+use clippy_utils::diagnostics::span_lint_hir;
use rustc_hir::intravisit;
-use rustc_hir::{self, Body, FnDecl, HirId, HirIdSet, ItemKind, Node};
+use rustc_hir::{self, AssocItemKind, Body, FnDecl, HirId, HirIdSet, Impl, ItemKind, Node, Pat, PatKind};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::mir::FakeReadCause;
+use rustc_middle::ty::layout::LayoutOf;
+use rustc_middle::ty::{self, TraitRef, Ty};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
-use rustc_target::abi::LayoutOf;
-use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
-
-use crate::utils::span_lint;
+use rustc_span::symbol::kw;
+use rustc_target::spec::abi::Abi;
+use rustc_hir_analysis::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
#[derive(Copy, Clone)]
pub struct BoxedLocal {
}
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `Box<T>` where an unboxed `T` would
+ /// ### What it does
+ /// Checks for usage of `Box<T>` where an unboxed `T` would
/// work fine.
///
- /// **Why is this bad?** This is an unnecessary allocation, and bad for
+ /// ### Why is this bad?
+ /// This is an unnecessary allocation, and bad for
/// performance. It is only necessary to allocate if you wish to move the box
/// into something.
///
- /// **Known problems:** None.
+ /// ### Example
+ /// ```rust
+ /// fn foo(x: Box<u32>) {}
+ /// ```
///
- /// **Example:**
+ /// Use instead:
/// ```rust
- /// # fn foo(bar: usize) {}
- /// let x = Box::new(1);
- /// foo(*x);
- /// println!("{}", *x);
+ /// fn foo(x: u32) {}
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub BOXED_LOCAL,
perf,
"using `Box<T>` where unnecessary"
}
struct EscapeDelegate<'a, 'tcx> {
- cx: &'a LateContext<'a, 'tcx>,
+ cx: &'a LateContext<'tcx>,
set: HirIdSet,
+ trait_self_ty: Option<Ty<'tcx>>,
too_large_for_stack: u64,
}
impl_lint_pass!(BoxedLocal => [BOXED_LOCAL]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxedLocal {
+impl<'tcx> LateLintPass<'tcx> for BoxedLocal {
fn check_fn(
&mut self,
- cx: &LateContext<'a, 'tcx>,
- _: intravisit::FnKind<'tcx>,
+ cx: &LateContext<'tcx>,
+ fn_kind: intravisit::FnKind<'tcx>,
_: &'tcx FnDecl<'_>,
body: &'tcx Body<'_>,
_: Span,
hir_id: HirId,
) {
- // If the method is an impl for a trait, don't warn.
- let parent_id = cx.tcx.hir().get_parent_item(hir_id);
- let parent_node = cx.tcx.hir().find(parent_id);
+ if let Some(header) = fn_kind.header() {
+ if header.abi != Abi::Rust {
+ return;
+ }
+ }
+ let parent_id = cx.tcx.hir().get_parent_item(hir_id).def_id;
+ let parent_node = cx.tcx.hir().find_by_def_id(parent_id);
+
+ let mut trait_self_ty = None;
if let Some(Node::Item(item)) = parent_node {
- if let ItemKind::Impl { of_trait: Some(_), .. } = item.kind {
+ // If the method is an impl for a trait, don't warn.
+ if let ItemKind::Impl(Impl { of_trait: Some(_), .. }) = item.kind {
return;
}
+
+ // find `self` ty for this trait if relevant
+ if let ItemKind::Trait(_, _, _, _, items) = item.kind {
+ for trait_item in items {
+ if trait_item.id.hir_id() == hir_id {
+ // be sure we have `self` parameter in this function
+ if trait_item.kind == (AssocItemKind::Fn { has_self: true }) {
+ trait_self_ty = Some(
+ TraitRef::identity(cx.tcx, trait_item.id.def_id.to_def_id())
+ .self_ty()
+ .skip_binder(),
+ );
+ }
+ }
+ }
+ }
}
let mut v = EscapeDelegate {
cx,
set: HirIdSet::default(),
+ trait_self_ty,
too_large_for_stack: self.too_large_for_stack,
};
let fn_def_id = cx.tcx.hir().local_def_id(hir_id);
cx.tcx.infer_ctxt().enter(|infcx| {
- ExprUseVisitor::new(&mut v, &infcx, fn_def_id, cx.param_env, cx.tables).consume_body(body);
+ ExprUseVisitor::new(&mut v, &infcx, fn_def_id, cx.param_env, cx.typeck_results()).consume_body(body);
});
for node in v.set {
- span_lint(
+ span_lint_hir(
cx,
BOXED_LOCAL,
+ node,
cx.tcx.hir().span(node),
"local variable doesn't need to be boxed here",
);
// TODO: Replace with Map::is_argument(..) when it's fixed
fn is_argument(map: rustc_middle::hir::map::Map<'_>, id: HirId) -> bool {
match map.find(id) {
- Some(Node::Binding(_)) => (),
+ Some(Node::Pat(Pat {
+ kind: PatKind::Binding(..),
+ ..
+ })) => (),
_ => return false,
}
- match map.find(map.get_parent_node(id)) {
- Some(Node::Param(_)) => true,
- _ => false,
- }
+ matches!(map.find(map.get_parent_node(id)), Some(Node::Param(_)))
}
impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
- fn consume(&mut self, cmt: &Place<'tcx>, mode: ConsumeMode) {
- if cmt.projections.is_empty() {
- if let PlaceBase::Local(lid) = cmt.base {
- if let ConsumeMode::Move = mode {
- // moved out or in. clearly can't be localized
- self.set.remove(&lid);
- }
- let map = &self.cx.tcx.hir();
- if let Some(Node::Binding(_)) = map.find(cmt.hir_id) {
- if self.set.contains(&lid) {
- // let y = x where x is known
- // remove x, insert y
- self.set.insert(cmt.hir_id);
- self.set.remove(&lid);
- }
- }
+ fn consume(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
+ if cmt.place.projections.is_empty() {
+ if let PlaceBase::Local(lid) = cmt.place.base {
+ self.set.remove(&lid);
}
}
}
- fn borrow(&mut self, cmt: &Place<'tcx>, _: ty::BorrowKind) {
- if cmt.projections.is_empty() {
- if let PlaceBase::Local(lid) = cmt.base {
+ fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, _: ty::BorrowKind) {
+ if cmt.place.projections.is_empty() {
+ if let PlaceBase::Local(lid) = cmt.place.base {
self.set.remove(&lid);
}
}
}
- fn mutate(&mut self, cmt: &Place<'tcx>) {
- if cmt.projections.is_empty() {
+ fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId) {
+ if cmt.place.projections.is_empty() {
let map = &self.cx.tcx.hir();
if is_argument(*map, cmt.hir_id) {
// Skip closure arguments
return;
}
- if is_non_trait_box(cmt.ty) && !self.is_large_box(cmt.ty) {
+ // skip if there is a `self` parameter binding to a type
+ // that contains `Self` (i.e.: `self: Box<Self>`), see #4804
+ if let Some(trait_self_ty) = self.trait_self_ty {
+ if map.name(cmt.hir_id) == kw::SelfLower && cmt.place.ty().contains(trait_self_ty) {
+ return;
+ }
+ }
+
+ if is_non_trait_box(cmt.place.ty()) && !self.is_large_box(cmt.place.ty()) {
self.set.insert(cmt.hir_id);
}
- return;
}
}
}
+
+ fn fake_read(&mut self, _: &rustc_hir_analysis::expr_use_visitor::PlaceWithHirId<'tcx>, _: FakeReadCause, _: HirId) {}
}
impl<'a, 'tcx> EscapeDelegate<'a, 'tcx> {
projects / rust.git / blobdiff