mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-21 05:50:55 +08:00
Chris Tate
e81e4f5ab5
- ambientUndefVarRootOf walks calls, `new`, optional chains, assertions, instantiation expressions, and tagged templates, and accepts `declare function` and trap-binding roots: Node erases the declaration, so the root read IS the crash — lowerCall, member reads, assignments, and variable declarations lower the whole statement to the catchable ReferenceError, arguments never evaluate, and the never-initialized binding registers as a trap whose references can never run
- never-read unmappable bindings with value-only initializers and writes emit nothing: Node builds the value and drops it, so `var xs2: typeof Array;` and the write-only `var f2: { <T, U>(x: T, y: U): T }` compile instead of fencing on a type the program never consumes
- null!/as-any bindings whose types keep generic signatures (or intern empty record shapes) register no storage; generic-method calls and member reads through them compile to Node's exact TypeError, nullish-to-nullish flows to nothing, heritage-clause uses decline the family so mixin resolution keeps its fence, and checked-dynamic (`any`) bindings keep their dyn story untouched
- assertion-shaped generic arrows (`< <T>(x: T) => T >((x) => x)`) register like annotated bindings and monomorphize per call; stdlib generic members (Promise.then, Object.defineProperty) take the SC2020 lib fence, and Function.prototype.apply/call/bind on compiled function values name the direct-call spelling
- diagnostics fixtures that used `declare` to conjure unconstructible values now conjure them by cast so each fence family keeps its pin; snapshots re-recorded, the deferred checker-panic diagnostic now flushes at its first reference as designed
83 lines
3.7 KiB
TypeScript
83 lines
3.7 KiB
TypeScript
// The lib-fence battery: everything here TYPECHECKS against the real
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// standard library (es2023) — the old minimal-ambient world rejected most
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// of it with "Cannot find name" — and every statement must terminate in a
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// clean lowering diagnostic (SC2020 for surface with no lowering, a
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// specific fence otherwise). Never an ICE, never a silent mis-lowering.
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// Globals as values and calls. (Symbol(desc) itself LOWERS now — the
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// symbol battery lives in the corpus; what stays fenced is the well-known
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// surface below.)
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const iter = Symbol.iterator;
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const g = globalThis;
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const nan = NaN; // lowers now — a non-finite numeric literal like Infinity
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const s5 = String(5);
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const n5 = Number.NaN; // lowers now, with the other Number constants
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const isArr = Array.isArray([1]);
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const merged = Object.assign({}, { a: 1 }); // the empty-target literal-source shape lowers now (it IS the source literal)
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const aliasedAssign = Object.assign(merged, { b: 2 }); // aliased targets stay fenced (real mutation of a live object)
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const refl = Reflect.has({ a: 1 }, "a");
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const parsedMs = Date.parse("2024-01-01");
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const fmt = new Intl.NumberFormat();
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// Constructors.
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const d = new Date();
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const wm = new WeakMap();
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const px = new Proxy({ a: 1 }, {});
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const buf = new ArrayBuffer(8);
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const st = new Set(new Set([1, 2])); // array seeds lower; Set/iterable seeds stay fenced
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// (new Error / TypeError / RangeError / SyntaxError now LOWER — the error
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// battery lives in the corpus; what stays fenced is the rest of the family
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// and the unlowered members of lowered error objects.)
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const agg = new AggregateError([]);
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const stack = new Error("boom").stack;
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// Unlowered members on lowered containers.
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const sqrt2 = Math.SQRT2;
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// (n-ary Math.min/max LOWER now — the variadic battery lives in the
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// corpus; the mixed spread/positional list is the form that stays fenced.)
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const clamped = Math.min(1, ...[2, 3]);
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const entries = [1, 2].entries();
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const arrAt = [1, 2].at(0);
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const norm = "abc".normalize();
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const limited = "a,b,c".split(",", 2); // the string-separator split lowers; the limit form stays fenced
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const fixed = (1.5).toFixed(); // digit-free toFixed lowers now (the static ties-up integer)
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const localized = (1234.5).toLocaleString();
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// Unlowered call FORMS of lowered members. (push is fully variadic now —
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// no fenced form remains to pin.)
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const nums = [1, 2, 3];
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const found = nums.indexOf(2, 1);
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const joined = nums.join();
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nums.forEach((x) => console.log(x), { unused: true }); // thisArg stays fenced
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const pos = "abc".includes("b", 1); // the position form lowers now (indexOf's clamp)
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const rev = JSON.parse("1", (_k, v) => v);
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// (stringify with a null replacer + LITERAL space now lowers — the pretty
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// battery lives in the corpus; function replacers and non-literal spaces
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// stay fenced.)
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const toStringify = { a: 1 };
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const replaced = JSON.stringify(toStringify, (_k, v) => v);
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const width = 2;
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const spaced = JSON.stringify(toStringify, null, width);
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// The promise surface beyond await.
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async function work(): Promise<number> {
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return 1;
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}
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const thened = work().then((v) => v + 1, () => 0);
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const caught = work().catch(() => 0);
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const resolved = Promise.resolve(1);
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// Object.is lowers over one comparable kind; the unlowered forms fence
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// by name — a validate-first dynamic operand and partially-overlapping
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// unions needing narrowing.
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const dynIs = Object.is(JSON.parse("1") as unknown, 1);
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function pick(a: string | number, b: number | boolean): boolean {
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return Object.is(a, b); // partially-overlapping unions: narrow first
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}
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const picked = pick(1, 2);
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// The binding is READ so the fence stays observable (an unread bigint
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// declaration is a value Node builds and drops — it compiles to nothing).
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const big = 10n;
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console.log(big);
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