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test262 regression on main — parity 96.5%→95.8%, 322 tests (bisecting) #6013
Description
test262 regression on main — parity 96.5% → 95.8%, 322 tests newly failing
A full test262 sweep of main at the #6008 tip (76cc2b996) regressed vs the #5979 tip (28948ea44):
| metric | #5979 (good) | #6008 (bad) |
|---|---|---|
| parity | 96.5% | 95.8% |
| Temporal self-validated | 99.1% | 96.7% |
| pass | 35242 | 34981 |
| runtime-fail | 1164 | 1421 |
322 tests newly failing, 61 newly fixed (net −261). Harness-confirmed (not a measurement artifact): e.g. built-ins/Boolean/prototype/toString dropped 100% → 67%.
Newly-failing by area
- built-ins/Temporal 159
- language/expressions 119
- language/arguments-object 15, built-ins/Proxy 5, Boolean 3, Number 3, Function 2, TypedArray 2, others 14
Reason clusters
TypeError: method is not a function— 131(no output)(crash/SIGSEGV) — 126Expected SameValue(x, y)— 35Cannot read properties of undefined— 10
Regression window
28948ea44 (good) .. 76cc2b996 (bad) — 21 commits. Broad-impact suspects: #6004 (native_call_method.rs method-dispatcher change), #5978/#5981 (GC), #5988 (async-step deadlock class). Bisect in progress.
Sample newly-failing cases
built-ins/Boolean/prototype/toString/S15.6.4.2_A2_T1.js
built-ins/Number/prototype/toString/S15.7.4.2_A4_T01.js
built-ins/Function/prototype/S15.3.5.2_A1_T2.js
built-ins/Temporal/Duration/compare/order-of-operations.js
built-ins/Temporal/Duration/from/order-of-operations.js
built-ins/Proxy/getOwnPropertyDescriptor/trap-is-undefined-target-is-proxy.js
annexB/language/global-code/block-decl-global-block-scoping.js
Measured on an internal Linux sweep host (built-ins + language + intl402 + annexB, jobs 6). A bisect+fix is underway; this issue tracks the root-cause + fix/revert PR.
Activity
proggeramlug commentedon Jul 5, 2026
Bisected. Culprit = #5874 "Improve Zod compatibility support" (
849f297a8).git bisect(good28948ea44.. bad76cc2b996), witness slice = built-ins/Boolean/prototype/toString + Number/prototype/toString + Temporal/Duration/{compare,from}:4f5bc6adb(#5981)849f297a8(#5874) — first bad76cc2b996(main tip)(
532853f4abetween them is a metadata-only chore.)#5874 is a 156-file monolithic squash that swept in unreviewed codegen/runtime WIP + two 5.1 MB binaries (
constv,direct) + ~30 straytests/*.shalongside the intended Zod work. Two swept changes dominate:codegen/lower_call/property_get/number_string.rsgated the universal.toString()interception onis_numeric_expr || is_bigint_expr, so boxed built-in receivers (new String()/new Number()/new Date()) with a user-assigned built-in method bypassed the brand-check and stopped throwingTypeError→ the "method is not a function" / SameValue clusters. (property_get.rsreclassifiedtrim/case-conversion the same way.)Object.getPrototypeOf(result) === construct.prototype) → the Temporal 159 +(no output)crash clusters.Fix = #6015 (inverse-patch of the #5874 payload rebased onto current main; #5991 preserved; #5983 stdlib change untouched). Witness slice returns to 98.3% / self-validated 100% / Temporal.Duration 100%. Supersedes the stale #5994.
proggeramlug commentedon Jul 5, 2026
Resolved by #6015 — regression fully healed
A full re-sweep of
mainat the #6015 tip confirms the 322-test regression is reverted with the grind wins preserved:Culprit was #5874's contaminated squash (unreviewed codegen/runtime WIP swept in alongside the Zod work); #6015 inverse-patched it out while preserving the legitimate later commits (#5991/#5999/#5983). Temporal self-validation and the Boolean/Number/Function brand-check negatives are all restored; net parity is now slightly above the pre-regression baseline. Closing.