Identical Or patterns

What it does

In pattern matching, if you write Pattern | Pattern => ... then it should suggest writing Pattern => .... Duplicating a pattern twice in an Or pattern is unnecessary.

Advantage

• Reduces the amount of code.
• In many cases will spot bugs, when the code was meant to be different.

Drawbacks

None I can think of.

Example

match x {
    (Ty::Tuple(_), _) | (Ty::Tuple(_), _) => true,
    _ => false,
}

Could be written as:

match x {
    (Ty::Tuple(_), _) => true,
    _ => false,
}

The issue provides no source file or test entry point; begin by locating Clippy’s pattern-matching lint code and its regression tests. Use the supplied Rust match example as the starting case, and consider the work complete when identical alternatives in an Or pattern are diagnosed while the simplified form remains valid.