René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ffi: Fast FFI buffer/arraybuffer signatures reject bigint after optimization","articleBody":"### Version\n\nmain\n\n### Platform\n\n```text\nmacOS 26.5.2\n```\n\n### Subsystem\n\nffi\n\n### What steps will reproduce the bug?\n\n`repro.c`\n```c\n#include \u003cstdint.h>\n\n__attribute__((visibility(\"default\")))\nuintptr_t pointer_to_usize(void* pointer) {\n  return (uintptr_t)pointer;\n}\n```\n\nBuild it by running\n```sh\n$ cc -dynamiclib repro.c -o librepro.dylib\n```\n\n`repro.js`\n```js\nimport { dlopen } from \"node:ffi\";\n\nconst { lib, functions } = dlopen(\"./librepro.dylib\", {\n  pointer_to_usize: {\n    arguments: [\"buffer\"], // Also reproduces with 'arraybuffer'.\n    return: \"u64\",\n  },\n});\n\nfunction call(value) {\n  return functions.pointer_to_usize(value);\n}\n\nconsole.log(\"before:\", call(0n));\n\ntry {\n  for (let i = 0; i \u003c 1_000_000; i++)\n    call(0n);\n  console.log('after:', call(0n));\n} catch (error) {\n  console.log('after:', error.code, error.message);\n}\n\nlib.close();\n```\n\nRun it using\n```sh\n$ node --no-warnings --experimental-ffi --allow-natives-syntax repro.js\n```\n\n### How often does it reproduce? Is there a required condition?\n\nAlways\n\n### What is the expected behavior? Why is that the expected behavior?\n\n```console\nbefore: 0n\nafter: 0n\n```\n\nOptimization should not change accepted inputs; `buffer` and `arraybuffer` signatures should continue accepting documented pointer-like values such as `bigint`.\n\n### What do you see instead?\n\n```console\nbefore: 0n\nafter: ERR_INVALID_ARG_VALUE Argument 0 must be a buffer or an ArrayBuffer\n```\n\nThe initial generic call accepts `0n`, but after optimization the same call throws `ERR_INVALID_ARG_VALUE`\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/trivikr","@type":"Person","name":"trivikr"},"datePublished":"2026-07-21T03:41:41Z","url":"https://github.com/nodejs/node/issues/64638"}