CODEWITHSUNDEEP
rust
MrSpock
MrSpock

Reputation: 371

Wrong number of lifetime parameters when nesting lifetime inside Vec

I'm trying to build a structure that contains references to a vector of another struct like this:

pub struct Downstream<'a> {
    frequency: i32,
    slot: i32,
    connector: i32,
    description: String,
    cablemac: &'a CableMac,
}

pub struct Upstream<'a> {
    downstreams: Vec<Downstream>,
}

Whatever I try, I always get this lifetime error:

src/e6000/mod.rs:13:22: 13:32 error: wrong number of lifetime parameters: expected 1, found 0 [E0107]
src/e6000/mod.rs:13     downstreams: Vec<Downstream>,

E0107 doesn't help at all.

Where and how so I put an 'a to get this working?

Upvotes: 1

Views: 805

Answers (1)

Dogbert
Dogbert

Reputation: 222328

downstreams: Vec<Downstream>,

should be

downstreams: Vec<Downstream<'a>>,

E0107 doesn't help at all.

You should run rustc --explain E0107.

The output of that command currently starts with some nice examples:

This error means that an incorrect number of lifetime parameters were provided for a type (like a struct or enum) or trait.

Some basic examples include:

struct Foo<'a>(&'a str);
enum Bar { A, B, C }

struct Baz<'a> {
    foo: Foo,     // error: expected 1, found 0
    bar: Bar<'a>, // error: expected 0, found 1
}

Upvotes: 3

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