fix(javascript): emit no fork when a literal stdio array omits the IPC channel (#7992)

* fix(javascript): emit no fork when a literal stdio array omits the IPC channel

Node's fork() requires an explicit stdio array to carry the IPC channel:

    if (!ArrayPrototypeIncludes(options.stdio, 'ipc'))
      throw new ERR_CHILD_PROCESS_IPC_REQUIRED('options.stdio')

The throw is synchronous, before any child process exists, but the analysis
reported a resolved fork with stdioMode "array" — byte-identical to the valid
`[..., "ipc"]` form — which projects to a child-process node, a resolved spawns
relation and resolved connects-stdio.

Measured on Node 24.22.1:

    fork({stdio: ["inherit","inherit","inherit"]}) -> THROWS ERR_CHILD_PROCESS_IPC_REQUIRED
    fork({stdio: ["pipe","pipe","pipe"]})          -> THROWS ERR_CHILD_PROCESS_IPC_REQUIRED
    fork({stdio: ["ipc"]})                         -> SPAWNED connected=true
    fork({stdio: ["inherit","inherit","inherit","ipc"]}) -> SPAWNED connected=true
    fork({stdio: "pipe"})                          -> SPAWNED connected=true
    spawn({stdio: ["inherit","inherit","inherit"]})-> SPAWNED connected=false

A string stdio is normalised with "ipc" appended, so only the array form can omit
it. The same array is valid for spawn, which has no IPC requirement.

Drop a fork candidate only when its stdio array is fully literal and provably
lacks "ipc"; a spread or a non-literal element may still supply the channel and
stays a candidate.

* chore: retrigger title and readiness checks after the title was corrected
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吴佳浩Alben authored and GitHub committed 2026-10-29 13:38:29 +08:00
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import { expect, it } from "vitest";
import { analyzeJavaScriptSemantics } from "./javascriptSemanticAnalysis.js";
/**
* Node's `fork()` requires an explicit `stdio` array to carry the IPC channel:
* `if (!ArrayIncludes(options.stdio, 'ipc')) throw new ERR_CHILD_PROCESS_IPC_REQUIRED`.
* The throw is synchronous, before any child process exists, so such a call is
* not a spawn. A string `stdio` is normalised with `"ipc"` appended, so only the
* array form can omit it, and the same array is valid for `spawn`.
*/
const spawnsFor = (call: string) =>
analyzeJavaScriptSemantics(
`import { fork } from "node:child_process"; ${call};`,
).childProcessSpawns;
it.each([
["three inherits", `["inherit", "inherit", "inherit"]`],
["three pipes", `["pipe", "pipe", "pipe"]`],
["ignore then pipes", `["ignore", "pipe", "pipe"]`],
["one inherit", `["inherit"]`],
["an empty array", `[]`],
] as const)(
"emits no fork for a literal stdio array with %s and no ipc",
(_name, stdio) => {
expect(spawnsFor(`fork("worker.js", { stdio: ${stdio} })`)).toEqual([]);
},
);
it.each([
["a fourth element", `["inherit", "inherit", "inherit", "ipc"]`],
["only ipc", `["ipc"]`],
["ipc and a pipe", `["pipe", "ipc"]`],
] as const)("keeps the fork for a stdio array with %s", (_name, stdio) => {
expect(spawnsFor(`fork("worker.js", { stdio: ${stdio} })`)).toEqual([
expect.objectContaining({ method: "fork", stdioMode: "array" }),
]);
});
it.each([
["a string stdio", `fork("worker.js", { stdio: "pipe" })`],
["omitted stdio", `fork("worker.js", {})`],
] as const)("keeps the fork for %s", (_name, call) => {
expect(spawnsFor(call)).toHaveLength(1);
});
it.each([
["a spread element", `[...base, "ipc"]`],
["a non-literal element", `[channel]`],
] as const)(
"keeps the fork when %s may still supply the channel",
(_name, stdio) => {
expect(spawnsFor(`fork("worker.js", { stdio: ${stdio} })`)).toHaveLength(1);
},
);
it("keeps the same array for spawn, which has no IPC requirement", () => {
const spawned = analyzeJavaScriptSemantics(
`import { spawn } from "node:child_process"; spawn("tool", [], { stdio: ["inherit", "inherit", "inherit"] });`,
);
expect(spawned.childProcessSpawns).toHaveLength(1);
});