+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 rustc_hir::def::{DefKind, Res};
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_item, walk_param_bound, walk_poly_trait_ref, walk_ty,
+ NestedVisitorMap, 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, 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};
-
-use crate::utils::{in_macro, last_path_segment, span_lint, trait_ref_of_method};
+use std::iter::FromIterator;
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
}
/// The lifetime of a &-reference.
-#[derive(PartialEq, Eq, Hash, Debug)]
+#[derive(PartialEq, Eq, Hash, Debug, Clone)]
enum RefLt {
Unnamed,
Static,
return;
}
- let mut bounds_lts = Vec::new();
let types = generics
.params
.iter()
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,
func: &'tcx FnDecl<'_>,
body: Option<BodyId>,
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
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(&FxHashSet::from_iter(
+ input_visitor
+ .nested_elision_site_lts
+ .iter()
+ .chain(output_visitor.nested_elision_site_lts.iter())
+ .cloned()
+ .filter(|v| matches!(v, RefLt::Named(_))),
+ ))
+ .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 {
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<'tcx>,
lts: Vec<RefLt>,
- abort: bool,
+ nested_elision_site_lts: Vec<RefLt>,
+ unelided_trait_object_lifetime: bool,
}
impl<'a, 'tcx> RefVisitor<'a, 'tcx> {
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| matches!(arg, GenericArg::Lifetime(_)))
- {
- let hir_id = ty.hir_id;
- match self.cx.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
}
}
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(|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::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::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_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;
- }
- }
- },
- }
+ return visitor.all_lts().iter().any(|it| !allowed_lts.contains(it));
},
WherePredicate::EqPredicate(ref pred) => {
let mut visitor = RefVisitor::new(cx);
projects / rust.git / blobdiff