SeaQL/sea-orm · info

Infallible

Error message

Infallible

What it means

In `Identity::quoted()` (the `to_string` path), `write!` into a `String` can only fail if the underlying formatter errors, which cannot happen for `String` targets — hence `.expect("Infallible")`. This is a standard Rust idiom for marking `fmt::Write` results as impossible to fail; it is effectively unreachable for library users.

Source

Thrown at sea-orm-sync/src/entity/identity.rs:79

    fn into_iter(self) -> Self::IntoIter {
        OwnedIdentityIter {
            identity: self,
            index: 0,
        }
    }
}

impl Iden for Identity {
    fn quoted(&self) -> Cow<'static, str> {
        match self {
            Identity::Unary(iden) => iden.inner(),
            Identity::Binary(iden1, iden2) => Cow::Owned(format!("{iden1}{iden2}")),
            Identity::Ternary(iden1, iden2, iden3) => Cow::Owned(format!("{iden1}{iden2}{iden3}")),
            Identity::Many(vec) => {
                let mut s = String::new();
                for iden in vec.iter() {
                    write!(&mut s, "{iden}").expect("Infallible");
                }
                Cow::Owned(s)
            }
        }
    }

    fn to_string(&self) -> String {
        match self.quoted() {
            Cow::Borrowed(s) => s.to_owned(),
            Cow::Owned(s) => s,
        }
    }

    fn unquoted(&self) -> &str {
        panic!("Should not call this")
    }
}

View on GitHub (pinned to e29bcd1b41)

Solutions

1. No user action required; treat as an unreachable internal assertion.
2. If ever observed, it indicates memory exhaustion — reduce memory pressure.

catch_unwind(|| identity.quoted()) // effectively unreachable; no handling needed

When it happens

Trigger: Only reachable when stringifying an `Identity::Many` identifier. With `std::io::Write` this could fail on OOM/allocation failure, but for `String` formatting it is unconditionally successful.

Common situations: Practically never hit by users; would only surface under allocator failure during debug printing of identifiers.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• Failed to get numeric array
• Failed to get oid
• Failed to get oid array
• Failed to get json
• Failed to get json array

AI-assisted analysis of SeaQL/sea-orm@e29bcd1b41 (2026-09-10). Data as JSON: /api/errors/505df435b8d2f56c. Report an issue: GitHub.