Redundant if test lint

What it does

Here the first if test contains a return so the second if can't be true. This is usually a coding mistake that could hide a bug, so I think a lint that spots such situations is good. This lint could be complex (like firing even if the first test contains "< 3") but even basic cases like this with repeated conditions should be useful.

Lint Name

impossibile_if_branch

Category

suspicious

Advantage

No response

Drawbacks

No response

Example

fn test2(s: &[u32]) -> bool {
    if s.len() < 2 {
        return true;
    }
    
    if s.len() < 2 {
        println!("*");
    }
    false
}

No implementation files or tests are named in the issue. Start by locating Clippy's existing suspicious lints and their test conventions, then use the Rust example as the initial acceptance case: repeated conditions after a returning branch should be reported without incorrectly flagging valid control flow.