3 use utils::{match_type, method_chain_args, paths, snippet, span_help_and_lint};
5 /// **What it does:*** Checks for unnecessary `ok()` in if let.
7 /// **Why is this bad?** Calling `ok()` in if let is unnecessary, instead match
10 /// **Known problems:** None.
14 /// for result in iter {
15 /// if let Some(bench) = try!(result).parse().ok() {
23 /// for result in iter {
24 /// if let Ok(bench) = try!(result).parse() {
30 pub IF_LET_SOME_RESULT,
32 "usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
35 #[derive(Copy, Clone)]
38 impl LintPass for Pass {
39 fn get_lints(&self) -> LintArray {
40 lint_array!(IF_LET_SOME_RESULT)
44 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
45 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
46 if_let_chain! {[ //begin checking variables
47 let ExprMatch(ref op, ref body, ref source) = expr.node, //test if expr is a match
48 let MatchSource::IfLetDesugar { .. } = *source, //test if it is an If Let
49 let ExprMethodCall(_, _, ref result_types) = op.node, //check is expr.ok() has type Result<T,E>.ok()
50 let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _) = body[0].pats[0].node, //get operation
51 method_chain_args(op, &["ok"]).is_some() //test to see if using ok() methoduse std::marker::Sized;
54 let is_result_type = match_type(cx, cx.tables.expr_ty(&result_types[0]), &paths::RESULT);
55 let some_expr_string = snippet(cx, y[0].span, "");
56 if print::to_string(print::NO_ANN, |s| s.print_path(x, false)) == "Some" && is_result_type {
57 span_help_and_lint(cx, IF_LET_SOME_RESULT, expr.span,
58 "Matching on `Some` with `ok()` is redundant",
59 &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string));