95 lines
3.1 KiB
Rust
95 lines
3.1 KiB
Rust
//! lint on inherent implementations
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use crate::utils::{in_macro, span_lint_and_then};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_hir::{def_id, Crate, Impl, Item, ItemKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::Span;
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declare_clippy_lint! {
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/// **What it does:** Checks for multiple inherent implementations of a struct
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///
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/// **Why is this bad?** Splitting the implementation of a type makes the code harder to navigate.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// struct X;
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/// impl X {
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/// fn one() {}
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/// }
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/// impl X {
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/// fn other() {}
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/// }
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/// ```
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///
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/// Could be written:
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///
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/// ```rust
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/// struct X;
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/// impl X {
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/// fn one() {}
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/// fn other() {}
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/// }
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/// ```
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pub MULTIPLE_INHERENT_IMPL,
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restriction,
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"Multiple inherent impl that could be grouped"
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}
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#[allow(clippy::module_name_repetitions)]
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#[derive(Default)]
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pub struct MultipleInherentImpl {
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impls: FxHashMap<def_id::DefId, Span>,
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}
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impl_lint_pass!(MultipleInherentImpl => [MULTIPLE_INHERENT_IMPL]);
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impl<'tcx> LateLintPass<'tcx> for MultipleInherentImpl {
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fn check_item(&mut self, _: &LateContext<'tcx>, item: &'tcx Item<'_>) {
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if let ItemKind::Impl(Impl {
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ref generics,
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of_trait: None,
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..
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}) = item.kind
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{
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// Remember for each inherent implementation encountered its span and generics
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// but filter out implementations that have generic params (type or lifetime)
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// or are derived from a macro
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if !in_macro(item.span) && generics.params.is_empty() {
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self.impls.insert(item.hir_id.owner.to_def_id(), item.span);
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}
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}
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}
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fn check_crate_post(&mut self, cx: &LateContext<'tcx>, krate: &'tcx Crate<'_>) {
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if let Some(item) = krate.items.values().next() {
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// Retrieve all inherent implementations from the crate, grouped by type
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for impls in cx
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.tcx
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.crate_inherent_impls(item.hir_id.owner.to_def_id().krate)
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.inherent_impls
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.values()
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{
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// Filter out implementations that have generic params (type or lifetime)
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let mut impl_spans = impls.iter().filter_map(|impl_def| self.impls.get(impl_def));
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if let Some(initial_span) = impl_spans.next() {
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impl_spans.for_each(|additional_span| {
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span_lint_and_then(
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cx,
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MULTIPLE_INHERENT_IMPL,
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*additional_span,
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"multiple implementations of this structure",
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|diag| {
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diag.span_note(*initial_span, "first implementation here");
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},
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)
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})
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}
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}
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}
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}
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}
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