| 1 | use clippy_utils::diagnostics::{span_lint, span_lint_hir_and_then}; |
| 2 | use clippy_utils::path_res; |
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| 3 | use clippy_utils::ty::implements_trait; |
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| 4 | use rustc_hir::def_id::{DefId, LocalDefId}; |
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| 5 | use rustc_hir::{Item, ItemKind}; |
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| 6 | use rustc_lint::{LateContext, LateLintPass}; |
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| 7 | use rustc_middle::ty::Visibility; |
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| 8 | use rustc_session::declare_lint_pass; |
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| 9 | use rustc_span::sym; |
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| 10 | |
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| 11 | declare_clippy_lint! { |
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| 12 | /// ### What it does |
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| 13 | /// Checks for types named `Error` that implement `Error`. |
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| 14 | /// |
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| 15 | /// ### Why restrict this? |
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| 16 | /// It can become confusing when a codebase has 20 types all named `Error`, requiring either |
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| 17 | /// aliasing them in the `use` statement or qualifying them like `my_module::Error`. This |
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| 18 | /// hinders comprehension, as it requires you to memorize every variation of importing `Error` |
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| 19 | /// used across a codebase. |
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| 20 | /// |
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| 21 | /// ### Example |
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| 22 | /// ```rust,ignore |
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| 23 | /// #[derive(Debug)] |
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| 24 | /// pub enum Error { ... } |
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| 25 | /// |
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| 26 | /// impl std::fmt::Display for Error { ... } |
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| 27 | /// |
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| 28 | /// impl std::error::Error for Error { ... } |
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| 29 | /// ``` |
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| 30 | #[clippy::version = "1.73.0" ] |
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| 31 | pub ERROR_IMPL_ERROR, |
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| 32 | restriction, |
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| 33 | "exported types named `Error` that implement `Error`" |
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| 34 | } |
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| 35 | declare_lint_pass!(ErrorImplError => [ERROR_IMPL_ERROR]); |
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| 36 | |
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| 37 | impl<'tcx> LateLintPass<'tcx> for ErrorImplError { |
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| 38 | fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) { |
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| 39 | match item.kind { |
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| 40 | ItemKind::TyAlias(ident, ..) |
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| 41 | if ident.name == sym::Error |
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| 42 | && is_visible_outside_module(cx, item.owner_id.def_id) |
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| 43 | && let ty = cx.tcx.type_of(item.owner_id).instantiate_identity() |
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| 44 | && let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error) |
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| 45 | && implements_trait(cx, ty, error_def_id, &[]) => |
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| 46 | { |
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| 47 | span_lint( |
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| 48 | cx, |
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| 49 | ERROR_IMPL_ERROR, |
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| 50 | ident.span, |
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| 51 | "exported type alias named `Error` that implements `Error`" , |
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| 52 | ); |
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| 53 | }, |
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| 54 | ItemKind::Impl(imp) |
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| 55 | if let Some(trait_def_id) = imp.of_trait.and_then(|t| t.trait_def_id()) |
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| 56 | && let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error) |
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| 57 | && error_def_id == trait_def_id |
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| 58 | && let Some(def_id) = path_res(cx, imp.self_ty).opt_def_id().and_then(DefId::as_local) |
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| 59 | && let Some(ident) = cx.tcx.opt_item_ident(def_id.to_def_id()) |
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| 60 | && ident.name == sym::Error |
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| 61 | && is_visible_outside_module(cx, def_id) => |
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| 62 | { |
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| 63 | span_lint_hir_and_then( |
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| 64 | cx, |
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| 65 | ERROR_IMPL_ERROR, |
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| 66 | cx.tcx.local_def_id_to_hir_id(def_id), |
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| 67 | ident.span, |
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| 68 | "exported type named `Error` that implements `Error`" , |
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| 69 | |diag| { |
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| 70 | diag.span_note(item.span, "`Error` was implemented here" ); |
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| 71 | }, |
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| 72 | ); |
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| 73 | }, |
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| 74 | _ => {}, |
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| 75 | } |
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| 76 | } |
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| 77 | } |
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| 78 | |
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| 79 | /// Do not lint private `Error`s, i.e., ones without any `pub` (minus `pub(self)` of course) and |
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| 80 | /// which aren't reexported |
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| 81 | fn is_visible_outside_module(cx: &LateContext<'_>, def_id: LocalDefId) -> bool { |
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| 82 | !matches!( |
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| 83 | cx.tcx.visibility(def_id), |
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| 84 | 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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| 85 | ) |
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| 86 | } |
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| 87 | |
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