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};
12 declare_clippy_lint! {
14 /// Finds patterns that reimplement `Option::ok_or`.
16 /// **Why is this bad?**
17 /// Concise code helps focusing on behavior instead of boilerplate.
19 /// **Known problems:** None.
23 /// let foo: Option<i32> = None;
24 /// foo.map_or(Err("error"), |v| Ok(v));
26 /// let foo: Option<i32> = None;
27 /// foo.map_or(Err("error"), |v| Ok(v));
32 /// let foo: Option<i32> = None;
33 /// foo.ok_or("error");
37 "finds patterns that can be encoded more concisely with `Option::ok_or`"
40 declare_lint_pass!(ManualOkOr => [MANUAL_OK_OR]);
42 impl LateLintPass<'_> for ManualOkOr {
43 fn check_expr(&mut self, cx: &LateContext<'tcx>, scrutinee: &'tcx Expr<'tcx>) {
44 if in_external_macro(cx.sess(), scrutinee.span) {
49 if let ExprKind::MethodCall(method_segment, _, args, _) = scrutinee.kind;
50 if method_segment.ident.name == sym!(map_or);
52 let method_receiver = &args[0];
53 let ty = cx.typeck_results().expr_ty(method_receiver);
54 if is_type_diagnostic_item(cx, ty, sym!(option_type));
55 let or_expr = &args[1];
56 if is_ok_wrapping(cx, &args[2]);
57 if let ExprKind::Call(Expr { kind: ExprKind::Path(err_path), .. }, &[ref err_arg]) = or_expr.kind;
58 if match_qpath(err_path, &paths::RESULT_ERR);
59 if let Some(method_receiver_snippet) = snippet_opt(cx, method_receiver.span);
60 if let Some(err_arg_snippet) = snippet_opt(cx, err_arg.span);
61 if let Some(indent) = indent_of(cx, scrutinee.span);
63 let reindented_err_arg_snippet =
64 reindent_multiline(err_arg_snippet.into(), true, Some(indent + 4));
69 "this pattern reimplements `Option::ok_or`",
73 method_receiver_snippet,
74 reindented_err_arg_snippet
76 Applicability::MachineApplicable,
83 fn is_ok_wrapping(cx: &LateContext<'_>, map_expr: &Expr<'_>) -> bool {
84 if let ExprKind::Path(ref qpath) = map_expr.kind {
85 if match_qpath(qpath, &paths::RESULT_OK) {
90 if let ExprKind::Closure(_, _, body_id, ..) = map_expr.kind;
91 let body = cx.tcx.hir().body(body_id);
92 if let PatKind::Binding(_, param_id, ..) = body.params[0].pat.kind;
93 if let ExprKind::Call(Expr { kind: ExprKind::Path(ok_path), .. }, &[ref ok_arg]) = body.value.kind;
94 if match_qpath(ok_path, &paths::RESULT_OK);
95 if let ExprKind::Path(QPath::Resolved(_, ok_arg_path)) = ok_arg.kind;
96 if let def::Res::Local(ok_arg_path_id) = ok_arg_path.res;
97 then { param_id == ok_arg_path_id } else { false }