[cramforce]

Summary

util.promisify(fn) needs the callback's shape to build a typed wrapper. When fn is typed any (a method of an untyped client, often obj.close.bind(obj)), there is no shape, and the call was refused.

An untyped argument now goes to a runtime wrapper, scr_util_promisify. It lives in its own runtime unit, scr_util_promisify.c, linked by a new utilPromisify feature together with the dyn-async and dyn-invoke units, so programs that don't promisify an untyped function are unchanged. The wrapper is an untyped function. Each call creates a promise, passes the call's receiver and arguments plus an error-first callback to fn, and settles once:

• a truthy error rejects;
• otherwise the first value after the error fulfills;
• a synchronous throw rejects;
• later callback calls are ignored.

This matches Node for plain functions. Node's promisify also copies the original's own property descriptors and prototype onto the wrapper and consults util.promisify.custom; the wrapper copies name and length, and an original with any other own property (util.promisify.custom among them) refuses with SC2020 where util.promisify runs, rather than returning a wrapper without them. The DEP0174 warning for an original that returns a promise is not reported. Both limits are on the limitations page. Typed functions keep the existing static wrapper, and their programs are unchanged.

Evidence

• 6452-promisify-untyped-functions.ts: untyped methods promisified bound and unbound, an extra callback value dropped, error rejection, a callback called twice, a synchronous throw, and the call's receiver reaching the function. Node and native agree in both lanes.
• The existing promisify and callbackify corpus programs pass in both lanes.
• npm.test.ts: node24-util-adapters now runs its invalid-argument promisify scenarios as Node does and stops at an unrelated deferred Object.create refusal; its known state records that instead of the earlier promisify refusal.
• Zero-cost gate against Compile process.send presence, process.exitCode reads, wider stream hooks, void race entries and promisify of callbacks #1429 (opt/bc-node-surface at 25e40af, which merges main 9d80738): PASS, 3293 programs identical (bench, self-hosted compiler, corpus) and 2 that fail on both sides; bench geomean −0.25% [−0.61%, +0.25%], self +1.16%, both within tolerance.
• self-hosting-runtime-features.test.ts covers the new feature's detection, and the runtime-pack and executable-cache unit tests pass.
• Lint, format, test:ts7 --baselines-only, the diagnostics suite and the self-hosting IR build are clean. contract-acyclic.ts fails in the diagnostics suite the same way on main.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated
scriptc	Ready	Preview, v0	Oct 21, 2026 2:53am UTC