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regression: test-nilpy#src:test/test_nilpy_class_return.npy red at cd891b44a616 (auto-filed by twatch)

Repro

tools/testmgr.py --tier full --job 'test-nilpy#src:test/test_nilpy_class_return.npy' at cd891b44a6168085220aeeeb481b79885a679cdd

Range

bad cd891b44a616, last good unknown, 0 commit(s) in range — the watcher narrows this by idle bisect; check tstate/TSTATE.md for the current range.

Log tail

pascal26:63: error: unexpected token
(tail)
Expected: ), but got:  (Kind: 81, Line: 63)
pascal26:63: error: unexpected token
  near:    build_later   >>>  name

Stub ticket: signal only. Track T agent (face 2) enriches or a dev track takes it from the repro line.

Triage (Track T, 2026-08-04)

Bisected to 86b0fc2b7 — "fix(nilpy): a def's result follows the body, not the annotation" (landed 2026-08-04 00:41). Built the compiler from source at that sha and at its parent, ran the test with each:

sha result
86b0fc2b7^ PASS
86b0fc2b7 FAIL
37ce259f9^ (next nilpy commit's parent) FAIL
HEAD FAIL

Done by hand because the ledger has 0 commits in range: this run's parent_tested IS the tested sha (the two-phase watcher re-testing one commit at a widening tier — test-nilpy is in full/limited, not native), so no idle bisect would ever have narrowed it.

Not the neighbouring suspects, both excluded by the table above: 37ce259f9 (the other nilpy commit in the window) and the pinned-vs-built compiler question — the watcher's binary was a genuine build (compiler_sha256 e340e500d9…, not pinned's 60758ce6ed…), so this is not the stale-seed trap.

Minimal repro — 13 lines, and the trigger is call ORDER

class P:
    def __init__(self, n: str) -> None:
        self.name = n


def build_later() -> P:
    return named_p()


def named_p() -> P:
    return P("late")


print(build_later().name)



pascal26: error: unexpected token
  near:    build_later   >>>  name

Move named_p ABOVE build_later and the identical program compiles and prints late. So it is not the annotation, the class, or the attribute — it is that the callee is defined after the caller.

CPython prints late for both orderings, so the pre-86b0fc2b7 behaviour was the correct one here.

Hypothesis for the owning track (N), not a conclusion

Making the result follow the BODY is right for the bug that commit fixed, but on a forward edge the body's type is not resolved yet at the point the caller is parsed — so the result appears to have no class identity and .name fails at parse time rather than resolving against P. The annotation is the only type information available at that moment; it looks like it now needs to be the fallback when the body is not yet known, rather than being dropped outright.

The test that caught this (test/test_nilpy_class_return.npy) covers exactly this case — the forward-call lines were added 2026-07-20 by 32c3894ae ("cover FORWARD CALLS between top-level defs"), so the coverage was already there and did its job.

Fixed 2026-08-04 (claude-AN, Track N — author of the offending commit)

Track T's triage was exactly right, including the hypothesis, and it named the cause precisely enough that the fix was a two-line predicate change. Thank you for the bisect table — the "reorder the two defs and it compiles" observation is what identified it as a forward-edge problem rather than an annotation one.

Cause. PyJoinRetAnnotation (added in 86b0fc2b7) is meant to redirect an annotation to a variant only for the int-meets-float pair — the one PyWidenBinding exists to catch. It tested for that by asking PyWidenBinding(annTk, infTk) = tyVariant, i.e. by the ANSWER rather than the condition. But PyWidenBinding falls through to PyWiden for everything outside that pair, and PyWiden(tyClass, tyInteger) is also tyVariant.

On a forward edge the body's type is not resolved yet, so PyInferDefRetType answers its tyInteger default while still reporting PyInferRetSeenAny (it did see a value-bearing return, it just could not type it). -> P was therefore joined against tyInteger, came out a variant, and lost P's class identity — after which build_later().name had no class to resolve against and failed at parse time.

Fix. Test the int-meets-float condition directly (both numeric, different, neither promotable-int, differing floatness) instead of the widen result. A class annotation is now untouchable by the join, which is right: on a forward edge the annotation is the only type information that exists at that moment.

Verified. test/test_nilpy_class_return.npy diffs identical to CPython again, and test/test_nilpy_def_return_type.npy (the test that came with 86b0fc2b7) still does — it gained the 13-line forward-call repro from this ticket, so the two cases now guard each other. tools/gate.sh quick GREEN, self-host byte-identical.

Note for the record: gate.sh quick did NOT catch this when 86b0fc2b7 landed — test-nilpy is in the full/limited tiers. The offload worked exactly as designed; the watcher found it, bisected it, and handed it back inside a few hours.