1 //! lint on inherent implementations
3 use crate::utils::span_lint_and_then;
5 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
6 use rustc::{declare_tool_lint, lint_array};
7 use rustc_data_structures::fx::FxHashMap;
8 use std::default::Default;
11 declare_clippy_lint! {
12 /// **What it does:** Checks for multiple inherent implementations of a struct
14 /// **Why is this bad?** Splitting the implementation of a type makes the code harder to navigate.
16 /// **Known problems:** None.
38 pub MULTIPLE_INHERENT_IMPL,
40 "Multiple inherent impl that could be grouped"
44 impls: FxHashMap<def_id::DefId, (Span, Generics)>,
47 impl Default for Pass {
48 fn default() -> Self {
50 impls: FxHashMap::default(),
55 impl LintPass for Pass {
56 fn get_lints(&self) -> LintArray {
57 lint_array!(MULTIPLE_INHERENT_IMPL)
60 fn name(&self) -> &'static str {
61 "MultipleInherientImpl"
65 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
66 fn check_item(&mut self, _: &LateContext<'a, 'tcx>, item: &'tcx Item) {
67 if let ItemKind::Impl(_, _, _, ref generics, None, _, _) = item.node {
68 // Remember for each inherent implementation encoutered its span and generics
70 .insert(item.hir_id.owner_def_id(), (item.span, generics.clone()));
74 fn check_crate_post(&mut self, cx: &LateContext<'a, 'tcx>, krate: &'tcx Crate) {
75 if let Some(item) = krate.items.values().nth(0) {
76 // Retrieve all inherent implementations from the crate, grouped by type
79 .crate_inherent_impls(item.hir_id.owner_def_id().krate)
83 // Filter out implementations that have generic params (type or lifetime)
84 let mut impl_spans = impls
86 .filter_map(|impl_def| self.impls.get(impl_def))
87 .filter_map(|(span, generics)| if generics.params.len() == 0 { Some(span) } else { None });
88 if let Some(initial_span) = impl_spans.nth(0) {
89 impl_spans.for_each(|additional_span| {
92 MULTIPLE_INHERENT_IMPL,
94 "Multiple implementations of this structure",
96 db.span_note(*initial_span, "First implementation here");