-use matches::matches;
-use rustc::hir::def::{DefKind, Res};
-use rustc::hir::intravisit::*;
-use rustc::hir::*;
-use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
+use crate::utils::paths;
+use crate::utils::{get_trait_def_id, in_macro, span_lint, trait_ref_of_method};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use syntax::source_map::Span;
-use syntax::symbol::kw;
-
-use crate::reexport::*;
-use crate::utils::{last_path_segment, span_lint, trait_ref_of_method};
+use rustc_hir::intravisit::{
+ walk_fn_decl, walk_generic_param, walk_generics, walk_item, walk_param_bound, walk_poly_trait_ref, walk_ty,
+ NestedVisitorMap, Visitor,
+};
+use rustc_hir::FnRetTy::Return;
+use rustc_hir::{
+ BareFnTy, BodyId, FnDecl, GenericArg, GenericBound, GenericParam, GenericParamKind, Generics, ImplItem,
+ ImplItemKind, Item, ItemKind, Lifetime, LifetimeName, ParamName, PolyTraitRef, TraitBoundModifier, TraitFn,
+ TraitItem, TraitItemKind, Ty, TyKind, WhereClause, WherePredicate,
+};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::hir::map::Map;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+use rustc_span::symbol::{kw, Symbol};
declare_clippy_lint! {
/// **What it does:** Checks for lifetime annotations which can be removed by
/// 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 potenial 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:**
/// ```rust
+ /// // Bad: unnecessary lifetime annotations
/// fn in_and_out<'a>(x: &'a u8, y: u8) -> &'a u8 {
/// x
/// }
+ ///
+ /// // Good
+ /// fn elided(x: &u8, y: u8) -> &u8 {
+ /// x
+ /// }
/// ```
pub NEEDLESS_LIFETIMES,
complexity,
///
/// **Example:**
/// ```rust
+ /// // Bad: unnecessary lifetimes
/// fn unused_lifetime<'a>(x: u8) {
/// // ..
/// }
+ ///
+ /// // Good
+ /// fn no_lifetime(x: u8) {
+ /// // ...
+ /// }
/// ```
pub EXTRA_UNUSED_LIFETIMES,
complexity,
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 decl, _, ref generics, id) = item.kind {
- check_fn_inner(cx, 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, ref generics, id) = item.kind {
+ check_fn_inner(cx, &sig.decl, Some(id), generics, item.span, true);
}
}
- fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) {
- if let ImplItemKind::Method(ref sig, id) = item.kind {
+ 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();
check_fn_inner(
cx,
}
}
- fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) {
- if let TraitItemKind::Method(ref sig, ref body) = item.kind {
+ 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 {
- TraitMethod::Required(_) => None,
- TraitMethod::Provided(id) => Some(id),
+ TraitFn::Required(_) => None,
+ TraitFn::Provided(id) => Some(id),
};
check_fn_inner(cx, &sig.decl, body, &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(Symbol),
}
-fn check_fn_inner<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- decl: &'tcx FnDecl,
+fn check_fn_inner<'tcx>(
+ cx: &LateContext<'tcx>,
+ decl: &'tcx FnDecl<'_>,
body: Option<BodyId>,
- generics: &'tcx Generics,
+ generics: &'tcx Generics<'_>,
span: Span,
report_extra_lifetimes: bool,
) {
- if in_external_macro(cx.sess(), span) || has_where_lifetimes(cx, &generics.where_clause) {
+ if in_macro(span) || has_where_lifetimes(cx, &generics.where_clause) {
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 {
+ 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(_))) {
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, &generics.params) {
span_lint(
cx,
NEEDLESS_LIFETIMES,
- span,
+ span.with_hi(decl.output.span().hi()),
"explicit lifetimes given in parameter types where they could be elided \
(or replaced with `'_` if needed by type declaration)",
);
}
}
-fn could_use_elision<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- func: &'tcx FnDecl,
+fn could_use_elision<'tcx>(
+ cx: &LateContext<'tcx>,
+ func: &'tcx FnDecl<'_>,
body: Option<BodyId>,
- named_generics: &'tcx [GenericParam],
- bounds_lts: Vec<&'tcx Lifetime>,
+ named_generics: &'tcx [GenericParam<'_>],
) -> bool {
// There are two scenarios where elision works:
// * no output references, all input references have different LT
let mut output_visitor = RefVisitor::new(cx);
// extract lifetimes in input argument types
- for arg in &func.inputs {
+ for arg in func.inputs {
input_visitor.visit_ty(arg);
}
// extract lifetimes in output type
if let Return(ref 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,
- };
+ if allowed_lts
+ .intersection(
+ &input_visitor
+ .nested_elision_site_lts
+ .iter()
+ .chain(output_visitor.nested_elision_site_lts.iter())
+ .cloned()
+ .filter(|v| matches!(v, RefLt::Named(_)))
+ .collect(),
+ )
+ .next()
+ .is_some()
+ {
+ return false;
+ }
+
+ let input_lts = input_visitor.lts;
+ let output_lts = output_visitor.lts;
if let Some(body_id) = body {
let mut checker = BodyLifetimeChecker {
}
}
-fn allowed_lts_from(named_generics: &[GenericParam]) -> FxHashSet<RefLt> {
+fn allowed_lts_from(named_generics: &[GenericParam<'_>]) -> FxHashSet<RefLt> {
let mut allowed_lts = FxHashSet::default();
for par in named_generics.iter() {
if let GenericParamKind::Lifetime { .. } = par.kind {
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: [&[&str]; 3] = [&paths::FN, &paths::FN_MUT, &paths::FN_ONCE];
+
/// 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,
}
}
}
}
- 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, def_id) | Res::Def(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_ty(&mut self, ty: &'tcx Ty) {
+ 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(|trait_path| trait_ref.trait_def_id() == get_trait_def_id(self.cx, trait_path))
+ {
+ 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, _) => {
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!()
- }
+ let item = map.expect_item(item.id);
+ walk_item(self, item);
walk_ty(self, ty);
},
- TyKind::TraitObject(ref bounds, ref lt) => {
+ 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());
+ return;
+ },
+ 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);
}
walk_ty(self, ty);
}
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ 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>, where_clause: &'tcx WhereClause<'_>) -> bool {
+ for predicate in where_clause.predicates {
match *predicate {
WherePredicate::RegionPredicate(..) => return true,
WherePredicate::BoundPredicate(ref pred) => {
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() {
+ if !visitor.all_lts().is_empty() {
return true;
}
// if the bounds define new lifetimes, they are fine to occur
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) => {
}
struct LifetimeChecker {
- map: FxHashMap<Name, Span>,
+ map: FxHashMap<Symbol, Span>,
}
impl<'tcx> Visitor<'tcx> for LifetimeChecker {
+ type Map = Map<'tcx>;
+
// for lifetimes as parameters of generics
fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) {
self.map.remove(&lifetime.name.ident().name);
}
- fn visit_generic_param(&mut self, param: &'tcx GenericParam) {
+ fn visit_generic_param(&mut self, param: &'tcx GenericParam<'_>) {
// don't actually visit `<'a>` or `<'a: 'b>`
// we've already visited the `'a` declarations and
// don't want to spuriously remove them
walk_generic_param(self, param)
}
}
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
-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()
}
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 {
}
}
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}
projects / rust.git / blobdiff