90 lines
3.4 KiB
Rust
90 lines
3.4 KiB
Rust
use clippy_utils::diagnostics::{span_lint, span_lint_hir_and_then};
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use clippy_utils::path_res;
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use clippy_utils::ty::implements_trait;
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use rustc_hir::def_id::{DefId, LocalDefId};
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use rustc_hir::{Item, ItemKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::Visibility;
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use rustc_session::declare_lint_pass;
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for types named `Error` that implement `Error`.
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///
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/// ### Why is this bad?
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/// It can become confusing when a codebase has 20 types all named `Error`, requiring either
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/// aliasing them in the `use` statement or qualifying them like `my_module::Error`. This
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/// hinders comprehension, as it requires you to memorize every variation of importing `Error`
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/// used across a codebase.
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///
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/// ### Example
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/// ```rust,ignore
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/// #[derive(Debug)]
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/// pub enum Error { ... }
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///
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/// impl std::fmt::Display for Error { ... }
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///
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/// impl std::error::Error for Error { ... }
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/// ```
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#[clippy::version = "1.73.0"]
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pub ERROR_IMPL_ERROR,
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restriction,
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"exported types named `Error` that implement `Error`"
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}
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declare_lint_pass!(ErrorImplError => [ERROR_IMPL_ERROR]);
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impl<'tcx> LateLintPass<'tcx> for ErrorImplError {
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fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
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let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error) else {
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return;
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};
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match item.kind {
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ItemKind::TyAlias(..)
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if item.ident.name == sym::Error
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&& is_visible_outside_module(cx, item.owner_id.def_id)
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&& let ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
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&& implements_trait(cx, ty, error_def_id, &[]) =>
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{
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span_lint(
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cx,
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ERROR_IMPL_ERROR,
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item.ident.span,
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"exported type alias named `Error` that implements `Error`",
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);
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},
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ItemKind::Impl(imp)
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if let Some(trait_def_id) = imp.of_trait.and_then(|t| t.trait_def_id())
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&& error_def_id == trait_def_id
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&& let Some(def_id) = path_res(cx, imp.self_ty).opt_def_id().and_then(DefId::as_local)
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&& let hir_id = cx.tcx.local_def_id_to_hir_id(def_id)
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&& let Some(ident) = cx.tcx.opt_item_ident(def_id.to_def_id())
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&& ident.name == sym::Error
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&& is_visible_outside_module(cx, def_id) =>
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{
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span_lint_hir_and_then(
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cx,
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ERROR_IMPL_ERROR,
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hir_id,
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ident.span,
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"exported type named `Error` that implements `Error`",
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|diag| {
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diag.span_note(item.span, "`Error` was implemented 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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/// Do not lint private `Error`s, i.e., ones without any `pub` (minus `pub(self)` of course) and
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/// which aren't reexported
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fn is_visible_outside_module(cx: &LateContext<'_>, def_id: LocalDefId) -> bool {
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!matches!(
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cx.tcx.visibility(def_id),
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Visibility::Restricted(mod_def_id) if cx.tcx.parent_module_from_def_id(def_id).to_def_id() == mod_def_id
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)
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}
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