Spurious "referenced directly or indirectly in its own initializer" when combined with narrowing, asserts function, and loop

Bug Report

🔎 Search Terms

referenced directly or indirectly asserts

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground Link

💻 Code

declare const myRequire: ((p: string) => {} | undefined) | undefined;

declare function assertIsDefined<T>(value: T): asserts value is NonNullable<T>

function fn1() {
    if (!myRequire) {
        return;
    }

    for (const p of ["a", "b"]) {
        // Error?
        const result = myRequire("something");
        assertIsDefined(result);
    }
}

🙁 Actual behavior

result is claimed to be referenced directly or indirectly in its initializer.

Modifying the code in various ways makes the error go away.

🙂 Expected behavior

No error; there's no relationship between the initializer and the result.

从链接的 TypeScript Playground 开始，运行提供的代码示例以复现该诊断。调查编译器如何处理 narrowing、asserts functions 以及 initializer 周围的循环。当示例不再报告 result 在其自身的 initializer 中被引用，同时预期的 narrowing 行为仍保持不变时，即表示完成。