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