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[DO NOT MERGE] Move trait perf test #146201

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15 changes: 8 additions & 7 deletions compiler/rustc_ast_lowering/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2101,24 +2101,25 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
{
return;
}
if self.tcx.features().more_maybe_bounds() {
return;
}
}
RelaxedBoundPolicy::Forbidden(reason) => {
if self.tcx.features().more_maybe_bounds() {
return;
}

match reason {
RelaxedBoundForbiddenReason::TraitObjectTy => {
if self.tcx.features().more_maybe_bounds() {
return;
}

self.dcx().span_err(
span,
"relaxed bounds are not permitted in trait object types",
);
return;
}
RelaxedBoundForbiddenReason::SuperTrait => {
if self.tcx.features().more_maybe_bounds() {
return;
}

let mut diag = self.dcx().struct_span_err(
span,
"relaxed bounds are not permitted in supertrait bounds",
Expand Down
6 changes: 0 additions & 6 deletions compiler/rustc_hir_analysis/src/collect/predicates_of.rs
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Expand Up @@ -174,12 +174,6 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
}
};

if let Node::TraitItem(item) = node {
let mut bounds = Vec::new();
icx.lowerer().add_default_trait_item_bounds(item, &mut bounds);
predicates.extend(bounds);
}

let generics = tcx.generics_of(def_id);

// Below we'll consider the bounds on the type parameters (including `Self`)
Expand Down
142 changes: 13 additions & 129 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
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@@ -1,12 +1,13 @@
use std::assert_matches::assert_matches;
use std::ops::ControlFlow;

use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_errors::codes::*;
use rustc_errors::struct_span_code_err;
use rustc_hir as hir;
use rustc_hir::PolyTraitRef;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
use rustc_hir::{AmbigArg, PolyTraitRef};
use rustc_middle::bug;
use rustc_middle::ty::{
self as ty, IsSuggestable, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
Expand Down Expand Up @@ -230,122 +231,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
}
}

/// Checks whether `Self: DefaultAutoTrait` bounds should be added on trait super bounds
/// or associated items.
///
/// To keep backward compatibility with existing code, `experimental_default_bounds` bounds
/// should be added everywhere, including super bounds. However this causes a huge performance
/// costs. For optimization purposes instead of adding default supertraits, bounds
/// are added to the associated items:
///
/// ```ignore(illustrative)
/// // Default bounds are generated in the following way:
/// trait Trait {
/// fn foo(&self) where Self: Leak {}
/// }
///
/// // instead of this:
/// trait Trait: Leak {
/// fn foo(&self) {}
/// }
/// ```
/// It is not always possible to do this because of backward compatibility:
///
/// ```ignore(illustrative)
/// pub trait Trait<Rhs = Self> {}
/// pub trait Trait1 : Trait {}
/// //~^ ERROR: `Rhs` requires `DefaultAutoTrait`, but `Self` is not `DefaultAutoTrait`
/// ```
///
/// or:
///
/// ```ignore(illustrative)
/// trait Trait {
/// type Type where Self: Sized;
/// }
/// trait Trait2<T> : Trait<Type = T> {}
/// //~^ ERROR: `DefaultAutoTrait` required for `Trait2`, by implicit `Self: DefaultAutoTrait` in `Trait::Type`
/// ```
///
/// Therefore, `experimental_default_bounds` are still being added to supertraits if
/// the `SelfTyParam` or `AssocItemConstraint` were found in a trait header.
fn requires_default_supertraits(
&self,
hir_bounds: &'tcx [hir::GenericBound<'tcx>],
hir_generics: &'tcx hir::Generics<'tcx>,
) -> bool {
struct TraitInfoCollector;

impl<'tcx> hir::intravisit::Visitor<'tcx> for TraitInfoCollector {
type Result = ControlFlow<()>;

fn visit_assoc_item_constraint(
&mut self,
_constraint: &'tcx hir::AssocItemConstraint<'tcx>,
) -> Self::Result {
ControlFlow::Break(())
}

fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx, AmbigArg>) -> Self::Result {
if matches!(
&t.kind,
hir::TyKind::Path(hir::QPath::Resolved(
_,
hir::Path { res: hir::def::Res::SelfTyParam { .. }, .. },
))
) {
return ControlFlow::Break(());
}
hir::intravisit::walk_ty(self, t)
}
}

let mut found = false;
for bound in hir_bounds {
found |= hir::intravisit::walk_param_bound(&mut TraitInfoCollector, bound).is_break();
}
found |= hir::intravisit::walk_generics(&mut TraitInfoCollector, hir_generics).is_break();
found
}

/// Implicitly add `Self: DefaultAutoTrait` clauses on trait associated items if
/// they are not added as super trait bounds to the trait itself. See
/// `requires_default_supertraits` for more information.
pub(crate) fn add_default_trait_item_bounds(
&self,
trait_item: &hir::TraitItem<'tcx>,
bounds: &mut Vec<(ty::Clause<'tcx>, Span)>,
) {
let tcx = self.tcx();
if !tcx.sess.opts.unstable_opts.experimental_default_bounds {
return;
}

let parent = tcx.local_parent(trait_item.hir_id().owner.def_id);
let hir::Node::Item(parent_trait) = tcx.hir_node_by_def_id(parent) else {
unreachable!();
};

let (trait_generics, trait_bounds) = match parent_trait.kind {
hir::ItemKind::Trait(_, _, _, _, generics, supertraits, _) => (generics, supertraits),
hir::ItemKind::TraitAlias(_, generics, supertraits) => (generics, supertraits),
_ => unreachable!(),
};

if !self.requires_default_supertraits(trait_bounds, trait_generics) {
let self_ty_where_predicates = (parent, trait_item.generics.predicates);
self.add_default_traits(
bounds,
tcx.types.self_param,
&[],
Some(self_ty_where_predicates),
trait_item.span,
);
}
}

/// Lazily sets `experimental_default_bounds` to true on trait super bounds.
/// See `requires_default_supertraits` for more information.
/// Sets `experimental_default_bounds` to true on trait super bounds.
pub(crate) fn add_default_super_traits(
&self,
trait_def_id: LocalDefId,
Expand All @@ -354,21 +240,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
hir_generics: &'tcx hir::Generics<'tcx>,
span: Span,
) {
if !self.tcx().sess.opts.unstable_opts.experimental_default_bounds {
assert_matches!(self.tcx().def_kind(trait_def_id), DefKind::Trait | DefKind::TraitAlias);

if self.tcx().trait_is_auto(trait_def_id.to_def_id()) {
return;
}

assert!(matches!(self.tcx().def_kind(trait_def_id), DefKind::Trait | DefKind::TraitAlias));
if self.requires_default_supertraits(hir_bounds, hir_generics) {
let self_ty_where_predicates = (trait_def_id, hir_generics.predicates);
self.add_default_traits(
bounds,
self.tcx().types.self_param,
hir_bounds,
Some(self_ty_where_predicates),
span,
);
}
self.add_default_traits(
bounds,
self.tcx().types.self_param,
hir_bounds,
Some((trait_def_id, hir_generics.predicates)),
span,
);
}

pub(crate) fn add_default_traits(
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_lint/src/multiple_supertrait_upcastable.rs
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Expand Up @@ -47,7 +47,8 @@ impl<'tcx> LateLintPass<'tcx> for MultipleSupertraitUpcastable {
.explicit_super_predicates_of(def_id)
.iter_identity_copied()
.filter_map(|(pred, _)| pred.as_trait_clause())
.filter(|pred| !cx.tcx.is_lang_item(pred.def_id(), hir::LangItem::MetaSized));
.filter(|pred| !cx.tcx.is_lang_item(pred.def_id(), hir::LangItem::MetaSized))
.filter(|pred| !cx.tcx.is_default_trait(pred.def_id()));
if direct_super_traits_iter.count() > 1 {
cx.emit_span_lint(
MULTIPLE_SUPERTRAIT_UPCASTABLE,
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_session/src/options.rs
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Expand Up @@ -2240,7 +2240,7 @@ options! {
"Use WebAssembly error handling for wasm32-unknown-emscripten"),
enforce_type_length_limit: bool = (false, parse_bool, [TRACKED],
"enforce the type length limit when monomorphizing instances in codegen"),
experimental_default_bounds: bool = (false, parse_bool, [TRACKED],
experimental_default_bounds: bool = (true, parse_bool, [TRACKED],
"enable default bounds for experimental group of auto traits"),
export_executable_symbols: bool = (false, parse_bool, [TRACKED],
"export symbols from executables, as if they were dynamic libraries"),
Expand Down
8 changes: 7 additions & 1 deletion library/alloc/src/boxed.rs
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Expand Up @@ -2039,7 +2039,10 @@ unsafe impl<T: ?Sized, A: Allocator> PinCoerceUnsized for Box<T, A> {}
// Handling arbitrary custom allocators (which can affect the `Box` layout heavily!)
// would need a lot of codegen and interpreter adjustments.
#[unstable(feature = "dispatch_from_dyn", issue = "none")]
impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T, Global> {}
impl<T: ?Sized + Unsize<U> + ?core::marker::Move, U: ?Sized + ?core::marker::Move>
DispatchFromDyn<Box<U>> for Box<T, Global>
{
}

#[stable(feature = "box_borrow", since = "1.1.0")]
impl<T: ?Sized, A: Allocator> Borrow<T> for Box<T, A> {
Expand Down Expand Up @@ -2141,3 +2144,6 @@ impl<E: Error> Error for Box<E> {
Error::provide(&**self, request);
}
}

#[unstable(feature = "move_trait", issue = "none")]
unsafe impl<T: ?Sized + ?core::marker::Move, A: Allocator> core::marker::Move for Box<T, A> {}
1 change: 1 addition & 0 deletions library/alloc/src/lib.rs
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Expand Up @@ -133,6 +133,7 @@
#![feature(local_waker)]
#![feature(maybe_uninit_slice)]
#![feature(maybe_uninit_uninit_array_transpose)]
#![feature(move_trait)]
#![feature(panic_internals)]
#![feature(pattern)]
#![feature(pin_coerce_unsized_trait)]
Expand Down
1 change: 1 addition & 0 deletions library/alloctests/tests/lib.rs
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Expand Up @@ -13,6 +13,7 @@
#![feature(int_format_into)]
#![feature(linked_list_cursors)]
#![feature(map_try_insert)]
#![feature(move_trait)]
#![feature(pattern)]
#![feature(trusted_len)]
#![feature(try_reserve_kind)]
Expand Down
21 changes: 12 additions & 9 deletions library/core/src/cell.rs
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Expand Up @@ -252,7 +252,7 @@

use crate::cmp::Ordering;
use crate::fmt::{self, Debug, Display};
use crate::marker::{PhantomData, Unsize};
use crate::marker::{Move, PhantomData, Unsize};
use crate::mem;
use crate::ops::{CoerceUnsized, Deref, DerefMut, DerefPure, DispatchFromDyn};
use crate::panic::const_panic;
Expand Down Expand Up @@ -309,7 +309,7 @@ pub use once::OnceCell;
#[stable(feature = "rust1", since = "1.0.0")]
#[repr(transparent)]
#[rustc_pub_transparent]
pub struct Cell<T: ?Sized> {
pub struct Cell<T: ?Sized + ?Move> {
value: UnsafeCell<T>,
}

Expand All @@ -322,7 +322,7 @@ unsafe impl<T: ?Sized> Send for Cell<T> where T: Send {}
// having an explicit negative impl is nice for documentation purposes
// and results in nicer error messages.
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> !Sync for Cell<T> {}
impl<T: ?Sized + ?Move> !Sync for Cell<T> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Copy> Clone for Cell<T> {
Expand Down Expand Up @@ -669,7 +669,7 @@ impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
// `self: Cell<&Self>` won't work
// `self: CellWrapper<Self>` becomes possible
#[unstable(feature = "dispatch_from_dyn", issue = "none")]
impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Cell<U>> for Cell<T> {}
impl<T: DispatchFromDyn<U> + ?Move, U: ?Move> DispatchFromDyn<Cell<U>> for Cell<T> {}

impl<T> Cell<[T]> {
/// Returns a `&[Cell<T>]` from a `&Cell<[T]>`
Expand Down Expand Up @@ -2185,12 +2185,12 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
#[stable(feature = "rust1", since = "1.0.0")]
#[repr(transparent)]
#[rustc_pub_transparent]
pub struct UnsafeCell<T: ?Sized> {
pub struct UnsafeCell<T: ?Sized + ?Move> {
value: T,
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> !Sync for UnsafeCell<T> {}
impl<T: ?Sized + ?Move> !Sync for UnsafeCell<T> {}

impl<T> UnsafeCell<T> {
/// Constructs a new instance of `UnsafeCell` which will wrap the specified
Expand Down Expand Up @@ -2455,7 +2455,7 @@ impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {}
// `self: UnsafeCell<&Self>` won't work
// `self: UnsafeCellWrapper<Self>` becomes possible
#[unstable(feature = "dispatch_from_dyn", issue = "none")]
impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T> {}
impl<T: DispatchFromDyn<U> + ?Move, U: ?Move> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T> {}

/// [`UnsafeCell`], but [`Sync`].
///
Expand All @@ -2473,7 +2473,7 @@ impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T>
#[repr(transparent)]
#[rustc_diagnostic_item = "SyncUnsafeCell"]
#[rustc_pub_transparent]
pub struct SyncUnsafeCell<T: ?Sized> {
pub struct SyncUnsafeCell<T: ?Sized + ?Move> {
value: UnsafeCell<T>,
}

Expand Down Expand Up @@ -2563,7 +2563,10 @@ impl<T: CoerceUnsized<U>, U> CoerceUnsized<SyncUnsafeCell<U>> for SyncUnsafeCell
// `self: SyncUnsafeCellWrapper<Self>` becomes possible
#[unstable(feature = "dispatch_from_dyn", issue = "none")]
//#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {}
impl<T: DispatchFromDyn<U> + ?Move, U: ?Move> DispatchFromDyn<SyncUnsafeCell<U>>
for SyncUnsafeCell<T>
{
}

#[allow(unused)]
fn assert_coerce_unsized(
Expand Down
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