2 indent_of, is_type_diagnostic_item, match_qpath, paths, reindent_multiline, snippet_opt, span_lint_and_sugg,
4 use if_chain::if_chain;
5 use rustc_errors::Applicability;
6 use rustc_hir::{def, Expr, ExprKind, PatKind, QPath};
7 use rustc_lint::LintContext;
8 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_middle::lint::in_external_macro;
10 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 use rustc_span::symbol::sym;
13 declare_clippy_lint! {
15 /// Finds patterns that reimplement `Option::ok_or`.
17 /// **Why is this bad?**
18 /// Concise code helps focusing on behavior instead of boilerplate.
20 /// **Known problems:** None.
24 /// let foo: Option<i32> = None;
25 /// foo.map_or(Err("error"), |v| Ok(v));
30 /// let foo: Option<i32> = None;
31 /// foo.ok_or("error");
35 "finds patterns that can be encoded more concisely with `Option::ok_or`"
38 declare_lint_pass!(ManualOkOr => [MANUAL_OK_OR]);
40 impl LateLintPass<'_> for ManualOkOr {
41 fn check_expr(&mut self, cx: &LateContext<'tcx>, scrutinee: &'tcx Expr<'tcx>) {
42 if in_external_macro(cx.sess(), scrutinee.span) {
47 if let ExprKind::MethodCall(method_segment, _, args, _) = scrutinee.kind;
48 if method_segment.ident.name == sym!(map_or);
50 let method_receiver = &args[0];
51 let ty = cx.typeck_results().expr_ty(method_receiver);
52 if is_type_diagnostic_item(cx, ty, sym::option_type);
53 let or_expr = &args[1];
54 if is_ok_wrapping(cx, &args[2]);
55 if let ExprKind::Call(Expr { kind: ExprKind::Path(err_path), .. }, &[ref err_arg]) = or_expr.kind;
56 if match_qpath(err_path, &paths::RESULT_ERR);
57 if let Some(method_receiver_snippet) = snippet_opt(cx, method_receiver.span);
58 if let Some(err_arg_snippet) = snippet_opt(cx, err_arg.span);
59 if let Some(indent) = indent_of(cx, scrutinee.span);
61 let reindented_err_arg_snippet =
62 reindent_multiline(err_arg_snippet.into(), true, Some(indent + 4));
67 "this pattern reimplements `Option::ok_or`",
71 method_receiver_snippet,
72 reindented_err_arg_snippet
74 Applicability::MachineApplicable,
81 fn is_ok_wrapping(cx: &LateContext<'_>, map_expr: &Expr<'_>) -> bool {
82 if let ExprKind::Path(ref qpath) = map_expr.kind {
83 if match_qpath(qpath, &paths::RESULT_OK) {
88 if let ExprKind::Closure(_, _, body_id, ..) = map_expr.kind;
89 let body = cx.tcx.hir().body(body_id);
90 if let PatKind::Binding(_, param_id, ..) = body.params[0].pat.kind;
91 if let ExprKind::Call(Expr { kind: ExprKind::Path(ok_path), .. }, &[ref ok_arg]) = body.value.kind;
92 if match_qpath(ok_path, &paths::RESULT_OK);
93 if let ExprKind::Path(QPath::Resolved(_, ok_arg_path)) = ok_arg.kind;
94 if let def::Res::Local(ok_arg_path_id) = ok_arg_path.res;
95 then { param_id == ok_arg_path_id } else { false }