mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-24 06:14:01 +08:00
Chris Tate
1f10e83720
- Preserve callback identity, receiver binding, and class references across unions and collections. - Track record field presence independently of undefined values and improve native runtime behavior. - Expand differential coverage and streamline CI bootstrap and compiler rebuild checks.
31 lines
1.2 KiB
TypeScript
31 lines
1.2 KiB
TypeScript
// A non-null assertion has no runtime effect: an out-of-range read stays
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// undefined wherever array storage, an equality test, or an optional slot
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// receives it.
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class Child {
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v = 1;
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}
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const kids: Child[] = [new Child()];
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const a = [kids[5]!];
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console.log(a.length, a[0] === undefined);
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const typed: Child[] = [kids[7]!, kids[0]!];
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console.log(typed.length, typed[0] === undefined, typed[1] === kids[0]);
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const later: Child[] = [];
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later.push(kids[3]!);
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later.unshift(kids[4]!);
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later[2] = kids[0]!;
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later[3] = kids[8]!;
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console.log(later.length, later[0] === undefined, later[1] === undefined, later[2] === kids[0], later[3] === undefined);
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function describe(c: Child | undefined): string {
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return c === undefined ? "missing" : "present " + c.v;
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}
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console.log(describe(kids[9]!), describe(kids[0]!));
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const nums = [1, 2];
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const b = [nums[4]!, nums[0]!];
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console.log(b.length, b[0] === undefined, b[1]);
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const words = ["x"];
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const c = [(words[2]!), words[0]!];
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console.log(c.length, c[0] === undefined, c[1], c.join("-"));
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const xs = [1, 2, 3];
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console.log(xs[3]! === undefined, xs[0]! === undefined, xs[5]! !== undefined, xs[1]! === 2);
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console.log(kids[4]! === undefined, undefined === kids[4]!, kids[0]! === kids[0], kids[2]! == null);
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