rust-clippy/clippy_lints/src/methods/iter_skip_next.rs

use crate::utils::{match_trait_method, paths, snippet, span_lint_and_sugg};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;

use super::ITER_SKIP_NEXT;

pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, skip_args: &[hir::Expr<'_>]) {
    // lint if caller of skip is an Iterator
    if match_trait_method(cx, expr, &paths::ITERATOR) {
        if let [caller, n] = skip_args {
            let hint = format!(".nth({})", snippet(cx, n.span, ".."));
            span_lint_and_sugg(
                cx,
                ITER_SKIP_NEXT,
                expr.span.trim_start(caller.span).unwrap(),
                "called `skip(..).next()` on an iterator",
                "use `nth` instead",
                hint,
                Applicability::MachineApplicable,
            );
        }
    }
}