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use super::FOR_KV_MAP;
use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
use clippy_utils::source::snippet;
use clippy_utils::sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::visitors::is_local_used;
use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, Pat, PatKind};
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::sym;
/// Checks for the `FOR_KV_MAP` lint.
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, arg: &'tcx Expr<'_>, body: &'tcx Expr<'_>) {
let pat_span = pat.span;
if let PatKind::Tuple(pat, _) = pat.kind {
if pat.len() == 2 {
let arg_span = arg.span;
let (new_pat_span, kind, ty, mutbl) = match *cx.typeck_results().expr_ty(arg).kind() {
ty::Ref(_, ty, mutbl) => match (&pat[0].kind, &pat[1].kind) {
(key, _) if pat_is_wild(cx, key, body) => (pat[1].span, "value", ty, mutbl),
(_, value) if pat_is_wild(cx, value, body) => (pat[0].span, "key", ty, Mutability::Not),
_ => return,
},
_ => return,
};
let mutbl = match mutbl {
Mutability::Not => "",
Mutability::Mut => "_mut",
};
let arg = match arg.kind {
ExprKind::AddrOf(BorrowKind::Ref, _, expr) => expr,
_ => arg,
};
if is_type_diagnostic_item(cx, ty, sym::HashMap) || is_type_diagnostic_item(cx, ty, sym::BTreeMap) {
span_lint_and_then(
cx,
FOR_KV_MAP,
arg_span,
&format!("you seem to want to iterate on a map's {}s", kind),
|diag| {
let map = sugg::Sugg::hir(cx, arg, "map");
multispan_sugg(
diag,
"use the corresponding method",
vec![
(pat_span, snippet(cx, new_pat_span, kind).into_owned()),
(arg_span, format!("{}.{}s{}()", map.maybe_par(), kind, mutbl)),
],
);
},
);
}
}
}
}
/// Returns `true` if the pattern is a `PatWild` or an ident prefixed with `_`.
fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
match *pat {
PatKind::Wild => true,
PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => !is_local_used(cx, body, id),
_ => false,
}
}
|
