1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::source::snippet;
3 use clippy_utils::ty::is_type_diagnostic_item;
4 use clippy_utils::{match_def_path, meets_msrv, msrvs, path_to_local_id, paths, remove_blocks};
5 use if_chain::if_chain;
6 use rustc_errors::Applicability;
8 use rustc_lint::LateContext;
10 use rustc_semver::RustcVersion;
13 use super::OPTION_AS_REF_DEREF;
15 /// lint use of `_.as_ref().map(Deref::deref)` for `Option`s
16 pub(super) fn check<'tcx>(
17 cx: &LateContext<'tcx>,
19 as_ref_recv: &hir::Expr<'_>,
20 map_arg: &hir::Expr<'_>,
22 msrv: Option<&RustcVersion>,
24 if !meets_msrv(msrv, &msrvs::OPTION_AS_DEREF) {
28 let same_mutability = |m| (is_mut && m == &hir::Mutability::Mut) || (!is_mut && m == &hir::Mutability::Not);
30 let option_ty = cx.typeck_results().expr_ty(as_ref_recv);
31 if !is_type_diagnostic_item(cx, option_ty, sym::option_type) {
35 let deref_aliases: [&[&str]; 9] = [
36 &paths::DEREF_TRAIT_METHOD,
37 &paths::DEREF_MUT_TRAIT_METHOD,
38 &paths::CSTRING_AS_C_STR,
39 &paths::OS_STRING_AS_OS_STR,
40 &paths::PATH_BUF_AS_PATH,
41 &paths::STRING_AS_STR,
42 &paths::STRING_AS_MUT_STR,
44 &paths::VEC_AS_MUT_SLICE,
47 let is_deref = match map_arg.kind {
48 hir::ExprKind::Path(ref expr_qpath) => cx
49 .qpath_res(expr_qpath, map_arg.hir_id)
51 .map_or(false, |fun_def_id| {
52 deref_aliases.iter().any(|path| match_def_path(cx, fun_def_id, path))
54 hir::ExprKind::Closure(_, _, body_id, _, _) => {
55 let closure_body = cx.tcx.hir().body(body_id);
56 let closure_expr = remove_blocks(&closure_body.value);
58 match &closure_expr.kind {
59 hir::ExprKind::MethodCall(_, _, args, _) => {
62 if path_to_local_id(&args[0], closure_body.params[0].pat.hir_id);
65 .expr_adjustments(&args[0])
68 .collect::<Box<[_]>>();
69 if let [ty::adjustment::Adjust::Deref(None), ty::adjustment::Adjust::Borrow(_)] = *adj;
71 let method_did = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id).unwrap();
72 deref_aliases.iter().any(|path| match_def_path(cx, method_did, path))
78 hir::ExprKind::AddrOf(hir::BorrowKind::Ref, m, inner) if same_mutability(m) => {
80 if let hir::ExprKind::Unary(hir::UnOp::Deref, inner1) = inner.kind;
81 if let hir::ExprKind::Unary(hir::UnOp::Deref, inner2) = inner1.kind;
83 path_to_local_id(inner2, closure_body.params[0].pat.hir_id)
96 let current_method = if is_mut {
97 format!(".as_mut().map({})", snippet(cx, map_arg.span, ".."))
99 format!(".as_ref().map({})", snippet(cx, map_arg.span, ".."))
101 let method_hint = if is_mut { "as_deref_mut" } else { "as_deref" };
102 let hint = format!("{}.{}()", snippet(cx, as_ref_recv.span, ".."), method_hint);
103 let suggestion = format!("try using {} instead", method_hint);
106 "called `{0}` on an Option value. This can be done more directly \
107 by calling `{1}` instead",
117 Applicability::MachineApplicable,