1 use clippy_utils::diagnostics::span_lint;
2 use clippy_utils::{get_trait_def_id, paths};
3 use rustc_hir::{Impl, Item, ItemKind};
4 use rustc_lint::{LateContext, LateLintPass};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
8 /// **What it does:** Checks for mis-uses of the serde API.
10 /// **Why is this bad?** Serde is very finnicky about how its API should be
11 /// used, but the type system can't be used to enforce it (yet?).
13 /// **Known problems:** None.
15 /// **Example:** Implementing `Visitor::visit_string` but not
16 /// `Visitor::visit_str`.
19 "various things that will negatively affect your serde experience"
22 declare_lint_pass!(SerdeApi => [SERDE_API_MISUSE]);
24 impl<'tcx> LateLintPass<'tcx> for SerdeApi {
25 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
26 if let ItemKind::Impl(Impl {
27 of_trait: Some(ref trait_ref),
32 let did = trait_ref.path.res.def_id();
33 if let Some(visit_did) = get_trait_def_id(cx, &paths::SERDE_DE_VISITOR) {
35 let mut seen_str = None;
36 let mut seen_string = None;
38 match &*item.ident.as_str() {
39 "visit_str" => seen_str = Some(item.span),
40 "visit_string" => seen_string = Some(item.span),
44 if let Some(span) = seen_string {
45 if seen_str.is_none() {
50 "you should not implement `visit_string` without also implementing `visit_str`",