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use clippy_utils::diagnostics::span_lint_hir_and_then;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::{HirId, Impl, ItemKind, Node, Path, QPath, TraitRef, TyKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::AssocKind;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::Symbol;
use rustc_span::Span;
use std::collections::{BTreeMap, BTreeSet};
declare_clippy_lint! {
/// ### What it does
/// It lints if a struct has two methods with the same name:
/// one from a trait, another not from trait.
///
/// ### Why is this bad?
/// Confusing.
///
/// ### Example
/// ```rust
/// trait T {
/// fn foo(&self) {}
/// }
///
/// struct S;
///
/// impl T for S {
/// fn foo(&self) {}
/// }
///
/// impl S {
/// fn foo(&self) {}
/// }
/// ```
#[clippy::version = "1.57.0"]
pub SAME_NAME_METHOD,
restriction,
"two method with same name"
}
declare_lint_pass!(SameNameMethod => [SAME_NAME_METHOD]);
struct ExistingName {
impl_methods: BTreeMap<Symbol, (Span, HirId)>,
trait_methods: BTreeMap<Symbol, Vec<Span>>,
}
impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
#[expect(clippy::too_many_lines)]
fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
let mut map = FxHashMap::<Res, ExistingName>::default();
for id in cx.tcx.hir().items() {
if matches!(cx.tcx.def_kind(id.owner_id), DefKind::Impl { .. })
&& let item = cx.tcx.hir().item(id)
&& let ItemKind::Impl(Impl {
items,
of_trait,
self_ty,
..
}) = &item.kind
&& let TyKind::Path(QPath::Resolved(_, Path { res, .. })) = self_ty.kind
{
if !map.contains_key(res) {
map.insert(
*res,
ExistingName {
impl_methods: BTreeMap::new(),
trait_methods: BTreeMap::new(),
},
);
}
let existing_name = map.get_mut(res).unwrap();
match of_trait {
Some(trait_ref) => {
let mut methods_in_trait: BTreeSet<Symbol> = if_chain! {
if let Some(Node::TraitRef(TraitRef { path, .. })) =
cx.tcx.hir().find(trait_ref.hir_ref_id);
if let Res::Def(DefKind::Trait, did) = path.res;
then{
// FIXME: if
// `rustc_middle::ty::assoc::AssocItems::items` is public,
// we can iterate its keys instead of `in_definition_order`,
// which's more efficient
cx.tcx
.associated_items(did)
.in_definition_order()
.filter(|assoc_item| {
matches!(assoc_item.kind, AssocKind::Fn)
})
.map(|assoc_item| assoc_item.name)
.collect()
}else{
BTreeSet::new()
}
};
let mut check_trait_method = |method_name: Symbol, trait_method_span: Span| {
if let Some((impl_span, hir_id)) = existing_name.impl_methods.get(&method_name) {
span_lint_hir_and_then(
cx,
SAME_NAME_METHOD,
*hir_id,
*impl_span,
"method's name is the same as an existing method in a trait",
|diag| {
diag.span_note(
trait_method_span,
format!("existing `{method_name}` defined here"),
);
},
);
}
if let Some(v) = existing_name.trait_methods.get_mut(&method_name) {
v.push(trait_method_span);
} else {
existing_name.trait_methods.insert(method_name, vec![trait_method_span]);
}
};
for impl_item_ref in (*items).iter().filter(|impl_item_ref| {
matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. })
}) {
let method_name = impl_item_ref.ident.name;
methods_in_trait.remove(&method_name);
check_trait_method(method_name, impl_item_ref.span);
}
for method_name in methods_in_trait {
check_trait_method(method_name, item.span);
}
},
None => {
for impl_item_ref in (*items).iter().filter(|impl_item_ref| {
matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. })
}) {
let method_name = impl_item_ref.ident.name;
let impl_span = impl_item_ref.span;
let hir_id = impl_item_ref.id.hir_id();
if let Some(trait_spans) = existing_name.trait_methods.get(&method_name) {
span_lint_hir_and_then(
cx,
SAME_NAME_METHOD,
hir_id,
impl_span,
"method's name is the same as an existing method in a trait",
|diag| {
// TODO should we `span_note` on every trait?
// iterate on trait_spans?
diag.span_note(
trait_spans[0],
format!("existing `{method_name}` defined here"),
);
},
);
}
existing_name.impl_methods.insert(method_name, (impl_span, hir_id));
}
},
}
}
}
}
}
|
