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Control Flow Analysis for Dependent Parameters generic
v4.7.0-dev.20220302
Playground link with relevant code
type Func = <T extends ["a", number] | ["b", string]>(...args: T) => void; const f1: Func = (kind, payload) => { if (kind === "a") { payload.toFixed(); // error } if (kind === "b") { payload.toUpperCase(); // error } };
parameter type not narrowed
parameter type is narrowed, like in the example from the typescript 4.6 blog post
type Func = (...args: ["a", number] | ["b", string]) => void; const f1: Func = (kind, payload) => { if (kind === "a") { payload.toFixed(); // 'payload' narrowed to 'number' } if (kind === "b") { payload.toUpperCase(); // 'payload' narrowed to 'string' } }; f1("a", 42); f1("b", "hello");
Bug Report
🔎 Search Terms
Control Flow Analysis for Dependent Parameters generic
🕗 Version & Regression Information
v4.7.0-dev.20220302
⏯ Playground Link
Playground link with relevant code
💻 Code
🙁 Actual behavior
parameter type not narrowed
🙂 Expected behavior
parameter type is narrowed, like in the example from the typescript 4.6 blog post