| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::higher; |
| use clippy_utils::method_chain_args; |
| use clippy_utils::source::snippet_with_applicability; |
| use clippy_utils::ty::is_type_diagnostic_item; |
| use if_chain::if_chain; |
| use rustc_errors::Applicability; |
| use rustc_hir::{Expr, ExprKind, PatKind, QPath}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::sym; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for unnecessary `ok()` in `while let`. |
| /// |
| /// ### Why is this bad? |
| /// Calling `ok()` in `while let` is unnecessary, instead match |
| /// on `Ok(pat)` |
| /// |
| /// ### Example |
| /// ```ignore |
| /// while let Some(value) = iter.next().ok() { |
| /// vec.push(value) |
| /// } |
| /// |
| /// if let Some(value) = iter.next().ok() { |
| /// vec.push(value) |
| /// } |
| /// ``` |
| /// Use instead: |
| /// ```ignore |
| /// while let Ok(value) = iter.next() { |
| /// vec.push(value) |
| /// } |
| /// |
| /// if let Ok(value) = iter.next() { |
| /// vec.push(value) |
| /// } |
| /// ``` |
| #[clippy::version = "1.57.0"] |
| pub MATCH_RESULT_OK, |
| style, |
| "usage of `ok()` in `let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead" |
| } |
| |
| declare_lint_pass!(MatchResultOk => [MATCH_RESULT_OK]); |
| |
| impl<'tcx> LateLintPass<'tcx> for MatchResultOk { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| let (let_pat, let_expr, ifwhile) = |
| if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr) { |
| (let_pat, let_expr, "if") |
| } else if let Some(higher::WhileLet { let_pat, let_expr, .. }) = higher::WhileLet::hir(expr) { |
| (let_pat, let_expr, "while") |
| } else { |
| return; |
| }; |
| |
| if_chain! { |
| if let ExprKind::MethodCall(ok_path, result_types_0, ..) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _) |
| if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _) = let_pat.kind; //get operation |
| if method_chain_args(let_expr, &["ok"]).is_some(); //test to see if using ok() method use std::marker::Sized; |
| if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(result_types_0), sym::Result); |
| if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some"; |
| |
| then { |
| |
| let mut applicability = Applicability::MachineApplicable; |
| let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability); |
| let trimmed_ok = snippet_with_applicability(cx, let_expr.span.until(ok_path.ident.span), "", &mut applicability); |
| let sugg = format!( |
| "{ifwhile} let Ok({some_expr_string}) = {}", |
| trimmed_ok.trim().trim_end_matches('.'), |
| ); |
| span_lint_and_sugg( |
| cx, |
| MATCH_RESULT_OK, |
| expr.span.with_hi(let_expr.span.hi()), |
| "matching on `Some` with `ok()` is redundant", |
| &format!("consider matching on `Ok({some_expr_string})` and removing the call to `ok` instead"), |
| sugg, |
| applicability, |
| ); |
| } |
| } |
| } |
| } |