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A pattern attempted to extract an incorrect number of fields from a variant.
Erroneous code example:
```compile_fail,E0023
enum Fruit {
Apple(String, String),
Pear(u32),
}
let x = Fruit::Apple(String::new(), String::new());
match x {
Fruit::Apple(a) => {}, // error!
_ => {}
}
```
A pattern used to match against an enum variant must provide a sub-pattern for
each field of the enum variant.
Here the `Apple` variant has two fields, and should be matched against like so:
```
enum Fruit {
Apple(String, String),
Pear(u32),
}
let x = Fruit::Apple(String::new(), String::new());
// Correct.
match x {
Fruit::Apple(a, b) => {},
_ => {}
}
```
Matching with the wrong number of fields has no sensible interpretation:
```compile_fail,E0023
enum Fruit {
Apple(String, String),
Pear(u32),
}
let x = Fruit::Apple(String::new(), String::new());
// Incorrect.
match x {
Fruit::Apple(a) => {},
Fruit::Apple(a, b, c) => {},
}
```
Check how many fields the enum was declared with and ensure that your pattern
uses the same number.
|
