| use clippy_utils::diagnostics::{span_lint, span_lint_hir_and_then}; |
| use clippy_utils::path_res; |
| use clippy_utils::ty::implements_trait; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_hir::{Item, ItemKind}; |
| use rustc_hir_analysis::hir_ty_to_ty; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::ty::Visibility; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::sym; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for types named `Error` that implement `Error`. |
| /// |
| /// ### Why is this bad? |
| /// It can become confusing when a codebase has 20 types all named `Error`, requiring either |
| /// aliasing them in the `use` statement or qualifying them like `my_module::Error`. This |
| /// hinders comprehension, as it requires you to memorize every variation of importing `Error` |
| /// used across a codebase. |
| /// |
| /// ### Example |
| /// ```rust,ignore |
| /// #[derive(Debug)] |
| /// pub enum Error { ... } |
| /// |
| /// impl std::fmt::Display for Error { ... } |
| /// |
| /// impl std::error::Error for Error { ... } |
| /// ``` |
| #[clippy::version = "1.72.0"] |
| pub ERROR_IMPL_ERROR, |
| restriction, |
| "exported types named `Error` that implement `Error`" |
| } |
| declare_lint_pass!(ErrorImplError => [ERROR_IMPL_ERROR]); |
| |
| impl<'tcx> LateLintPass<'tcx> for ErrorImplError { |
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) { |
| let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error) else { |
| return; |
| }; |
| |
| match item.kind { |
| ItemKind::TyAlias(ty, _) if implements_trait(cx, hir_ty_to_ty(cx.tcx, ty), error_def_id, &[]) |
| && item.ident.name == sym::Error |
| && is_visible_outside_module(cx, item.owner_id.def_id) => |
| { |
| span_lint( |
| cx, |
| ERROR_IMPL_ERROR, |
| item.ident.span, |
| "exported type alias named `Error` that implements `Error`", |
| ); |
| }, |
| ItemKind::Impl(imp) if let Some(trait_def_id) = imp.of_trait.and_then(|t| t.trait_def_id()) |
| && error_def_id == trait_def_id |
| && let Some(def_id) = path_res(cx, imp.self_ty).opt_def_id().and_then(DefId::as_local) |
| && let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id) |
| && let Some(ident) = cx.tcx.opt_item_ident(def_id.to_def_id()) |
| && ident.name == sym::Error |
| && is_visible_outside_module(cx, def_id) => |
| { |
| span_lint_hir_and_then( |
| cx, |
| ERROR_IMPL_ERROR, |
| hir_id, |
| ident.span, |
| "exported type named `Error` that implements `Error`", |
| |diag| { |
| diag.span_note(item.span, "`Error` was implemented here"); |
| } |
| ); |
| } |
| _ => {}, |
| } |
| } |
| } |
| |
| /// Do not lint private `Error`s, i.e., ones without any `pub` (minus `pub(self)` of course) and |
| /// which aren't reexported |
| fn is_visible_outside_module(cx: &LateContext<'_>, def_id: LocalDefId) -> bool { |
| !matches!( |
| cx.tcx.visibility(def_id), |
| Visibility::Restricted(mod_def_id) if cx.tcx.parent_module_from_def_id(def_id).to_def_id() == mod_def_id |
| ) |
| } |