| use crate::utils::{is_type_diagnostic_item, method_chain_args, snippet_with_applicability, span_lint_and_sugg}; |
| use if_chain::if_chain; |
| use rustc_errors::Applicability; |
| use rustc_hir::{Expr, ExprKind, MatchSource, PatKind, QPath}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| |
| declare_clippy_lint! { |
| /// **What it does:*** Checks for unnecessary `ok()` in if let. |
| /// |
| /// **Why is this bad?** Calling `ok()` in if let is unnecessary, instead match |
| /// on `Ok(pat)` |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```ignore |
| /// for i in iter { |
| /// if let Some(value) = i.parse().ok() { |
| /// vec.push(value) |
| /// } |
| /// } |
| /// ``` |
| /// Could be written: |
| /// |
| /// ```ignore |
| /// for i in iter { |
| /// if let Ok(value) = i.parse() { |
| /// vec.push(value) |
| /// } |
| /// } |
| /// ``` |
| pub IF_LET_SOME_RESULT, |
| style, |
| "usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead" |
| } |
| |
| declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]); |
| |
| impl<'tcx> LateLintPass<'tcx> for OkIfLet { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if_chain! { //begin checking variables |
| if let ExprKind::Match(ref op, ref body, source) = expr.kind; //test if expr is a match |
| if let MatchSource::IfLetDesugar { .. } = source; //test if it is an If Let |
| if let ExprKind::MethodCall(_, ok_span, ref result_types, _) = op.kind; //check is expr.ok() has type Result<T,E>.ok(, _) |
| if let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _) = body[0].pat.kind; //get operation |
| if method_chain_args(op, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized; |
| if is_type_diagnostic_item(cx, cx.tables().expr_ty(&result_types[0]), sym!(result_type)); |
| 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, op.span.until(ok_span), "", &mut applicability); |
| let sugg = format!( |
| "if let Ok({}) = {}", |
| some_expr_string, |
| trimmed_ok.trim().trim_end_matches('.'), |
| ); |
| span_lint_and_sugg( |
| cx, |
| IF_LET_SOME_RESULT, |
| expr.span.with_hi(op.span.hi()), |
| "Matching on `Some` with `ok()` is redundant", |
| &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string), |
| sugg, |
| applicability, |
| ); |
| } |
| } |
| } |
| } |