19 lines
777 B
TypeScript
19 lines
777 B
TypeScript
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// https://github.com/Microsoft/TypeScript/issues/19632
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declare function direct<A extends string>(a: A | A[]): Record<A, string>
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declare function nested<A extends string>(a: { fields: A }): Record<A, string>
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declare function nestedUnion<A extends string>(a: { fields: A | A[] }): Record<A, string>
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const directUnionSingle = direct("z")
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const directUnionArray = direct(["z", "y"])
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const nestedSingle = nested({fields: "z"})
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const nestedUnionSingle = nestedUnion({fields: "z"})
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const nestedUnionArray = nestedUnion({fields: ["z", "y"]})
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declare function hasZField(arg: { z: string }): void
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hasZField(directUnionSingle) // ok
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hasZField(directUnionArray) // ok
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hasZField(nestedSingle) // ok
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hasZField(nestedUnionSingle) // ok
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hasZField(nestedUnionArray) // ok
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