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Diffstat (limited to '')
| -rw-r--r-- | src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs new file mode 100644 index 000000000..2b04475c7 --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/manual_non_exhaustive.rs @@ -0,0 +1,221 @@ +use clippy_utils::diagnostics::{span_lint_and_then, span_lint_hir_and_then}; +use clippy_utils::source::snippet_opt; +use clippy_utils::{is_doc_hidden, meets_msrv, msrvs}; +use rustc_ast::ast::{self, VisibilityKind}; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::Applicability; +use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res}; +use rustc_hir::{self as hir, Expr, ExprKind, QPath}; +use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext}; +use rustc_middle::ty::DefIdTree; +use rustc_semver::RustcVersion; +use rustc_session::{declare_tool_lint, impl_lint_pass}; +use rustc_span::def_id::{DefId, LocalDefId}; +use rustc_span::{sym, Span}; + +declare_clippy_lint! { + /// ### What it does + /// Checks for manual implementations of the non-exhaustive pattern. + /// + /// ### Why is this bad? + /// Using the #[non_exhaustive] attribute expresses better the intent + /// and allows possible optimizations when applied to enums. + /// + /// ### Example + /// ```rust + /// struct S { + /// pub a: i32, + /// pub b: i32, + /// _c: (), + /// } + /// + /// enum E { + /// A, + /// B, + /// #[doc(hidden)] + /// _C, + /// } + /// + /// struct T(pub i32, pub i32, ()); + /// ``` + /// Use instead: + /// ```rust + /// #[non_exhaustive] + /// struct S { + /// pub a: i32, + /// pub b: i32, + /// } + /// + /// #[non_exhaustive] + /// enum E { + /// A, + /// B, + /// } + /// + /// #[non_exhaustive] + /// struct T(pub i32, pub i32); + /// ``` + #[clippy::version = "1.45.0"] + pub MANUAL_NON_EXHAUSTIVE, + style, + "manual implementations of the non-exhaustive pattern can be simplified using #[non_exhaustive]" +} + +#[expect(clippy::module_name_repetitions)] +pub struct ManualNonExhaustiveStruct { + msrv: Option<RustcVersion>, +} + +impl ManualNonExhaustiveStruct { + #[must_use] + pub fn new(msrv: Option<RustcVersion>) -> Self { + Self { msrv } + } +} + +impl_lint_pass!(ManualNonExhaustiveStruct => [MANUAL_NON_EXHAUSTIVE]); + +#[expect(clippy::module_name_repetitions)] +pub struct ManualNonExhaustiveEnum { + msrv: Option<RustcVersion>, + constructed_enum_variants: FxHashSet<(DefId, DefId)>, + potential_enums: Vec<(LocalDefId, LocalDefId, Span, Span)>, +} + +impl ManualNonExhaustiveEnum { + #[must_use] + pub fn new(msrv: Option<RustcVersion>) -> Self { + Self { + msrv, + constructed_enum_variants: FxHashSet::default(), + potential_enums: Vec::new(), + } + } +} + +impl_lint_pass!(ManualNonExhaustiveEnum => [MANUAL_NON_EXHAUSTIVE]); + +impl EarlyLintPass for ManualNonExhaustiveStruct { + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) { + if !meets_msrv(self.msrv, msrvs::NON_EXHAUSTIVE) { + return; + } + + if let ast::ItemKind::Struct(variant_data, _) = &item.kind { + let (fields, delimiter) = match variant_data { + ast::VariantData::Struct(fields, _) => (&**fields, '{'), + ast::VariantData::Tuple(fields, _) => (&**fields, '('), + ast::VariantData::Unit(_) => return, + }; + if fields.len() <= 1 { + return; + } + let mut iter = fields.iter().filter_map(|f| match f.vis.kind { + VisibilityKind::Public => None, + VisibilityKind::Inherited => Some(Ok(f)), + VisibilityKind::Restricted { .. } => Some(Err(())), + }); + if let Some(Ok(field)) = iter.next() + && iter.next().is_none() + && field.ty.kind.is_unit() + && field.ident.map_or(true, |name| name.as_str().starts_with('_')) + { + span_lint_and_then( + cx, + MANUAL_NON_EXHAUSTIVE, + item.span, + "this seems like a manual implementation of the non-exhaustive pattern", + |diag| { + if !item.attrs.iter().any(|attr| attr.has_name(sym::non_exhaustive)) + && let header_span = cx.sess().source_map().span_until_char(item.span, delimiter) + && let Some(snippet) = snippet_opt(cx, header_span) + { + diag.span_suggestion( + header_span, + "add the attribute", + format!("#[non_exhaustive] {}", snippet), + Applicability::Unspecified, + ); + } + diag.span_help(field.span, "remove this field"); + } + ); + } + } + } + + extract_msrv_attr!(EarlyContext); +} + +impl<'tcx> LateLintPass<'tcx> for ManualNonExhaustiveEnum { + fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) { + if !meets_msrv(self.msrv, msrvs::NON_EXHAUSTIVE) { + return; + } + + if let hir::ItemKind::Enum(def, _) = &item.kind + && def.variants.len() > 1 + { + let mut iter = def.variants.iter().filter_map(|v| { + let id = cx.tcx.hir().local_def_id(v.id); + (matches!(v.data, hir::VariantData::Unit(_)) + && v.ident.as_str().starts_with('_') + && is_doc_hidden(cx.tcx.hir().attrs(v.id))) + .then_some((id, v.span)) + }); + if let Some((id, span)) = iter.next() + && iter.next().is_none() + { + self.potential_enums.push((item.def_id, id, item.span, span)); + } + } + } + + fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) { + if let ExprKind::Path(QPath::Resolved(None, p)) = &e.kind + && let [.., name] = p.segments + && let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Const), id) = p.res + && name.ident.as_str().starts_with('_') + { + let variant_id = cx.tcx.parent(id); + let enum_id = cx.tcx.parent(variant_id); + + self.constructed_enum_variants.insert((enum_id, variant_id)); + } + } + + fn check_crate_post(&mut self, cx: &LateContext<'tcx>) { + for &(enum_id, _, enum_span, variant_span) in + self.potential_enums.iter().filter(|&&(enum_id, variant_id, _, _)| { + !self + .constructed_enum_variants + .contains(&(enum_id.to_def_id(), variant_id.to_def_id())) + }) + { + let hir_id = cx.tcx.hir().local_def_id_to_hir_id(enum_id); + span_lint_hir_and_then( + cx, + MANUAL_NON_EXHAUSTIVE, + hir_id, + enum_span, + "this seems like a manual implementation of the non-exhaustive pattern", + |diag| { + if !cx.tcx.adt_def(enum_id).is_variant_list_non_exhaustive() + && let header_span = cx.sess().source_map().span_until_char(enum_span, '{') + && let Some(snippet) = snippet_opt(cx, header_span) + { + diag.span_suggestion( + header_span, + "add the attribute", + format!("#[non_exhaustive] {}", snippet), + Applicability::Unspecified, + ); + } + diag.span_help(variant_span, "remove this variant"); + }, + ); + } + } + + extract_msrv_attr!(LateContext); +} |