2 is_type_diagnostic_item, match_trait_method, paths, snippet, snippet_with_applicability, span_lint_and_help,
3 span_lint_and_sugg, strip_pat_refs,
5 use if_chain::if_chain;
6 use rustc_errors::Applicability;
8 use rustc_hir::PatKind;
9 use rustc_lint::LateContext;
11 use rustc_span::source_map::Span;
12 use rustc_span::symbol::sym;
14 use super::SEARCH_IS_SOME;
16 /// lint searching an Iterator followed by `is_some()`
17 /// or calling `find()` on a string followed by `is_some()`
18 pub(super) fn check<'tcx>(
19 cx: &LateContext<'tcx>,
20 expr: &'tcx hir::Expr<'_>,
22 search_args: &'tcx [hir::Expr<'_>],
23 is_some_args: &'tcx [hir::Expr<'_>],
26 // lint if caller of search is an Iterator
27 if match_trait_method(cx, &is_some_args[0], &paths::ITERATOR) {
29 "called `is_some()` after searching an `Iterator` with `{}`",
32 let hint = "this is more succinctly expressed by calling `any()`";
33 let search_snippet = snippet(cx, search_args[1].span, "..");
34 if search_snippet.lines().count() <= 1 {
35 // suggest `any(|x| ..)` instead of `any(|&x| ..)` for `find(|&x| ..).is_some()`
36 // suggest `any(|..| *..)` instead of `any(|..| **..)` for `find(|..| **..).is_some()`
37 let any_search_snippet = if_chain! {
38 if search_method == "find";
39 if let hir::ExprKind::Closure(_, _, body_id, ..) = search_args[1].kind;
40 let closure_body = cx.tcx.hir().body(body_id);
41 if let Some(closure_arg) = closure_body.params.get(0);
43 if let hir::PatKind::Ref(..) = closure_arg.pat.kind {
44 Some(search_snippet.replacen('&', "", 1))
45 } else if let PatKind::Binding(_, _, ident, _) = strip_pat_refs(&closure_arg.pat).kind {
46 let name = &*ident.name.as_str();
47 Some(search_snippet.replace(&format!("*{}", name), name))
55 // add note if not multi-line
59 method_span.with_hi(expr.span.hi()),
61 "use `any()` instead",
64 any_search_snippet.as_ref().map_or(&*search_snippet, String::as_str)
66 Applicability::MachineApplicable,
69 span_lint_and_help(cx, SEARCH_IS_SOME, expr.span, &msg, None, hint);
72 // lint if `find()` is called by `String` or `&str`
73 else if search_method == "find" {
74 let is_string_or_str_slice = |e| {
75 let self_ty = cx.typeck_results().expr_ty(e).peel_refs();
76 if is_type_diagnostic_item(cx, self_ty, sym::string_type) {
79 *self_ty.kind() == ty::Str
83 if is_string_or_str_slice(&search_args[0]);
84 if is_string_or_str_slice(&search_args[1]);
86 let msg = "called `is_some()` after calling `find()` on a string";
87 let mut applicability = Applicability::MachineApplicable;
88 let find_arg = snippet_with_applicability(cx, search_args[1].span, "..", &mut applicability);
92 method_span.with_hi(expr.span.hi()),
94 "use `contains()` instead",
95 format!("contains({})", find_arg),