_6301_event_target_subclass is failing on main (pass -> parity_fail per the harness log) and is not in test-parity/known_failures.json — an untriaged regression of a test that was fixed on 2026-07-13 by 81ab8e5d6 (issue #6301, native-base EventTarget subclassing).
Why it matters more than a normal red
It fails inside conformance-smoke (4), which feeds conformance-smoke-complete — a required status check. An untriaged regression in a required context blocks every PR (or trains people to admin-bypass, which is worse).
Independent confirmations
- The fix(gc): re-derive a string-literal operand below the collection point (#7114) #7116 session's gap run hit it at 166/438 and verified the failure is byte-identical on pristine base (
ff85fd483) — i.e. it pre-dates all of the 2026-07-31/08-01 merges. - The fix(runtime): make WebAssembly.Module instanceof recognize constructed modules #7124/test(compile): lock in auto-opt freshness on runtime/stdlib source edits #7155 triage reproduced it on both PRs'
conformance-smoke (4)runs (disjoint diffs — inherited by construction).
What's needed
- Bisect between
81ab8e5d6(fix landed, green) andff85fd483(confirmed red) — the window is ~2.5 weeks of merges. - Native-base subclassing is a documented weak family (5 defects, keyed on literal
extendsnames) — the regression likely rode in on one of the globalThis/proto/builtin-install changes in that window. - Until fixed: either triage into
known_failures.jsonwith provenance (issue # + date, per the test-parity: audit known_failures.json — every entry needs an issue # and date #797 skip-list policy) to unblock the required context honestly, or fix it. Leaving it untriaged-and-red in a required context is the worst of both.
Activity
proggeramlug commentedon Aug 7, 2026
Already fixed — no further code change needed
This is the same regression as #7518 (same failing gap test, same
class Bus extends EventTargetshape). It was fixed and closed by #7520 on 2026-08-06 (6a051ec18), five days after this issue was opened. #7520 closed #7518 but never closed this one.Root cause (from #7520 / #7518)
c6ed8175d(#6853, 2026-07-30) added"EventTarget"tobuiltin_constructor_spec_lengthsoEventTarget.length === 0like Node. That flipped an incidental gate intry_dispatch_value_called_proto_method: constructors that share the globalThis no-op thunk were only excluded because they had no recorded.length. With a length recorded,js_fetch_or_value_super(<EventTarget>, this, …)re-dispatched asbus.EventTarget()and threwTypeError: EventTarget is not a function.Fix on main
#7520 makes the exclusion explicit and table-driven via
is_global_this_builtin_constructor_name/GLOBAL_THIS_BUILTIN_CONSTRUCTORS, and adds a per-PR unit test (global_builtin_constructor_values_are_not_redispatched_by_name) so a future.lengthaddition cannot re-open the hole.Re-verified on current
origin/main(6fb58cdea)test_gap_6301_event_target_subclassis byte-identical tonode --experimental-strip-types(Node 26.5.1), exit 0 on both sides.global_builtin_constructor_values_are_not_redispatched_by_namepasses.test-parity/known_failures.json.Closing as completed. No PR required.