Properly handle co- and contra-variant inferences in strict mode #26566
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| >f2 : <T>(obj: T, f1: (x: T) => void, f2: (x: T) => void) => T | ||
| >"abc" : "abc" | ||
| >fo : (x: Object) => void | ||
| >fs : (x: string) => void | ||
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| const x3 = f3("abc", fo, fx); // "abc" | "def" | ||
| >x3 : Object | ||
| >f3("abc", fo, fx) : Object | ||
| >x3 : "def" | "abc" |
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We should discuss this later, but this inference seems bad
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No, this inference is correct. The fx argument is a function taking a function, and since contra-contra-variant is the same as co-variant, we make two co-variant inferences, "abc" and "def". Per normal rules we union together literal inferences for the same type parameter, so we end up with "abc" | "def".
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Missed the double 180; you're right
RyanCavanaugh
approved these changes
Aug 21, 2018
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Fixes #26127.