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Rust errors / Types and traits

Rust compiler error · checked with rustc 1.99.0

Rust error E0531: cannot find tuple struct or tuple variant `Type` in this scope

What it meansAn unknown tuple struct/variant has been used.

What rustc prints

error[E0531]: cannot find tuple struct or tuple variant `Type` in this scope
 --> main.rs:3:5
  |
3 | let Type(x) = Type(12); // error!
  |     ^^^^ not found in this scope

Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.

E0531Types and traits
Activein rustc 1.99.0
8related errors linked below

The compiler team's explanation

An unknown tuple struct/variant has been used.

Erroneous code example:

let Type(x) = Type(12); // error!
match Bar(12) {
    Bar(x) => {} // error!
    _ => {}
}

In most cases, it's either a forgotten import or a typo. However, let's look at how you can have such a type:

struct Type(u32); // this is a tuple struct

enum Foo {
    Bar(u32), // this is a tuple variant
}

use Foo::*; // To use Foo's variant directly, we need to import them in
            // the scope.

Either way, it should work fine with our previous code:

struct Type(u32);

enum Foo {
    Bar(u32),
}
use Foo::*;

let Type(x) = Type(12); // ok!
match Type(12) {
    Type(x) => {} // ok!
    _ => {}
}

From rustc --explain E0531 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.

Related errors

All 518 Rust error codes · Rust crate data · Glossary

Up next

Often hit nextE0308: mismatched typesA related error from the same family.Read it next →

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