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 if let.
17 /// ### Why is this bad?
18 /// Calling `ok()` in if let is unnecessary, instead match
24 /// if let Some(value) = i.parse().ok() {
33 /// if let Ok(value) = i.parse() {
38 pub IF_LET_SOME_RESULT,
40 "usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
43 declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]);
45 impl<'tcx> LateLintPass<'tcx> for OkIfLet {
46 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
47 if_chain! { //begin checking variables
48 if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr);
49 if let ExprKind::MethodCall(_, ok_span, [ref result_types_0, ..], _) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
50 if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _) = let_pat.kind; //get operation
51 if method_chain_args(let_expr, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
52 if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(result_types_0), sym::result_type);
53 if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";
56 let mut applicability = Applicability::MachineApplicable;
57 let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
58 let trimmed_ok = snippet_with_applicability(cx, let_expr.span.until(ok_span), "", &mut applicability);
62 trimmed_ok.trim().trim_end_matches('.'),
67 expr.span.with_hi(let_expr.span.hi()),
68 "matching on `Some` with `ok()` is redundant",
69 &format!("consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),