1 use clippy_utils::consts::constant_simple;
2 use clippy_utils::diagnostics::span_lint_and_sugg;
3 use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt};
4 use clippy_utils::ty::is_type_diagnostic_item;
5 use clippy_utils::usage::contains_return_break_continue_macro;
6 use clippy_utils::{in_constant, is_lang_ctor, path_to_local_id, sugg};
7 use if_chain::if_chain;
8 use rustc_errors::Applicability;
9 use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk};
10 use rustc_hir::{Arm, Expr, ExprKind, PatKind};
11 use rustc_lint::LintContext;
12 use rustc_lint::{LateContext, LateLintPass};
13 use rustc_middle::lint::in_external_macro;
14 use rustc_session::{declare_lint_pass, declare_tool_lint};
17 declare_clippy_lint! {
19 /// Finds patterns that reimplement `Option::unwrap_or` or `Result::unwrap_or`.
21 /// ### Why is this bad?
22 /// Concise code helps focusing on behavior instead of boilerplate.
26 /// let foo: Option<i32> = None;
35 /// let foo: Option<i32> = None;
40 "finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`"
43 declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
45 impl LateLintPass<'_> for ManualUnwrapOr {
46 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
47 if in_external_macro(cx.sess(), expr.span) || in_constant(cx, expr.hir_id) {
50 lint_manual_unwrap_or(cx, expr);
54 fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
55 fn applicable_or_arm<'a>(cx: &LateContext<'_>, arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
58 if arms.iter().all(|arm| arm.guard.is_none());
59 if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)| {
61 PatKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone),
62 PatKind::TupleStruct(ref qpath, [pat], _) =>
63 matches!(pat.kind, PatKind::Wild) && is_lang_ctor(cx, qpath, ResultErr),
67 let unwrap_arm = &arms[1 - idx];
68 if let PatKind::TupleStruct(ref qpath, [unwrap_pat], _) = unwrap_arm.pat.kind;
69 if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk);
70 if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
71 if path_to_local_id(unwrap_arm.body, binding_hir_id);
72 if cx.typeck_results().expr_adjustments(unwrap_arm.body).is_empty();
73 if !contains_return_break_continue_macro(or_arm.body);
83 if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
84 let ty = cx.typeck_results().expr_ty(scrutinee);
85 if let Some(ty_name) = if is_type_diagnostic_item(cx, ty, sym::Option) {
87 } else if is_type_diagnostic_item(cx, ty, sym::Result) {
92 if let Some(or_arm) = applicable_or_arm(cx, match_arms);
93 if let Some(or_body_snippet) = snippet_opt(cx, or_arm.body.span);
94 if let Some(indent) = indent_of(cx, expr.span);
95 if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some();
97 let reindented_or_body =
98 reindent_multiline(or_body_snippet.into(), true, Some(indent));
100 let suggestion = if scrutinee.span.from_expansion() {
101 // we don't want parenthesis around macro, e.g. `(some_macro!()).unwrap_or(0)`
102 sugg::Sugg::hir_with_macro_callsite(cx, scrutinee, "..")
105 sugg::Sugg::hir(cx, scrutinee, "..").maybe_par()
110 MANUAL_UNWRAP_OR, expr.span,
111 &format!("this pattern reimplements `{}::unwrap_or`", ty_name),
118 Applicability::MachineApplicable,