diff --git a/clippy_lints/src/escape.rs b/clippy_lints/src/escape.rs index d2dcb3e5c..9fcd17a75 100644 --- a/clippy_lints/src/escape.rs +++ b/clippy_lints/src/escape.rs @@ -1,15 +1,16 @@ use rustc_hir::intravisit; -use rustc_hir::{self, Body, FnDecl, HirId, HirIdSet, ItemKind, Node}; +use rustc_hir::{self, AssocItemKind, Body, FnDecl, HirId, HirIdSet, ItemKind, Node}; use rustc_infer::infer::TyCtxtInferExt; use rustc_lint::{LateContext, LateLintPass}; -use rustc_middle::ty::{self, Ty}; +use rustc_middle::ty::{self, TraitRef, Ty}; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::source_map::Span; +use rustc_span::symbol::kw; use rustc_target::abi::LayoutOf; use rustc_target::spec::abi::Abi; use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId}; -use crate::utils::span_lint; +use crate::utils::{contains_ty, span_lint}; #[derive(Copy, Clone)] pub struct BoxedLocal { @@ -51,6 +52,7 @@ fn is_non_trait_box(ty: Ty<'_>) -> bool { struct EscapeDelegate<'a, 'tcx> { cx: &'a LateContext<'tcx>, set: HirIdSet, + trait_self_ty: Option>, too_large_for_stack: u64, } @@ -72,19 +74,34 @@ impl<'tcx> LateLintPass<'tcx> for BoxedLocal { } } - // 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); + let mut trait_self_ty = None; if let Some(Node::Item(item)) = parent_node { + // If the method is an impl for a trait, don't warn. if let ItemKind::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 let AssocItemKind::Fn { has_self: true } = trait_item.kind { + trait_self_ty = + Some(TraitRef::identity(cx.tcx, trait_item.id.hir_id.owner.to_def_id()).self_ty()); + } + } + } + } } let mut v = EscapeDelegate { cx, set: HirIdSet::default(), + trait_self_ty, too_large_for_stack: self.too_large_for_stack, }; @@ -153,6 +170,14 @@ impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> { return; } + // skip if there is a `self` parameter binding to a type + // that contains `Self` (i.e.: `self: Box`), see #4804 + if let Some(trait_self_ty) = self.trait_self_ty { + if map.name(cmt.hir_id) == kw::SelfLower && contains_ty(cmt.place.ty(), 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); } diff --git a/tests/ui/escape_analysis.rs b/tests/ui/escape_analysis.rs index 070044896..d26f48fc6 100644 --- a/tests/ui/escape_analysis.rs +++ b/tests/ui/escape_analysis.rs @@ -182,3 +182,23 @@ pub extern "C" fn do_not_warn_me(_c_pointer: Box) -> () {} #[rustfmt::skip] // Forces rustfmt to not add ABI pub extern fn do_not_warn_me_no_abi(_c_pointer: Box) -> () {} + +// Issue #4804 - default implementation in trait +mod issue4804 { + trait DefaultTraitImplTest { + // don't warn on `self` + fn default_impl(self: Box) -> u32 { + 5 + } + + // warn on `x: Box` + fn default_impl_x(self: Box, x: Box) -> u32 { + 4 + } + } + + trait WarnTrait { + // warn on `x: Box` + fn foo(x: Box) {} + } +} diff --git a/tests/ui/escape_analysis.stderr b/tests/ui/escape_analysis.stderr index c86a769a3..4a82b4419 100644 --- a/tests/ui/escape_analysis.stderr +++ b/tests/ui/escape_analysis.stderr @@ -12,5 +12,17 @@ error: local variable doesn't need to be boxed here LL | pub fn new(_needs_name: Box>) -> () {} | ^^^^^^^^^^^ -error: aborting due to 2 previous errors +error: local variable doesn't need to be boxed here + --> $DIR/escape_analysis.rs:195:44 + | +LL | fn default_impl_x(self: Box, x: Box) -> u32 { + | ^ + +error: local variable doesn't need to be boxed here + --> $DIR/escape_analysis.rs:202:16 + | +LL | fn foo(x: Box) {} + | ^ + +error: aborting due to 4 previous errors