+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::trait_ref_of_method;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_hir::def::{DefKind, Res};
+use rustc_hir::intravisit::nested_filter::{self as hir_nested_filter, NestedFilter};
use rustc_hir::intravisit::{
- walk_fn_decl, walk_generic_param, walk_generics, walk_param_bound, walk_ty, NestedVisitorMap, Visitor,
+ walk_fn_decl, walk_generic_param, walk_generics, walk_impl_item_ref, walk_item, walk_param_bound,
+ walk_poly_trait_ref, walk_trait_ref, walk_ty, Visitor,
};
use rustc_hir::FnRetTy::Return;
use rustc_hir::{
- BodyId, FnDecl, GenericArg, GenericBound, GenericParam, GenericParamKind, Generics, ImplItem, ImplItemKind, Item,
- ItemKind, Lifetime, LifetimeName, ParamName, QPath, TraitBoundModifier, TraitFn, TraitItem, TraitItemKind, Ty,
- TyKind, WhereClause, WherePredicate,
+ BareFnTy, BodyId, FnDecl, GenericArg, GenericBound, GenericParam, GenericParamKind, Generics, Impl, ImplItem,
+ ImplItemKind, Item, ItemKind, LangItem, Lifetime, LifetimeName, ParamName, PolyTraitRef, PredicateOrigin,
+ TraitBoundModifier, TraitFn, TraitItem, TraitItemKind, Ty, TyKind, WherePredicate,
};
use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::hir::map::Map;
+use rustc_middle::hir::nested_filter as middle_nested_filter;
+use rustc_middle::ty::TyCtxt;
use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::def_id::LocalDefId;
use rustc_span::source_map::Span;
-use rustc_span::symbol::kw;
-
-use crate::reexport::Name;
-use crate::utils::{in_macro, last_path_segment, span_lint, trait_ref_of_method};
+use rustc_span::symbol::{kw, Ident, Symbol};
declare_clippy_lint! {
- /// **What it does:** Checks for lifetime annotations which can be removed by
+ /// ### What it does
+ /// Checks for lifetime annotations which can be removed by
/// relying on lifetime elision.
///
- /// **Why is this bad?** The additional lifetimes make the code look more
+ /// ### Why is this bad?
+ /// The additional lifetimes make the code look more
/// complicated, while there is nothing out of the ordinary going on. Removing
/// them leads to more readable code.
///
- /// **Known problems:** Potential false negatives: we bail out if the function
- /// has a `where` clause where lifetimes are mentioned.
+ /// ### Known problems
+ /// - We bail out if the function has a `where` clause where lifetimes
+ /// are mentioned due to potential false positives.
+ /// - Lifetime bounds such as `impl Foo + 'a` and `T: 'a` must be elided with the
+ /// placeholder notation `'_` because the fully elided notation leaves the type bound to `'static`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
- /// // Bad: unnecessary lifetime annotations
+ /// // Unnecessary lifetime annotations
/// fn in_and_out<'a>(x: &'a u8, y: u8) -> &'a u8 {
/// x
/// }
+ /// ```
///
- /// // Good
+ /// Use instead:
+ /// ```rust
/// fn elided(x: &u8, y: u8) -> &u8 {
/// x
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub NEEDLESS_LIFETIMES,
complexity,
"using explicit lifetimes for references in function arguments when elision rules \
}
declare_clippy_lint! {
- /// **What it does:** Checks for lifetimes in generics that are never used
+ /// ### What it does
+ /// Checks for lifetimes in generics that are never used
/// anywhere else.
///
- /// **Why is this bad?** The additional lifetimes make the code look more
+ /// ### Why is this bad?
+ /// The additional lifetimes make the code look more
/// complicated, while there is nothing out of the ordinary going on. Removing
/// them leads to more readable code.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
- /// // Bad: unnecessary lifetimes
+ /// // unnecessary lifetimes
/// fn unused_lifetime<'a>(x: u8) {
/// // ..
/// }
+ /// ```
///
- /// // Good
+ /// Use instead:
+ /// ```rust
/// fn no_lifetime(x: u8) {
/// // ...
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub EXTRA_UNUSED_LIFETIMES,
complexity,
"unused lifetimes in function definitions"
declare_lint_pass!(Lifetimes => [NEEDLESS_LIFETIMES, EXTRA_UNUSED_LIFETIMES]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Lifetimes {
- fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item<'_>) {
- if let ItemKind::Fn(ref sig, ref generics, id) = item.kind {
- check_fn_inner(cx, &sig.decl, Some(id), generics, item.span, true);
+impl<'tcx> LateLintPass<'tcx> for Lifetimes {
+ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
+ if let ItemKind::Fn(ref sig, generics, id) = item.kind {
+ check_fn_inner(cx, sig.decl, Some(id), None, generics, item.span, true);
+ } else if let ItemKind::Impl(impl_) = item.kind {
+ if !item.span.from_expansion() {
+ report_extra_impl_lifetimes(cx, impl_);
+ }
}
}
- fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem<'_>) {
+ fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
if let ImplItemKind::Fn(ref sig, id) = item.kind {
- let report_extra_lifetimes = trait_ref_of_method(cx, item.hir_id).is_none();
+ let report_extra_lifetimes = trait_ref_of_method(cx, item.def_id).is_none();
check_fn_inner(
cx,
- &sig.decl,
+ sig.decl,
Some(id),
- &item.generics,
+ None,
+ item.generics,
item.span,
report_extra_lifetimes,
);
}
}
- fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem<'_>) {
+ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
if let TraitItemKind::Fn(ref sig, ref body) = item.kind {
- let body = match *body {
- TraitFn::Required(_) => None,
- TraitFn::Provided(id) => Some(id),
+ let (body, trait_sig) = match *body {
+ TraitFn::Required(sig) => (None, Some(sig)),
+ TraitFn::Provided(id) => (Some(id), None),
};
- check_fn_inner(cx, &sig.decl, body, &item.generics, item.span, true);
+ check_fn_inner(cx, sig.decl, body, trait_sig, item.generics, item.span, true);
}
}
}
/// The lifetime of a &-reference.
-#[derive(PartialEq, Eq, Hash, Debug)]
+#[derive(PartialEq, Eq, Hash, Debug, Clone)]
enum RefLt {
Unnamed,
Static,
- Named(Name),
+ Named(LocalDefId),
}
-fn check_fn_inner<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
+fn check_fn_inner<'tcx>(
+ cx: &LateContext<'tcx>,
decl: &'tcx FnDecl<'_>,
body: Option<BodyId>,
+ trait_sig: Option<&[Ident]>,
generics: &'tcx Generics<'_>,
span: Span,
report_extra_lifetimes: bool,
) {
- if in_macro(span) || has_where_lifetimes(cx, &generics.where_clause) {
+ if span.from_expansion() || has_where_lifetimes(cx, generics) {
return;
}
- let mut bounds_lts = Vec::new();
- let types = generics.params.iter().filter(|param| match param.kind {
- GenericParamKind::Type { .. } => true,
- _ => false,
- });
+ let types = generics
+ .params
+ .iter()
+ .filter(|param| matches!(param.kind, GenericParamKind::Type { .. }));
for typ in types {
- for bound in typ.bounds {
- let mut visitor = RefVisitor::new(cx);
- walk_param_bound(&mut visitor, bound);
- if visitor.lts.iter().any(|lt| matches!(lt, RefLt::Named(_))) {
- return;
+ for pred in generics.bounds_for_param(cx.tcx.hir().local_def_id(typ.hir_id)) {
+ if pred.origin == PredicateOrigin::WhereClause {
+ // has_where_lifetimes checked that this predicate contains no lifetime.
+ continue;
}
- if let GenericBound::Trait(ref trait_ref, _) = *bound {
- let params = &trait_ref
- .trait_ref
- .path
- .segments
- .last()
- .expect("a path must have at least one segment")
- .args;
- if let Some(ref params) = *params {
- let lifetimes = params.args.iter().filter_map(|arg| match arg {
- GenericArg::Lifetime(lt) => Some(lt),
- _ => None,
- });
- for bound in lifetimes {
- if bound.name != LifetimeName::Static && !bound.is_elided() {
- return;
+
+ for bound in pred.bounds {
+ let mut visitor = RefVisitor::new(cx);
+ walk_param_bound(&mut visitor, bound);
+ if visitor.lts.iter().any(|lt| matches!(lt, RefLt::Named(_))) {
+ return;
+ }
+ if let GenericBound::Trait(ref trait_ref, _) = *bound {
+ let params = &trait_ref
+ .trait_ref
+ .path
+ .segments
+ .last()
+ .expect("a path must have at least one segment")
+ .args;
+ if let Some(params) = *params {
+ let lifetimes = params.args.iter().filter_map(|arg| match arg {
+ GenericArg::Lifetime(lt) => Some(lt),
+ _ => None,
+ });
+ for bound in lifetimes {
+ if bound.name != LifetimeName::Static && !bound.is_elided() {
+ return;
+ }
}
- bounds_lts.push(bound);
}
}
}
}
}
- if could_use_elision(cx, decl, body, &generics.params, bounds_lts) {
+ if could_use_elision(cx, decl, body, trait_sig, generics.params) {
span_lint(
cx,
NEEDLESS_LIFETIMES,
}
}
-fn could_use_elision<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
+// elision doesn't work for explicit self types, see rust-lang/rust#69064
+fn explicit_self_type<'tcx>(cx: &LateContext<'tcx>, func: &FnDecl<'tcx>, ident: Option<Ident>) -> bool {
+ if_chain! {
+ if let Some(ident) = ident;
+ if ident.name == kw::SelfLower;
+ if !func.implicit_self.has_implicit_self();
+
+ if let Some(self_ty) = func.inputs.first();
+ then {
+ let mut visitor = RefVisitor::new(cx);
+ visitor.visit_ty(self_ty);
+
+ !visitor.all_lts().is_empty()
+ } else {
+ false
+ }
+ }
+}
+
+fn could_use_elision<'tcx>(
+ cx: &LateContext<'tcx>,
func: &'tcx FnDecl<'_>,
body: Option<BodyId>,
+ trait_sig: Option<&[Ident]>,
named_generics: &'tcx [GenericParam<'_>],
- bounds_lts: Vec<&'tcx Lifetime>,
) -> bool {
// There are two scenarios where elision works:
// * no output references, all input references have different LT
// level of the current item.
// check named LTs
- let allowed_lts = allowed_lts_from(named_generics);
+ let allowed_lts = allowed_lts_from(cx.tcx, named_generics);
// these will collect all the lifetimes for references in arg/return types
let mut input_visitor = RefVisitor::new(cx);
input_visitor.visit_ty(arg);
}
// extract lifetimes in output type
- if let Return(ref ty) = func.output {
+ if let Return(ty) = func.output {
output_visitor.visit_ty(ty);
}
+ for lt in named_generics {
+ input_visitor.visit_generic_param(lt);
+ }
+
+ if input_visitor.abort() || output_visitor.abort() {
+ return false;
+ }
- let input_lts = match input_visitor.into_vec() {
- Some(lts) => lts_from_bounds(lts, bounds_lts.into_iter()),
- None => return false,
- };
- let output_lts = match output_visitor.into_vec() {
- Some(val) => val,
- None => return false,
- };
+ let input_lts = input_visitor.lts;
+ let output_lts = output_visitor.lts;
+
+ if let Some(trait_sig) = trait_sig {
+ if explicit_self_type(cx, func, trait_sig.first().copied()) {
+ return false;
+ }
+ }
if let Some(body_id) = body {
+ let body = cx.tcx.hir().body(body_id);
+
+ let first_ident = body.params.first().and_then(|param| param.pat.simple_ident());
+ if explicit_self_type(cx, func, first_ident) {
+ return false;
+ }
+
let mut checker = BodyLifetimeChecker {
lifetimes_used_in_body: false,
};
- checker.visit_expr(&cx.tcx.hir().body(body_id).value);
+ checker.visit_expr(&body.value);
if checker.lifetimes_used_in_body {
return false;
}
}
}
+ // check for higher-ranked trait bounds
+ if !input_visitor.nested_elision_site_lts.is_empty() || !output_visitor.nested_elision_site_lts.is_empty() {
+ let allowed_lts: FxHashSet<_> = allowed_lts
+ .iter()
+ .filter_map(|lt| match lt {
+ RefLt::Named(def_id) => Some(cx.tcx.item_name(def_id.to_def_id())),
+ _ => None,
+ })
+ .collect();
+ for lt in input_visitor.nested_elision_site_lts {
+ if let RefLt::Named(def_id) = lt {
+ if allowed_lts.contains(&cx.tcx.item_name(def_id.to_def_id())) {
+ return false;
+ }
+ }
+ }
+ for lt in output_visitor.nested_elision_site_lts {
+ if let RefLt::Named(def_id) = lt {
+ if allowed_lts.contains(&cx.tcx.item_name(def_id.to_def_id())) {
+ return false;
+ }
+ }
+ }
+ }
+
// no input lifetimes? easy case!
if input_lts.is_empty() {
false
}
}
-fn allowed_lts_from(named_generics: &[GenericParam<'_>]) -> FxHashSet<RefLt> {
+fn allowed_lts_from(tcx: TyCtxt<'_>, named_generics: &[GenericParam<'_>]) -> FxHashSet<RefLt> {
let mut allowed_lts = FxHashSet::default();
for par in named_generics.iter() {
if let GenericParamKind::Lifetime { .. } = par.kind {
- if par.bounds.is_empty() {
- allowed_lts.insert(RefLt::Named(par.name.ident().name));
- }
+ allowed_lts.insert(RefLt::Named(tcx.hir().local_def_id(par.hir_id)));
}
}
allowed_lts.insert(RefLt::Unnamed);
allowed_lts
}
-fn lts_from_bounds<'a, T: Iterator<Item = &'a Lifetime>>(mut vec: Vec<RefLt>, bounds_lts: T) -> Vec<RefLt> {
- for lt in bounds_lts {
- if lt.name != LifetimeName::Static {
- vec.push(RefLt::Named(lt.name.ident().name));
- }
- }
-
- vec
-}
-
/// Number of unique lifetimes in the given vector.
#[must_use]
fn unique_lifetimes(lts: &[RefLt]) -> usize {
lts.iter().collect::<FxHashSet<_>>().len()
}
+const CLOSURE_TRAIT_BOUNDS: [LangItem; 3] = [LangItem::Fn, LangItem::FnMut, LangItem::FnOnce];
+
/// A visitor usable for `rustc_front::visit::walk_ty()`.
struct RefVisitor<'a, 'tcx> {
- cx: &'a LateContext<'a, 'tcx>,
+ cx: &'a LateContext<'tcx>,
lts: Vec<RefLt>,
- abort: bool,
+ nested_elision_site_lts: Vec<RefLt>,
+ unelided_trait_object_lifetime: bool,
}
-impl<'v, 't> RefVisitor<'v, 't> {
- fn new(cx: &'v LateContext<'v, 't>) -> Self {
+impl<'a, 'tcx> RefVisitor<'a, 'tcx> {
+ fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
lts: Vec::new(),
- abort: false,
+ nested_elision_site_lts: Vec::new(),
+ unelided_trait_object_lifetime: false,
}
}
if let Some(ref lt) = *lifetime {
if lt.name == LifetimeName::Static {
self.lts.push(RefLt::Static);
- } else if let LifetimeName::Param(ParamName::Fresh(_)) = lt.name {
+ } else if let LifetimeName::Param(_, ParamName::Fresh) = lt.name {
// Fresh lifetimes generated should be ignored.
+ self.lts.push(RefLt::Unnamed);
} else if lt.is_elided() {
self.lts.push(RefLt::Unnamed);
+ } else if let LifetimeName::Param(def_id, _) = lt.name {
+ self.lts.push(RefLt::Named(def_id));
} else {
- self.lts.push(RefLt::Named(lt.name.ident().name));
+ self.lts.push(RefLt::Unnamed);
}
} else {
self.lts.push(RefLt::Unnamed);
}
}
- fn into_vec(self) -> Option<Vec<RefLt>> {
- if self.abort {
- None
- } else {
- Some(self.lts)
- }
+ fn all_lts(&self) -> Vec<RefLt> {
+ self.lts
+ .iter()
+ .chain(self.nested_elision_site_lts.iter())
+ .cloned()
+ .collect::<Vec<_>>()
}
- fn collect_anonymous_lifetimes(&mut self, qpath: &QPath<'_>, ty: &Ty<'_>) {
- if let Some(ref last_path_segment) = last_path_segment(qpath).args {
- if !last_path_segment.parenthesized
- && !last_path_segment.args.iter().any(|arg| match arg {
- GenericArg::Lifetime(_) => true,
- _ => false,
- })
- {
- let hir_id = ty.hir_id;
- match self.cx.tables.qpath_res(qpath, hir_id) {
- Res::Def(DefKind::TyAlias | DefKind::Struct, def_id) => {
- let generics = self.cx.tcx.generics_of(def_id);
- for _ in generics.params.as_slice() {
- self.record(&None);
- }
- },
- Res::Def(DefKind::Trait, def_id) => {
- let trait_def = self.cx.tcx.trait_def(def_id);
- for _ in &self.cx.tcx.generics_of(trait_def.def_id).params {
- self.record(&None);
- }
- },
- _ => (),
- }
- }
- }
+ fn abort(&self) -> bool {
+ self.unelided_trait_object_lifetime
}
}
impl<'a, 'tcx> Visitor<'tcx> for RefVisitor<'a, 'tcx> {
- type Map = Map<'tcx>;
-
// for lifetimes as parameters of generics
fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) {
self.record(&Some(*lifetime));
}
+ fn visit_poly_trait_ref(&mut self, poly_tref: &'tcx PolyTraitRef<'tcx>, tbm: TraitBoundModifier) {
+ let trait_ref = &poly_tref.trait_ref;
+ if CLOSURE_TRAIT_BOUNDS.iter().any(|&item| {
+ self.cx
+ .tcx
+ .lang_items()
+ .require(item)
+ .map_or(false, |id| Some(id) == trait_ref.trait_def_id())
+ }) {
+ let mut sub_visitor = RefVisitor::new(self.cx);
+ sub_visitor.visit_trait_ref(trait_ref);
+ self.nested_elision_site_lts.append(&mut sub_visitor.all_lts());
+ } else {
+ walk_poly_trait_ref(self, poly_tref, tbm);
+ }
+ }
+
fn visit_ty(&mut self, ty: &'tcx Ty<'_>) {
match ty.kind {
- TyKind::Rptr(ref lt, _) if lt.is_elided() => {
- self.record(&None);
- },
- TyKind::Path(ref path) => {
- self.collect_anonymous_lifetimes(path, ty);
- },
- TyKind::Def(item, _) => {
+ TyKind::OpaqueDef(item, bounds) => {
let map = self.cx.tcx.hir();
- if let ItemKind::OpaqueTy(ref exist_ty) = map.expect_item(item.id).kind {
- for bound in exist_ty.bounds {
- if let GenericBound::Outlives(_) = *bound {
- self.record(&None);
- }
- }
- } else {
- unreachable!()
- }
- walk_ty(self, ty);
+ let item = map.item(item);
+ let len = self.lts.len();
+ walk_item(self, item);
+ self.lts.truncate(len);
+ self.lts.extend(bounds.iter().filter_map(|bound| match bound {
+ GenericArg::Lifetime(l) => Some(if let LifetimeName::Param(def_id, _) = l.name {
+ RefLt::Named(def_id)
+ } else {
+ RefLt::Unnamed
+ }),
+ _ => None,
+ }));
+ },
+ TyKind::BareFn(&BareFnTy { decl, .. }) => {
+ let mut sub_visitor = RefVisitor::new(self.cx);
+ sub_visitor.visit_fn_decl(decl);
+ self.nested_elision_site_lts.append(&mut sub_visitor.all_lts());
},
- TyKind::TraitObject(bounds, ref lt) => {
+ TyKind::TraitObject(bounds, ref lt, _) => {
if !lt.is_elided() {
- self.abort = true;
+ self.unelided_trait_object_lifetime = true;
}
for bound in bounds {
self.visit_poly_trait_ref(bound, TraitBoundModifier::None);
}
- return;
},
- _ => (),
+ _ => walk_ty(self, ty),
}
- walk_ty(self, ty);
- }
- fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
- NestedVisitorMap::None
}
}
/// Are any lifetimes mentioned in the `where` clause? If so, we don't try to
/// reason about elision.
-fn has_where_lifetimes<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, where_clause: &'tcx WhereClause<'_>) -> bool {
- for predicate in where_clause.predicates {
+fn has_where_lifetimes<'tcx>(cx: &LateContext<'tcx>, generics: &'tcx Generics<'_>) -> bool {
+ for predicate in generics.predicates {
match *predicate {
WherePredicate::RegionPredicate(..) => return true,
WherePredicate::BoundPredicate(ref pred) => {
// a predicate like F: Trait or F: for<'a> Trait<'a>
let mut visitor = RefVisitor::new(cx);
// walk the type F, it may not contain LT refs
- walk_ty(&mut visitor, &pred.bounded_ty);
- if !visitor.lts.is_empty() {
+ walk_ty(&mut visitor, pred.bounded_ty);
+ if !visitor.all_lts().is_empty() {
return true;
}
// if the bounds define new lifetimes, they are fine to occur
- let allowed_lts = allowed_lts_from(&pred.bound_generic_params);
+ let allowed_lts = allowed_lts_from(cx.tcx, pred.bound_generic_params);
// now walk the bounds
for bound in pred.bounds.iter() {
walk_param_bound(&mut visitor, bound);
}
// and check that all lifetimes are allowed
- match visitor.into_vec() {
- None => return false,
- Some(lts) => {
- for lt in lts {
- if !allowed_lts.contains(<) {
- return true;
- }
- }
- },
+ if visitor.all_lts().iter().any(|it| !allowed_lts.contains(it)) {
+ return true;
}
},
WherePredicate::EqPredicate(ref pred) => {
let mut visitor = RefVisitor::new(cx);
- walk_ty(&mut visitor, &pred.lhs_ty);
- walk_ty(&mut visitor, &pred.rhs_ty);
+ walk_ty(&mut visitor, pred.lhs_ty);
+ walk_ty(&mut visitor, pred.rhs_ty);
if !visitor.lts.is_empty() {
return true;
}
false
}
-struct LifetimeChecker {
- map: FxHashMap<Name, Span>,
+struct LifetimeChecker<'cx, 'tcx, F> {
+ cx: &'cx LateContext<'tcx>,
+ map: FxHashMap<Symbol, Span>,
+ phantom: std::marker::PhantomData<F>,
}
-impl<'tcx> Visitor<'tcx> for LifetimeChecker {
- type Map = Map<'tcx>;
+impl<'cx, 'tcx, F> LifetimeChecker<'cx, 'tcx, F> {
+ fn new(cx: &'cx LateContext<'tcx>, map: FxHashMap<Symbol, Span>) -> LifetimeChecker<'cx, 'tcx, F> {
+ Self {
+ cx,
+ map,
+ phantom: std::marker::PhantomData,
+ }
+ }
+}
+
+impl<'cx, 'tcx, F> Visitor<'tcx> for LifetimeChecker<'cx, 'tcx, F>
+where
+ F: NestedFilter<'tcx>,
+{
+ type Map = rustc_middle::hir::map::Map<'tcx>;
+ type NestedFilter = F;
// for lifetimes as parameters of generics
fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) {
// `'b` in `'a: 'b` is useless unless used elsewhere in
// a non-lifetime bound
if let GenericParamKind::Type { .. } = param.kind {
- walk_generic_param(self, param)
+ walk_generic_param(self, param);
}
}
- fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
- NestedVisitorMap::None
+
+ fn nested_visit_map(&mut self) -> Self::Map {
+ self.cx.tcx.hir()
}
}
-fn report_extra_lifetimes<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, func: &'tcx FnDecl<'_>, generics: &'tcx Generics<'_>) {
+fn report_extra_lifetimes<'tcx>(cx: &LateContext<'tcx>, func: &'tcx FnDecl<'_>, generics: &'tcx Generics<'_>) {
let hs = generics
.params
.iter()
_ => None,
})
.collect();
- let mut checker = LifetimeChecker { map: hs };
+ let mut checker = LifetimeChecker::<hir_nested_filter::None>::new(cx, hs);
walk_generics(&mut checker, generics);
walk_fn_decl(&mut checker, func);
}
}
+fn report_extra_impl_lifetimes<'tcx>(cx: &LateContext<'tcx>, impl_: &'tcx Impl<'_>) {
+ let hs = impl_
+ .generics
+ .params
+ .iter()
+ .filter_map(|par| match par.kind {
+ GenericParamKind::Lifetime { .. } => Some((par.name.ident().name, par.span)),
+ _ => None,
+ })
+ .collect();
+ let mut checker = LifetimeChecker::<middle_nested_filter::All>::new(cx, hs);
+
+ walk_generics(&mut checker, impl_.generics);
+ if let Some(ref trait_ref) = impl_.of_trait {
+ walk_trait_ref(&mut checker, trait_ref);
+ }
+ walk_ty(&mut checker, impl_.self_ty);
+ for item in impl_.items {
+ walk_impl_item_ref(&mut checker, item);
+ }
+
+ for &v in checker.map.values() {
+ span_lint(cx, EXTRA_UNUSED_LIFETIMES, v, "this lifetime isn't used in the impl");
+ }
+}
+
struct BodyLifetimeChecker {
lifetimes_used_in_body: bool,
}
impl<'tcx> Visitor<'tcx> for BodyLifetimeChecker {
- type Map = Map<'tcx>;
-
// for lifetimes as parameters of generics
fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) {
- if lifetime.name.ident().name != kw::Invalid && lifetime.name.ident().name != kw::StaticLifetime {
+ if lifetime.name.ident().name != kw::UnderscoreLifetime && lifetime.name.ident().name != kw::StaticLifetime {
self.lifetimes_used_in_body = true;
}
}
-
- fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
- NestedVisitorMap::None
- }
}
projects / rust.git / blobdiff