103 lines
3.0 KiB
Rust
103 lines
3.0 KiB
Rust
//! lint on inherent implementations
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use rustc::hir::*;
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use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use rustc::{declare_tool_lint, lint_array};
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use std::collections::HashMap;
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use std::default::Default;
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use syntax_pos::Span;
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use crate::utils::span_lint_and_then;
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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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declare_clippy_lint! {
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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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pub struct Pass {
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impls: HashMap<def_id::DefId, (Span, Generics)>,
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}
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impl Default for Pass {
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fn default() -> Self {
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Pass { impls: HashMap::new() }
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}
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}
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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lint_array!(MULTIPLE_INHERENT_IMPL)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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fn check_item(&mut self, _: &LateContext<'a, 'tcx>, item: &'tcx Item) {
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if let ItemKind::Impl(_, _, _, ref generics, None, _, _) = item.node {
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// Remember for each inherent implementation encoutered its span and generics
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self.impls
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.insert(item.hir_id.owner_def_id(), (item.span, generics.clone()));
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}
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}
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fn check_crate_post(&mut self, cx: &LateContext<'a, 'tcx>, krate: &'tcx Crate) {
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if let Some(item) = krate.items.values().nth(0) {
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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_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
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.iter()
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.filter_map(|impl_def| self.impls.get(impl_def))
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.filter(|(_, generics)| generics.params.len() == 0)
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.map(|(span, _)| span);
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if let Some(initial_span) = impl_spans.nth(0) {
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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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|db| {
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db.span_note(
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*initial_span,
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"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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}
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