| use crate::utils::{match_type, method_chain_args, paths, snippet, span_help_and_lint}; |
| use if_chain::if_chain; |
| use rustc::hir::*; |
| use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; |
| use rustc::{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 result in iter { |
| /// if let Some(bench) = try!(result).parse().ok() { |
| /// vec.push(bench) |
| /// } |
| /// } |
| /// ``` |
| /// Could be written: |
| /// |
| /// ```ignore |
| /// for result in iter { |
| /// if let Ok(bench) = try!(result).parse() { |
| /// vec.push(bench) |
| /// } |
| /// } |
| /// ``` |
| 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<'a, 'tcx> LateLintPass<'a, 'tcx> for OkIfLet { |
| fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) { |
| if_chain! { //begin checking variables |
| if let ExprKind::Match(ref op, ref body, ref 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(_, _, 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; |
| |
| then { |
| let is_result_type = match_type(cx, cx.tables.expr_ty(&result_types[0]), &paths::RESULT); |
| let some_expr_string = snippet(cx, y[0].span, ""); |
| if print::to_string(print::NO_ANN, |s| s.print_path(x, false)) == "Some" && is_result_type { |
| span_help_and_lint(cx, IF_LET_SOME_RESULT, expr.span, |
| "Matching on `Some` with `ok()` is redundant", |
| &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string)); |
| } |
| } |
| } |
| } |
| } |