1 use crate::consts::constant_simple;
3 use crate::utils::sugg;
4 use if_chain::if_chain;
5 use rustc_errors::Applicability;
6 use rustc_hir::{def, Arm, Expr, ExprKind, Pat, 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};
13 declare_clippy_lint! {
15 /// Finds patterns that reimplement `Option::unwrap_or` or `Result::unwrap_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;
33 /// let foo: Option<i32> = None;
38 "finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`"
41 declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
43 impl LateLintPass<'_> for ManualUnwrapOr {
44 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
45 if in_external_macro(cx.sess(), expr.span) {
48 lint_manual_unwrap_or(cx, expr);
52 #[derive(Copy, Clone)]
59 fn unwrap_fn_path(&self) -> &str {
61 Case::Option => "Option::unwrap_or",
62 Case::Result => "Result::unwrap_or",
67 fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
68 fn applicable_or_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
71 if arms.iter().all(|arm| arm.guard.is_none());
72 if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)|
74 PatKind::Path(ref some_qpath) =>
75 utils::match_qpath(some_qpath, &utils::paths::OPTION_NONE),
76 PatKind::TupleStruct(ref err_qpath, &[Pat { kind: PatKind::Wild, .. }], _) =>
77 utils::match_qpath(err_qpath, &utils::paths::RESULT_ERR),
81 let unwrap_arm = &arms[1 - idx];
82 if let PatKind::TupleStruct(ref unwrap_qpath, &[unwrap_pat], _) = unwrap_arm.pat.kind;
83 if utils::match_qpath(unwrap_qpath, &utils::paths::OPTION_SOME)
84 || utils::match_qpath(unwrap_qpath, &utils::paths::RESULT_OK);
85 if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
86 if let ExprKind::Path(QPath::Resolved(_, body_path)) = unwrap_arm.body.kind;
87 if let def::Res::Local(body_path_hir_id) = body_path.res;
88 if body_path_hir_id == binding_hir_id;
89 if !utils::usage::contains_return_break_continue_macro(or_arm.body);
99 if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
100 let ty = cx.typeck_results().expr_ty(scrutinee);
101 if let Some(case) = if utils::is_type_diagnostic_item(cx, ty, sym::option_type) {
103 } else if utils::is_type_diagnostic_item(cx, ty, sym::result_type) {
108 if let Some(or_arm) = applicable_or_arm(match_arms);
109 if let Some(or_body_snippet) = utils::snippet_opt(cx, or_arm.body.span);
110 if let Some(indent) = utils::indent_of(cx, expr.span);
111 if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some();
113 let reindented_or_body =
114 utils::reindent_multiline(or_body_snippet.into(), true, Some(indent));
115 utils::span_lint_and_sugg(
117 MANUAL_UNWRAP_OR, expr.span,
118 &format!("this pattern reimplements `{}`", case.unwrap_fn_path()),
122 sugg::Sugg::hir(cx, scrutinee, "..").maybe_par(),
125 Applicability::MachineApplicable,