node:domain: EventEmitter domain error routing segfaults

[andrewtdiz]

Summary

Current node-suite/domain/members-emitter-errors segfaults in Perry when a domain-owned EventEmitter emits error. Node routes the emitter error through the domain error handler and returns false from emit().

Repro

import domain from "node:domain";
import { EventEmitter } from "node:events";

const d = domain.create();
const ee = new EventEmitter();

d.on("error", (err: any) => {
  console.log("domain error:", err.message, err.domain === d, err.domainThrown, typeof err.domainBound, err.domainEmitter === ee);
});

d.add(ee);
console.log("members after add:", d.members.includes(ee), ee.domain === d, d.members.length);
console.log("emit returned:", ee.emit("error", new Error("emitter boom")));
d.remove(ee);
console.log("members after remove:", d.members.includes(ee), ee.domain, d.members.length);

Current behavior

Node v26.3.0:

members after add: true true 1
domain error: emitter boom true false undefined true
emit returned: false
members after remove: false null 0

Perry on current-main scan baseline 460fc3d6a:

Segmentation fault (core dumped)
exit=139

Focused parity output:

node-suite/domain/members-emitter-errors (output mismatch)
Perry: Segmentation fault (core dumped)

Suggested scope

Fix only node:domain membership and EventEmitter error routing for domain-owned emitters: domain.add(emitter), emitter.domain, domain error metadata (domain, domainEmitter, domainThrown, domainBound), emit("error", err) return value, and domain.remove(emitter).

Non-goals: broader domain async context semantics, unrelated EventEmitter behavior, and process-level uncaught exception handling beyond this fixture.

[andrewtdiz]

I am taking this as a focused node:domain EventEmitter membership/error-routing slice.

Planned scope: make domain.add(emitter) route emitter.emit("error", err) through the domain error listener with Node-shaped metadata (err.domain, err.domainEmitter, domainThrown, domainBound), return false after the domain handles it, and make domain.remove(emitter) clear membership.

Non-goals: broader domain async context propagation, process-level uncaught exception semantics beyond this fixture, and unrelated EventEmitter behavior.

[andrewtdiz]

Reproduction refinement before editing: the segfault happens before domain error routing. On latest origin/main (2803f7dae), a minimal new EventEmitter() program crashes under the same no-auto linked path, and node-suite/events/imports/default-import / named-imports fail the same way.

I am keeping this issue as the claimed tracker because node-suite/domain/members-emitter-errors is the fixture that surfaced it, but the implementation root is now narrower: restore the node:events EventEmitter constructor/handle surface so events imports and the domain member fixture can run. If domain routing still diverges after that constructor crash is fixed, I will keep the remaining changes scoped to the same fixture-backed domain behavior.

[andrewtdiz]

Opened draft PR: #4398

Validated the focused domain/EventEmitter route against Node v26 and Perry:

• Node oracle: npm exec --yes --package=node@26 -- node --experimental-strip-types test-parity/node-suite/domain/members-emitter-errors.ts
• Focused parity: PERRY_NO_CACHE=1 CARGO_BUILD_JOBS=1 RUSTC_WRAPPER= CARGO_TARGET_DIR=/root/perry-worktrees/.build-targets/http2-refused npm exec --yes --package=node@26 -- ./run_parity_tests.sh --suite node-suite --module domain --filter members-emitter-errors (PASS 1, report test-parity/reports/parity_report_20260604_130428.json)
• Full domain parity: PASS 3, report test-parity/reports/parity_report_20260604_124326.json
• Rust checks: cargo check --release -p perry-ext-events, cargo check --release -p perry-stdlib, cargo build --release -p perry -p perry-runtime -p perry-stdlib, cargo test --release -p perry-ext-events --lib
• Hygiene: rustfmt --check, ./scripts/check_file_size.sh, git diff --check

[andrewtdiz]

Opened PR: #4398

Validation from the final pass:

• cargo check -p perry-ext-events
• cargo test -p perry strip_dedup -- --nocapture
• cargo check -p perry
• cargo build -p perry --release
• cargo build -p perry-ext-events --release
• PERRY_NO_AUTO_OPTIMIZE=1 PERRY_NO_CACHE=1 PERRY_ALLOW_UNIMPLEMENTED=1 target/release/perry test-parity/node-suite/events/imports/named-imports.ts -o /tmp/perry_events_named_imports && /tmp/perry_events_named_imports
• Node 26 parity: events --filter imports PASS 3/3 (parity_report_20260604_132124.json)
• Node 26 parity: domain --filter members-emitter-errors PASS 1/1 (parity_report_20260604_132243.json)

I also reran the broader events --filter emitter; it still has unrelated gaps in capture-rejections, emit-multiple-args, event-names-symbols, and instanceof, but the focused domain regression and events import fixtures pass.

[andrewtdiz]

Opened draft PR: #4402

The issue fixture now compiles and runs with the expected output:

members after add: true true 1
domain error: emitter boom true false undefined true
emit returned: false
members after remove: false null 0

Also checked the events default/named/namespace import fixtures and focused runtime GC native-handle tests.