1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::higher;
3 use clippy_utils::method_chain_args;
4 use clippy_utils::source::snippet_with_applicability;
5 use clippy_utils::ty::is_type_diagnostic_item;
6 use if_chain::if_chain;
7 use rustc_errors::Applicability;
8 use rustc_hir::{Expr, ExprKind, PatKind, QPath};
9 use rustc_lint::{LateContext, LateLintPass};
10 use rustc_session::{declare_lint_pass, declare_tool_lint};
13 declare_clippy_lint! {
15 /// Checks for unnecessary `ok()` in `while let`.
17 /// ### Why is this bad?
18 /// Calling `ok()` in `while let` is unnecessary, instead match
23 /// while let Some(value) = iter.next().ok() {
27 /// if let Some(valie) = iter.next().ok() {
33 /// while let Ok(value) = iter.next() {
37 /// if let Ok(value) = iter.next() {
43 "usage of `ok()` in `let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
46 declare_lint_pass!(MatchResultOk => [MATCH_RESULT_OK]);
48 impl<'tcx> LateLintPass<'tcx> for MatchResultOk {
49 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
50 let (let_pat, let_expr, ifwhile) =
51 if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr) {
52 (let_pat, let_expr, "if")
53 } else if let Some(higher::WhileLet { let_pat, let_expr, .. }) = higher::WhileLet::hir(expr) {
54 (let_pat, let_expr, "while")
60 if let ExprKind::MethodCall(_, ok_span, [ref result_types_0, ..], _) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
61 if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _) = let_pat.kind; //get operation
62 if method_chain_args(let_expr, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
63 if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(result_types_0), sym::Result);
64 if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";
68 let mut applicability = Applicability::MachineApplicable;
69 let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
70 let trimmed_ok = snippet_with_applicability(cx, let_expr.span.until(ok_span), "", &mut applicability);
75 trimmed_ok.trim().trim_end_matches('.'),
80 expr.span.with_hi(let_expr.span.hi()),
81 "matching on `Some` with `ok()` is redundant",
82 &format!("consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),