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|
use clippy_utils::diagnostics::{span_lint_and_then, span_lint_hir_and_then};
use clippy_utils::is_doc_hidden;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::source::snippet_opt;
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_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: Msrv,
}
impl ManualNonExhaustiveStruct {
#[must_use]
pub fn new(msrv: Msrv) -> Self {
Self { msrv }
}
}
impl_lint_pass!(ManualNonExhaustiveStruct => [MANUAL_NON_EXHAUSTIVE]);
#[expect(clippy::module_name_repetitions)]
pub struct ManualNonExhaustiveEnum {
msrv: Msrv,
constructed_enum_variants: FxHashSet<(DefId, DefId)>,
potential_enums: Vec<(LocalDefId, LocalDefId, Span, Span)>,
}
impl ManualNonExhaustiveEnum {
#[must_use]
pub fn new(msrv: Msrv) -> 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 !self.msrv.meets(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 !self.msrv.meets(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.hir_id);
(matches!(v.data, hir::VariantData::Unit(..))
&& v.ident.as_str().starts_with('_')
&& is_doc_hidden(cx.tcx.hir().attrs(v.hir_id)))
.then_some((id, v.span))
});
if let Some((id, span)) = iter.next()
&& iter.next().is_none()
{
self.potential_enums.push((item.owner_id.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);
}
|
