1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
use clippy_utils::source::snippet;
use clippy_utils::ty::implements_trait;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::sym;
use super::FILTER_NEXT;
/// lint use of `filter().next()` for `Iterators`
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'_>,
recv: &'tcx hir::Expr<'_>,
filter_arg: &'tcx hir::Expr<'_>,
) {
// lint if caller of `.filter().next()` is an Iterator
let recv_impls_iterator = cx.tcx.get_diagnostic_item(sym::Iterator).map_or(false, |id| {
implements_trait(cx, cx.typeck_results().expr_ty(recv), id, &[])
});
if recv_impls_iterator {
let msg = "called `filter(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
`.find(..)` instead";
let filter_snippet = snippet(cx, filter_arg.span, "..");
if filter_snippet.lines().count() <= 1 {
let iter_snippet = snippet(cx, recv.span, "..");
// add note if not multi-line
span_lint_and_sugg(
cx,
FILTER_NEXT,
expr.span,
msg,
"try this",
format!("{iter_snippet}.find({filter_snippet})"),
Applicability::MachineApplicable,
);
} else {
span_lint(cx, FILTER_NEXT, expr.span, msg);
}
}
}
|
