mirror of
https://github.com/danbulant/oxc
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a4ae4505f1
Compress `[].concat(a).concat(b)` into `[].concat(a, b)`. **References** - [Spec of `Array::concat`](https://tc39.es/ecma262/multipage/indexed-collections.html#sec-array.prototype.concat) --- ### The new assumption I added a new assumption description in `crates/oxc_minifier/README.md`: "Errors thrown when creating a String or an Array that exceeds the maximum length can disappear or moved". This is an assumption held by other minifiers. Without this assumption, we have to treat `+` and array creation/update to have a sideeffect and that limits the minification. For input: ```js [...Array(Number(2n ** 32n - 1n)),""] " ".repeat(Number(2n ** 29n - 24n - 1n)) + ' ' export {} ``` (Note that `2 ** 32 - 1` is the max array length and `2 ** 29 - 24` is the max string length on V8.) This code errors with too long array and too long string on V8 based runtimes. terser outputs: ```js Array(Number(2n**32n-1n))," ".repeat(Number(536870887n));export{}; ``` No error will happen with this code. SWC outputs: ```js [...Array(Number(2n**32n-1n))]," ".repeat(Number(2n**29n-24n-1n));export{}; ``` No error will happen with this code. [playground](https://play.swc.rs/?version=1.10.7&code=H4sIAAAAAAAAA4vW09NzLCpKrNTwK81NSi3SMMpT0NJSMAZSugqGeZqaOkpKsbxcSgpKekWpBamJJajqjCxB6oxMYKoVtBXUFdR5uVIrCvKLShSqa3m5AGRqy%2FBiAAAA&config=H4sIAAAAAAAAA32UO3LjMAyG%2B5zCozrFjostcoDtcgYOTYIyvXxoCNCxJuO7L0RJtjeG3En48AMkAOL7bbfrTmi6j903f%2FLPoAtCuf2zBcdE%2BsKWDkzUaIofqHtf6Qkn5HRAaKbrTDrSpQdqKtz%2F2u8XRRdyRlgViy365N34mNPkOBRAfLCxlUPWCInwf%2F3CSv6aAJX6aD%2FkHECnF0RpVD4R9FCkwCaHoAcEddZFiDKdVBePWUoxwUpg1VDyIPJkPfmcOOcztaCtMtmCgHwBQ%2F4MkoxzsSwhX0%2B4T8MWDrXvW59%2FqOGsQ9Uk5IRLawmfVoh6zB5JuZqkEs5wowYzXIr7U%2BmdKkC1pGfdKfu00ZO%2FAFyBoBGTjiDFbR6O52lL7V4qfXI8sjQKnOdbumWCnouqvHdCZafKQCEvdbOArQamyhrpOAveKB96Cwqc41kRQuOXJ3OUktI4QHYC4P5qJ03VDNTtFW7w6UG8wH%2F4liQP2OIRNR23KY7xkMOLBBHomO0LB24F5W1ceEtchm1ekwUeDbCiS8UGnpcAPwDKKrR9%2BTQb%2FDw4oupDPtzXxOJwve3hqFN%2Ff%2B%2FzKn5bHLqYbW1wWfJTf%2BfV%2FLu7O61beD1B5%2FFzFbac13%2FKOhgeLwYAAA%3D%3D) esbuild outputs: ```js [...Array(Number(2n**32n-1n))]," ".repeat(Number(2n**29n-24n-1n))+"";export{}; ``` No error will happen with this code. [esbuild try](https://esbuild.github.io/try/#dAAwLjI0LjIALS1taW5pZnkAWy4uLkFycmF5KE51bWJlcigybiAqKiAzMm4gLSAxbikpLCIiXQoiICIucmVwZWF0KE51bWJlcigybiAqKiAyOW4gLSAyNG4gLSAxbikpICsgJyAnCmV4cG9ydCB7fQ) OXC outputs: ```js [...Array(Number(2n**32n-1n))]," ".repeat(Number(2n**29n-24n-1n))+" ";export{}; ``` The array error won't happen and the String error will happen with this code. [playground](https://playground.oxc.rs/#eNpVT71OwzAQfhXrlv4QIhpgIBtLR8SOGZxwCUH22To7baMo746dNEVMd5/u+7sRaijhI8/zV2Y1bN96UyFvCxL7vXiM414caLfLJEj4lCRBSMgZHarwn1u8JG7xtCrEndiIjSS8OMtBjJMkyMBCOQL3lIYfKKgLlIF7zEB3FKBslPYR+No6XC9+MJXVKwqsyDeWzZU8ZeAUe+TZ0vZc47HTSMpEAwjoQ/7jY7JjjKQTvitG8n/ilDuL437zXtyC4hZjKUBfPByeITJq+4UtpvoRmI66plu4tTUpIRovNc/fXcx2qr69YRS1+opmJwps9VHbc9KfkCvr43npNU2/v/WIsw==) |
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| .. | ||
| oxc | ||
| oxc_allocator | ||
| oxc_ast | ||
| oxc_ast_macros | ||
| oxc_cfg | ||
| oxc_codegen | ||
| oxc_data_structures | ||
| oxc_diagnostics | ||
| oxc_ecmascript | ||
| oxc_estree | ||
| oxc_isolated_declarations | ||
| oxc_language_server | ||
| oxc_linter | ||
| oxc_macros | ||
| oxc_mangler | ||
| oxc_minifier | ||
| oxc_napi | ||
| oxc_parser | ||
| oxc_prettier | ||
| oxc_regular_expression | ||
| oxc_semantic | ||
| oxc_span | ||
| oxc_syntax | ||
| oxc_transformer | ||
| oxc_traverse | ||
| oxc_wasm | ||