1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::source::{snippet, snippet_with_applicability};
3 use clippy_utils::{path_def_id, qpath_generic_tys};
4 use rustc_errors::Applicability;
5 use rustc_hir::{self as hir, def_id::DefId, QPath, TyKind};
6 use rustc_lint::LateContext;
7 use rustc_span::symbol::sym;
8 use rustc_hir_analysis::hir_ty_to_ty;
10 use super::{utils, REDUNDANT_ALLOCATION};
12 pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
13 let outer_sym = if Some(def_id) == cx.tcx.lang_items().owned_box() {
15 } else if cx.tcx.is_diagnostic_item(sym::Rc, def_id) {
17 } else if cx.tcx.is_diagnostic_item(sym::Arc, def_id) {
23 if let Some(span) = utils::match_borrows_parameter(cx, qpath) {
24 let mut applicability = Applicability::MaybeIncorrect;
25 let generic_snippet = snippet_with_applicability(cx, span, "..", &mut applicability);
30 &format!("usage of `{}<{}>`", outer_sym, generic_snippet),
32 diag.span_suggestion(hir_ty.span, "try", format!("{}", generic_snippet), applicability);
34 "`{generic}` is already a pointer, `{outer}<{generic}>` allocates a pointer on the heap",
36 generic = generic_snippet
43 let Some(ty) = qpath_generic_tys(qpath).next() else { return false };
44 let Some(id) = path_def_id(cx, ty) else { return false };
45 let (inner_sym, ty) = match cx.tcx.get_diagnostic_name(id) {
46 Some(sym::Arc) => ("Arc", ty),
47 Some(sym::Rc) => ("Rc", ty),
48 _ if Some(id) == cx.tcx.lang_items().owned_box() => ("Box", ty),
52 let inner_qpath = match &ty.kind {
53 TyKind::Path(inner_qpath) => inner_qpath,
56 let inner_span = match qpath_generic_tys(inner_qpath).next() {
58 // Reallocation of a fat pointer causes it to become thin. `hir_ty_to_ty` is safe to use
59 // here because `mod.rs` guarantees this lint is only run on types outside of bodies and
60 // is not run on locals.
61 if !hir_ty_to_ty(cx.tcx, ty).is_sized(cx.tcx.at(ty.span), cx.param_env) {
68 if inner_sym == outer_sym {
69 let mut applicability = Applicability::MaybeIncorrect;
70 let generic_snippet = snippet_with_applicability(cx, inner_span, "..", &mut applicability);
75 &format!("usage of `{}<{}<{}>>`", outer_sym, inner_sym, generic_snippet),
80 format!("{}<{}>", outer_sym, generic_snippet),
84 "`{inner}<{generic}>` is already on the heap, `{outer}<{inner}<{generic}>>` makes an extra allocation",
87 generic = generic_snippet
92 let generic_snippet = snippet(cx, inner_span, "..");
97 &format!("usage of `{}<{}<{}>>`", outer_sym, inner_sym, generic_snippet),
100 "`{inner}<{generic}>` is already on the heap, `{outer}<{inner}<{generic}>>` makes an extra allocation",
103 generic = generic_snippet
106 "consider using just `{outer}<{generic}>` or `{inner}<{generic}>`",
109 generic = generic_snippet