1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::source::{snippet, snippet_with_applicability};
3 use clippy_utils::{get_qpath_generic_tys, is_ty_param_diagnostic_item, is_ty_param_lang_item};
4 use rustc_errors::Applicability;
5 use rustc_hir::{self as hir, def_id::DefId, LangItem, QPath, TyKind};
6 use rustc_lint::LateContext;
7 use rustc_span::symbol::sym;
9 use super::{utils, REDUNDANT_ALLOCATION};
11 pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
12 let outer_sym = if Some(def_id) == cx.tcx.lang_items().owned_box() {
14 } else if cx.tcx.is_diagnostic_item(sym::Rc, def_id) {
16 } else if cx.tcx.is_diagnostic_item(sym::Arc, def_id) {
22 if let Some(span) = utils::match_borrows_parameter(cx, qpath) {
23 let mut applicability = Applicability::MaybeIncorrect;
24 let generic_snippet = snippet_with_applicability(cx, span, "..", &mut applicability);
29 &format!("usage of `{}<{}>`", outer_sym, generic_snippet),
31 diag.span_suggestion(hir_ty.span, "try", format!("{}", generic_snippet), applicability);
33 "`{generic}` is already a pointer, `{outer}<{generic}>` allocates a pointer on the heap",
35 generic = generic_snippet
42 let (inner_sym, ty) = if let Some(ty) = is_ty_param_lang_item(cx, qpath, LangItem::OwnedBox) {
44 } else if let Some(ty) = is_ty_param_diagnostic_item(cx, qpath, sym::Rc) {
46 } else if let Some(ty) = is_ty_param_diagnostic_item(cx, qpath, sym::Arc) {
52 let inner_qpath = match &ty.kind {
53 TyKind::Path(inner_qpath) => inner_qpath,
56 let inner_span = match get_qpath_generic_tys(inner_qpath).next() {
60 if inner_sym == outer_sym {
61 let mut applicability = Applicability::MaybeIncorrect;
62 let generic_snippet = snippet_with_applicability(cx, inner_span, "..", &mut applicability);
67 &format!("usage of `{}<{}<{}>>`", outer_sym, inner_sym, generic_snippet),
72 format!("{}<{}>", outer_sym, generic_snippet),
76 "`{inner}<{generic}>` is already on the heap, `{outer}<{inner}<{generic}>>` makes an extra allocation",
79 generic = generic_snippet
84 let generic_snippet = snippet(cx, inner_span, "..");
89 &format!("usage of `{}<{}<{}>>`", outer_sym, inner_sym, generic_snippet),
92 "`{inner}<{generic}>` is already on the heap, `{outer}<{inner}<{generic}>>` makes an extra allocation",
95 generic = generic_snippet
98 "consider using just `{outer}<{generic}>` or `{inner}<{generic}>`",
101 generic = generic_snippet