multiple return values without a tuple return type

Why this fires¶

A function's declared return type is a single (non-tuple) type — -> T, or no annotation at all — but one of its return statements returns more than one value.

fn pair() -> int {
    return 1, 2
    //     ^^^^ error[TE007]: function 'pair' returns 2 value(s) but only 1 is expected;
    //          use -> (T1, T2, ...) to declare a multi-return
}

Fix it¶

1. Declare a tuple return type¶

If the function is meant to return multiple values, say so in the signature:

fn pair() -> (int, int) {
    return 1, 2             // ok
}

2. Return a single value¶

If only one value was intended, drop the rest:

fn pair() -> int {
    return 1                // ok
}

See also¶

• TE006 — the opposite mismatch: a tuple-typed function returning the wrong number of values.
• /docs/functions — multi-return functions.