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Compiled async delegation loses rejection identity for nested iterator-result helper #3668
Description
A valid iterator-result object produced by a nested helper during async-generator delegation causes the compiled engine to lose the original rejected value. Both Node v22.23.2 and the interpreted engine print true 0; a saved standalone compiled assembly prints false 0.
async function check(request, final, getter) {
const marker = {};
let first = true, returns = 0;
function step() {
return {
get done() { if (getter === "done") throw marker; return final; },
get value() { if (getter === "value") throw marker; return Promise.reject(marker); }
};
}
const iterator = {
next() {
if (request !== "next" && first) { first = false; return { value: 1, done: false }; }
return step();
},
throw() { return step(); },
return() { console.log("return", ++returns, arguments.length); return step(); }
};
async function* run() { yield* { [Symbol.iterator]() { return iterator; } }; }
const generator = run();
if (request !== "next") await generator.next();
try {
if (request === "return") await generator.return(9);
else if (request === "throw") await generator.throw("injected");
else await generator.next();
} catch (error) { console.log(error === marker, returns); }
}
async function main() { await check("next", true, "none"); }
main();Verified with compiler source unchanged from PR #3663 baseline a1b016466 (verification binary includes the interpreter-only correction 774f626b4):
dotnet SharpTS.dll --compile source.ts --standalone --verify -o repro.dll
Compiled to repro.dll
IL verification passed.
dotnet repro.dll
false 0
Moving step, its captured configuration, and the iterator to top-level storage makes the corresponding eight exclusion controls pass in both engines. This report preserves the original failing shape; the exact compiler cause has not been established. The result is a valid object, unlike the deliberately invalid result cases in #3661. done is true here, so no rejection cleanup is required, unlike #3666.
Discovered while verifying PR review comment 4546709732. This unchanged compiled path was kept separate from the scoped interpreter fix. Artifact fixtures are retained at artifacts/rejection-close/exclusion-0.ts in the isolated review worktree.
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