0043ba16b1
Previously, intersections were only allowed as targets, but this was
just an artifact of the original implementation, which operated inside
the structural part of isRelatedTo. Removing this restriction catches
subtle bugs in React user code, where a function named `create` returns
a mapped type whose types are all branded numbers. The display of these
properties, for some original type `T`, is not `number & { __ }` but
the much-less-obvious `RegisteredStyle<T>`.
19 lines
541 B
TypeScript
19 lines
541 B
TypeScript
interface X { x: string }
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interface Y { y: number }
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interface Z { z?: boolean }
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type XY = X & Y;
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const xy: XY = {x: 'x', y: 10};
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const z1: Z = xy; // error, {xy} doesn't overlap with {z}
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interface ViewStyle {
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view: number
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styleMedia: string
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}
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type Brand<T> = number & { __brand: T }
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declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
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const wrapped = create({ first: { view: 0, styleMedia: "???" } });
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const vs: ViewStyle = wrapped.first // error, first is a branded number
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