Malte Ubl eb7a99172f Test class downcasts inline and borrow the checked operand
`x as Sub` lowered to a call to an interned %class.assert helper that
unwrapped a union box, retained the payload twice, compared the class-id
range, and threw on mismatch; every use paid a call, three retains, two
releases and a pending check (2,152 sites in tsc-ts). Plain operands
(locals and field reads, which isSafeToRepeat already admits) now lower
to the check itself: per compatible union arm a tag test plus, where the
arm is not already the target or a subclass, an instanceOf range test,
selecting the downcast payload, with the helper's exact TypeError as the
final arm. Other operands keep the helper so they are evaluated once.

The backend borrows through the result: instanceOf reads its operand as
a receiver instead of retaining a temporary, and downcast/upcast are
borrowable, edge-preserving projections, so `(node as Sub).field` and
method receivers on a cast no longer touch reference counts. The mismatch
arm unwinds directly (previous commit) and stays out of the hot path.

Corpus 4432 pins the Node-observable behavior of failing casts (a
TypeError before any later read, unwinding through finally blocks and
callbacks) and of successful casts from bases, subclasses and unions; a
harness test pins the exact messages, which Node cannot oracle.
2026-10-09 11:59:27 -05:00
2026-07-22 18:08:04 -05:00
2026-10-07 19:07:02 -05:00
2026-10-08 21:18:31 -05:00
2026-07-22 18:08:04 -05:00
2026-07-22 18:08:04 -05:00

scriptc

Vercel Labs Experiment npm version: scriptc License: Apache-2.0 npm downloads per month: scriptc

scriptc compiles TypeScript and JavaScript to native executables and WebAssembly. It uses TypeScript's type information to compile supported code to native instructions. Static builds run without Node.js or a JavaScript engine.

For npm dependencies and any-typed code, enable --dynamic to include the embedded quickjs-ng engine. Dependency JavaScript is included at build time.

scriptc is experimental and supports a subset of JavaScript, TypeScript, and Node.js APIs. See the limitations and Node.js compatibility reference before using it for an existing project.

Installation

Install with Node.js 24 or later and npm:

$ npm install -g scriptc

The installed compiler runs natively on supported macOS, Linux, and Windows hosts. Native compilation and execution do not require Node.js. Standalone compiler archives are also available from GitHub Releases.

Executable builds require a platform linker and SDK/sysroot. See the quickstart for prerequisites and platform support for host requirements, cross-compilation, and WebAssembly.

Build a program

Create hello.ts:

const who = process.argv.length > 2 ? process.argv[2] : "world";
console.log(`hello, ${who}`);

Compile and run it in one step:

$ scriptc run hello.ts
hello, world

Or write a standalone executable:

$ scriptc build hello.ts -o hello
$ ./hello scriptc
hello, scriptc

These examples use POSIX shell syntax. On Windows, build hello.exe and run it with .\hello.exe.

Use scriptc coverage hello.ts to check which operations compile statically, require dynamic execution, or are unsupported. See coverage reports for details.

Use Node APIs

Supported Node APIs compile to the native runtime. For example, server.ts:

import { createServer } from "node:http";

const server = createServer((req, res) => {
  res.setHeader("content-type", "application/json");
  res.end(JSON.stringify({ path: req.url }));
});

server.listen(8080, () => {
  console.log("listening on http://localhost:8080");
});
$ scriptc build server.ts -o server
$ ./server
listening on http://localhost:8080

Use npm packages

Pass --dynamic to embed an npm package's JavaScript in the executable. The result does not read node_modules at runtime.

Create cli.ts:

import pc from "picocolors";

console.log(pc.green("hello from scriptc"));
$ npm install picocolors
$ scriptc build cli.ts --dynamic -o cli
$ ./cli
hello from scriptc

Enabling --dynamic does not add support for unsupported statically typed calls. See npm dependencies for package resolution and the boundary between static and dynamic code.

Documentation

Contributing

See CONTRIBUTING.md for source setup, testing, native artifact builds, and docs development.

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