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Chris Tate
85fe87ffbf
A TypeScript Date placed in an `unknown` slot (an annotated binding, an object or array literal, a record or class field) becomes a Date holding the same time value. Before, a Date member of an `unknown` object literal became a function, and other conversions were refused. util.inspect prints these Dates in their ISO form or as Invalid Date, and their methods can be read as values through untyped references. Comparisons with a Date operand keep their fence: each conversion creates a new Date.
24 lines
1.2 KiB
TypeScript
24 lines
1.2 KiB
TypeScript
// The fences around utility-type record shapes. Utility types over data
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// shapes compile (Partial/Record/Pick/Omit/Readonly resolve to ordinary
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// record shapes — differential corpus), and STRING and NUMBER index
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// signatures over supported value types compile as hybrid shapes (declared
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// fields + an overflow map; number keys canonicalize to their JS string
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// spelling; function/Map/Set/nested-record values ride the same store —
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// differential corpus); what stays rejected:
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// - symbol-keyed index signatures (no lowering for symbol keys);
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// - index-signature value types outside the overflow-map slice (Dates and
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// other lib API objects, even when the value itself has a representation).
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// (Readonly<Date> bindings compile, holding the Date as a checked value.
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// Dot access/writes to index-signature keys compile now — the overflow
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// path in dot spelling — and self-referential mapped types intern as
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// named recursive shapes; differential corpus covers both.)
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const bySymbol: { [s: symbol]: string } = {};
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console.log(bySymbol);
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const dateBag: { [k: string]: Date } = {};
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const boot = dateBag["boot"];
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console.log(boot);
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const stamped: Readonly<Date> = new Date(0);
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console.log(stamped.getTime());
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