1 use super::utils::clone_or_copy_needed;
2 use clippy_utils::diagnostics::span_lint_and_then;
3 use clippy_utils::higher::ForLoop;
4 use clippy_utils::source::snippet_opt;
5 use clippy_utils::ty::{get_iterator_item_ty, implements_trait};
6 use clippy_utils::{fn_def_id, get_parent_expr};
7 use rustc_errors::Applicability;
8 use rustc_hir::{def_id::DefId, Expr, ExprKind};
9 use rustc_lint::LateContext;
10 use rustc_span::{sym, Symbol};
12 use super::UNNECESSARY_TO_OWNED;
14 pub fn check(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol, receiver: &Expr<'_>) -> bool {
16 if let Some(parent) = get_parent_expr(cx, expr);
17 if let Some(callee_def_id) = fn_def_id(cx, parent);
18 if is_into_iter(cx, callee_def_id);
20 check_for_loop_iter(cx, parent, method_name, receiver, false)
27 /// Checks whether `expr` is an iterator in a `for` loop and, if so, determines whether the
28 /// iterated-over items could be iterated over by reference. The reason why `check` above does not
29 /// include this code directly is so that it can be called from
30 /// `unnecessary_into_owned::check_into_iter_call_arg`.
31 pub fn check_for_loop_iter(
36 cloned_before_iter: bool,
39 if let Some(grandparent) = get_parent_expr(cx, expr).and_then(|parent| get_parent_expr(cx, parent));
40 if let Some(ForLoop { pat, body, .. }) = ForLoop::hir(grandparent);
41 let (clone_or_copy_needed, addr_of_exprs) = clone_or_copy_needed(cx, pat, body);
42 if !clone_or_copy_needed;
43 if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
45 let snippet = if_chain! {
46 if let ExprKind::MethodCall(maybe_iter_method_name, collection, [], _) = receiver.kind;
47 if maybe_iter_method_name.ident.name == sym::iter;
49 if let Some(iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
50 let receiver_ty = cx.typeck_results().expr_ty(receiver);
51 if implements_trait(cx, receiver_ty, iterator_trait_id, &[]);
52 if let Some(iter_item_ty) = get_iterator_item_ty(cx, receiver_ty);
54 if let Some(into_iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::IntoIterator);
55 let collection_ty = cx.typeck_results().expr_ty(collection);
56 if implements_trait(cx, collection_ty, into_iterator_trait_id, &[]);
57 if let Some(into_iter_item_ty) = cx.get_associated_type(collection_ty, into_iterator_trait_id, "Item");
59 if iter_item_ty == into_iter_item_ty;
60 if let Some(collection_snippet) = snippet_opt(cx, collection.span);
71 &format!("unnecessary use of `{method_name}`"),
73 // If `check_into_iter_call_arg` called `check_for_loop_iter` because a call to
74 // a `to_owned`-like function was removed, then the next suggestion may be
75 // incorrect. This is because the iterator that results from the call's removal
76 // could hold a reference to a resource that is used mutably. See
77 // https://github.com/rust-lang/rust-clippy/issues/8148.
78 let applicability = if cloned_before_iter {
79 Applicability::MaybeIncorrect
81 Applicability::MachineApplicable
83 diag.span_suggestion(expr.span, "use", snippet, applicability);
84 for addr_of_expr in addr_of_exprs {
85 match addr_of_expr.kind {
86 ExprKind::AddrOf(_, _, referent) => {
87 let span = addr_of_expr.span.with_hi(referent.span.lo());
88 diag.span_suggestion(span, "remove this `&`", "", applicability);
101 /// Returns true if the named method is `IntoIterator::into_iter`.
102 pub fn is_into_iter(cx: &LateContext<'_>, callee_def_id: DefId) -> bool {
103 Some(callee_def_id) == cx.tcx.lang_items().into_iter_fn()