Closed
Description
Summary
when creating a struct with a min: u8/u16/.. field and using the builder pattern to fill that field with a value of 0, it erroneously emits a unnecessary_min_or_max warning, even though the function is used to set a field on a struct, the struct Parser is not a number so it doesn't make sense for it to "never [be] smaller than 0" and the return value of the min() function is not the same as the input value and is not a number at all.
also, when i run cargo --fix i get this message:
side note: this lint doesn't get triggered with a usize
Lint Name
unnecessary_min_or_max
Reproducer
I tried this code:
use std::str::FromStr;
struct Parser {
/// minimum number of values to parse
min: u16,
}
impl Parser {
fn new() -> Self {
Parser { min: 4 }
}
/// set [`Parser::min`]
fn min(mut self, min: u16) -> Self {
self.min = min;
self
}
fn parse(&self, val: &str) -> Option<Vec<u32>> {
let values = val
.split_whitespace()
.map(u32::from_str)
.map(Result::unwrap)
.collect::<Vec<_>>();
if values.len() < self.min as usize {
None
} else {
Some(values)
}
}
}
fn main() {
let values = Parser::new().min(0).parse("0 1");
dbg!(values);
}I saw this happen:
warning: `Parser::new()` is never smaller than `0` and has therefore no effect
--> src/main.rs:35:15
|
35 | let values = Parser::new().min(0).parse("0 1");
| ^^^^^^^^^^^^^^^^^^^^ help: try: `0`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_min_or_max
= note: `#[warn(clippy::unnecessary_min_or_max)]` on by default
I expected to see this happen:
no warning
Version
rustc 1.82.0-nightly (612a33f20 2024-07-29)
binary: rustc
commit-hash: 612a33f20b9b2c27380edbc4b26a01433ed114bc
commit-date: 2024-07-29
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 18.1.7
Additional Labels
No response