1 //! lint on inherent implementations
4 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
5 use rustc::{declare_tool_lint, lint_array};
6 use rustc_data_structures::fx::FxHashMap;
7 use std::default::Default;
9 use crate::utils::span_lint_and_then;
11 /// **What it does:** Checks for multiple inherent implementations of a struct
13 /// **Why is this bad?** Splitting the implementation of a type makes the code harder to navigate.
15 /// **Known problems:** None.
37 declare_clippy_lint! {
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 {
49 Pass { impls: FxHashMap::default() }
53 impl LintPass for Pass {
54 fn get_lints(&self) -> LintArray {
55 lint_array!(MULTIPLE_INHERENT_IMPL)
59 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
60 fn check_item(&mut self, _: &LateContext<'a, 'tcx>, item: &'tcx Item) {
61 if let ItemKind::Impl(_, _, _, ref generics, None, _, _) = item.node {
62 // Remember for each inherent implementation encoutered its span and generics
64 .insert(item.hir_id.owner_def_id(), (item.span, generics.clone()));
68 fn check_crate_post(&mut self, cx: &LateContext<'a, 'tcx>, krate: &'tcx Crate) {
69 if let Some(item) = krate.items.values().nth(0) {
70 // Retrieve all inherent implementations from the crate, grouped by type
73 .crate_inherent_impls(item.hir_id.owner_def_id().krate)
77 // Filter out implementations that have generic params (type or lifetime)
78 let mut impl_spans = impls
80 .filter_map(|impl_def| self.impls.get(impl_def))
81 .filter_map(|(span, generics)| if generics.params.len() == 0 {
86 if let Some(initial_span) = impl_spans.nth(0) {
87 impl_spans.for_each(|additional_span| {
90 MULTIPLE_INHERENT_IMPL,
92 "Multiple implementations of this structure",
96 "First implementation here",