Calling a function that returns never, not always triggers an unreachable code error

[gabrielricardourbina]

Bug Report

🔎 Search Terms

• return never
• unreachable code

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about return never & unreachable code

⏯ Playground Link

Playground link with relevant code

💻 Code

declare const blue : (...args: any) => never
declare const hof: (fn :(a: (...args: any) => never) => void ) => void

const withBlue = ()=> {
    blue("test")
    return "OK" // Unreachable code detected
}

const withPink = (pink : (...args: any) => never)=> {
    pink("test")
    return "OK" // Unreachable code detected
}

const withGreen = (unk: unknown) => {
    const green = unk as (...args: any) => never
    green("test")
    return "OK"// Unreachable code NOT detected
}

hof((self)=>{
    self("nahh")
    return "Ok" // Unreachable code NOT detected
})

🙁 Actual behavior

When the function that returns never is inferred, it does not detect unreachable code
When the function that returns has been type-asserted, it does not detect unreachable code

🙂 Expected behavior

Calling a function that returns never should render all code bellow unreachable

[MartinJohns]

It's a known design limitation, see #32695.

A function call is analyzed as an assertion call or never-returning call when

• the call occurs as a top-level expression statement, and
• the call specifies a single identifier or a dotted sequence of identifiers for the function name, and
• each identifier in the function name references an entity with an explicit type, and
• the function name resolves to a function type with an asserts return type or an explicit never return type annotation.

[gabrielricardourbina]

I understand, thanks, should I close this ticket?

[MartinJohns]

Feel free to. Either you do it, or typescript-bot will do it in a few days, as this issue has the duplicate label.