diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs index 0083da2a1e4..149e7737e30 100644 --- a/compiler/rustc_hir_analysis/src/check/mod.rs +++ b/compiler/rustc_hir_analysis/src/check/mod.rs @@ -112,6 +112,7 @@ pub fn provide(providers: &mut Providers) { wfcheck::provide(providers); *providers = Providers { adt_destructor, + adt_async_destructor, region_scope_tree, collect_return_position_impl_trait_in_trait_tys, compare_impl_const: compare_impl_item::compare_impl_const_raw, @@ -124,6 +125,10 @@ fn adt_destructor(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option tcx.calculate_dtor(def_id.to_def_id(), dropck::check_drop_impl) } +fn adt_async_destructor(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option { + tcx.calculate_async_dtor(def_id.to_def_id(), dropck::check_drop_impl) +} + /// Given a `DefId` for an opaque type in return position, find its parent item's return /// expressions. fn get_owner_return_paths( diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs index 4cad317ce80..f6b9c7ed992 100644 --- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs +++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs @@ -287,6 +287,10 @@ fn into_args(self) -> (DefId, SimplifiedType) { let _ = cdata; tcx.calculate_dtor(def_id, |_,_| Ok(())) } + adt_async_destructor => { + let _ = cdata; + tcx.calculate_async_dtor(def_id, |_,_| Ok(())) + } associated_item_def_ids => { tcx.arena.alloc_from_iter(cdata.get_associated_item_or_field_def_ids(def_id.index)) } diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs index 1e36f034cc2..f98dbf8a0bd 100644 --- a/compiler/rustc_middle/src/query/erase.rs +++ b/compiler/rustc_middle/src/query/erase.rs @@ -238,6 +238,7 @@ impl EraseType for $ty { Option, Option, Option, + Option, Option, Option, Option, @@ -295,6 +296,7 @@ impl EraseType for $ty { rustc_middle::ty::AssocItem, rustc_middle::ty::AssocItemContainer, rustc_middle::ty::Asyncness, + rustc_middle::ty::AsyncDestructor, rustc_middle::ty::BoundVariableKind, rustc_middle::ty::DeducedParamAttrs, rustc_middle::ty::Destructor, diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs index 6ad4b7c40fb..d72ad09f954 100644 --- a/compiler/rustc_middle/src/query/mod.rs +++ b/compiler/rustc_middle/src/query/mod.rs @@ -703,6 +703,11 @@ cache_on_disk_if { key.is_local() } separate_provide_extern } + query adt_async_destructor(key: DefId) -> Option { + desc { |tcx| "computing `AsyncDrop` impl for `{}`", tcx.def_path_str(key) } + cache_on_disk_if { key.is_local() } + separate_provide_extern + } query adt_sized_constraint(key: DefId) -> Option>> { desc { |tcx| "computing the `Sized` constraint for `{}`", tcx.def_path_str(key) } @@ -1343,18 +1348,14 @@ query is_unpin_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { desc { "computing whether `{}` is `Unpin`", env.value } } - /// Query backing `Ty::has_surface_async_drop`. - query has_surface_async_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { - desc { "computing whether `{}` has `AsyncDrop` implementation", env.value } - } - /// Query backing `Ty::has_surface_drop`. - query has_surface_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { - desc { "computing whether `{}` has `Drop` implementation", env.value } - } /// Query backing `Ty::needs_drop`. query needs_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { desc { "computing whether `{}` needs drop", env.value } } + /// Query backing `Ty::needs_async_drop`. + query needs_async_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + desc { "computing whether `{}` needs async drop", env.value } + } /// Query backing `Ty::has_significant_drop_raw`. query has_significant_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { desc { "computing whether `{}` has a significant drop", env.value } diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs index 8e946bc8b31..988ce35484d 100644 --- a/compiler/rustc_middle/src/ty/adt.rs +++ b/compiler/rustc_middle/src/ty/adt.rs @@ -24,7 +24,9 @@ use std::ops::Range; use std::str; -use super::{Destructor, FieldDef, GenericPredicates, Ty, TyCtxt, VariantDef, VariantDiscr}; +use super::{ + AsyncDestructor, Destructor, FieldDef, GenericPredicates, Ty, TyCtxt, VariantDef, VariantDiscr, +}; #[derive(Clone, Copy, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)] pub struct AdtFlags(u16); @@ -577,6 +579,12 @@ pub fn destructor(self, tcx: TyCtxt<'tcx>) -> Option { tcx.adt_destructor(self.did()) } + // FIXME(zetanumbers): consider supporting this method in same places where + // `destructor` is referenced + pub fn async_destructor(self, tcx: TyCtxt<'tcx>) -> Option { + tcx.adt_async_destructor(self.did()) + } + /// Returns a type such that `Self: Sized` if and only if that type is `Sized`, /// or `None` if the type is always sized. pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> Option>> { diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs index f24074cb472..90c154233da 100644 --- a/compiler/rustc_middle/src/ty/mod.rs +++ b/compiler/rustc_middle/src/ty/mod.rs @@ -1172,6 +1172,15 @@ pub struct Destructor { pub constness: hir::Constness, } +// FIXME: consider combining this definition with regular `Destructor` +#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)] +pub struct AsyncDestructor { + /// The `DefId` of the async destructor future constructor + pub ctor: DefId, + /// The `DefId` of the async destructor future type + pub future: DefId, +} + #[derive(Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)] pub struct VariantFlags(u8); bitflags::bitflags! { diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index 5cf96d29837..00f603a8818 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -1991,7 +1991,7 @@ pub fn async_destructor_ty(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) - ty::Adt(adt_def, _) => { assert!(adt_def.is_union()); - let surface_drop = self.surface_async_dropper_ty(tcx, param_env).unwrap(); + let surface_drop = self.surface_async_dropper_ty(tcx).unwrap(); Ty::async_destructor_combinator(tcx, LangItem::AsyncDropFuse) .instantiate(tcx, &[surface_drop.into()]) @@ -2041,7 +2041,7 @@ fn adt_async_destructor_ty( }) .unwrap(); - let dtor = if let Some(dropper_ty) = self.surface_async_dropper_ty(tcx, param_env) { + let dtor = if let Some(dropper_ty) = self.surface_async_dropper_ty(tcx) { Ty::async_destructor_combinator(tcx, LangItem::AsyncDropChain) .instantiate(tcx, &[dropper_ty.into(), variants_dtor.into()]) } else { @@ -2052,21 +2052,13 @@ fn adt_async_destructor_ty( .instantiate(tcx, &[dtor.into()]) } - fn surface_async_dropper_ty( - self, - tcx: TyCtxt<'tcx>, - param_env: ParamEnv<'tcx>, - ) -> Option> { - if self.has_surface_async_drop(tcx, param_env) { - Some(LangItem::SurfaceAsyncDropInPlace) - } else if self.has_surface_drop(tcx, param_env) { - Some(LangItem::AsyncDropSurfaceDropInPlace) - } else { - None - } - .map(|dropper| { - Ty::async_destructor_combinator(tcx, dropper).instantiate(tcx, &[self.into()]) - }) + fn surface_async_dropper_ty(self, tcx: TyCtxt<'tcx>) -> Option> { + let adt_def = self.ty_adt_def()?; + let dropper = adt_def + .async_destructor(tcx) + .map(|_| LangItem::SurfaceAsyncDropInPlace) + .or_else(|| adt_def.destructor(tcx).map(|_| LangItem::AsyncDropSurfaceDropInPlace))?; + Some(Ty::async_destructor_combinator(tcx, dropper).instantiate(tcx, &[self.into()])) } fn async_destructor_combinator( diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs index cacaa859d52..905ada3832d 100644 --- a/compiler/rustc_middle/src/ty/util.rs +++ b/compiler/rustc_middle/src/ty/util.rs @@ -4,8 +4,8 @@ use crate::query::{IntoQueryParam, Providers}; use crate::ty::layout::{FloatExt, IntegerExt}; use crate::ty::{ - self, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, - TypeVisitableExt, Upcast, + self, Asyncness, FallibleTypeFolder, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, + TypeSuperFoldable, TypeVisitableExt, Upcast, }; use crate::ty::{GenericArgKind, GenericArgsRef}; use rustc_apfloat::Float as _; @@ -382,6 +382,45 @@ pub fn calculate_dtor( Some(ty::Destructor { did, constness }) } + /// Calculate the async destructor of a given type. + pub fn calculate_async_dtor( + self, + adt_did: DefId, + validate: impl Fn(Self, DefId) -> Result<(), ErrorGuaranteed>, + ) -> Option { + let async_drop_trait = self.lang_items().async_drop_trait()?; + self.ensure().coherent_trait(async_drop_trait).ok()?; + + let ty = self.type_of(adt_did).instantiate_identity(); + let mut dtor_candidate = None; + self.for_each_relevant_impl(async_drop_trait, ty, |impl_did| { + if validate(self, impl_did).is_err() { + // Already `ErrorGuaranteed`, no need to delay a span bug here. + return; + } + + let [future, ctor] = self.associated_item_def_ids(impl_did) else { + self.dcx().span_delayed_bug( + self.def_span(impl_did), + "AsyncDrop impl without async_drop function or Dropper type", + ); + return; + }; + + if let Some((_, _, old_impl_did)) = dtor_candidate { + self.dcx() + .struct_span_err(self.def_span(impl_did), "multiple async drop impls found") + .with_span_note(self.def_span(old_impl_did), "other impl here") + .delay_as_bug(); + } + + dtor_candidate = Some((*future, *ctor, impl_did)); + }); + + let (future, ctor, _) = dtor_candidate?; + Some(ty::AsyncDestructor { future, ctor }) + } + /// Returns the set of types that are required to be alive in /// order to run the destructor of `def` (see RFCs 769 and /// 1238). @@ -1303,72 +1342,19 @@ fn is_trivially_unpin(self) -> bool { } } - /// Checks whether values of this type `T` implements the `AsyncDrop` - /// trait. - pub fn has_surface_async_drop(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { - self.could_have_surface_async_drop() && tcx.has_surface_async_drop_raw(param_env.and(self)) - } - - /// Fast path helper for testing if a type has `AsyncDrop` - /// implementation. - /// - /// Returning `false` means the type is known to not have `AsyncDrop` - /// implementation. Returning `true` means nothing -- could be - /// `AsyncDrop`, might not be. - fn could_have_surface_async_drop(self) -> bool { - !self.is_async_destructor_trivially_noop() - && !matches!( - self.kind(), - ty::Tuple(_) - | ty::Slice(_) - | ty::Array(_, _) - | ty::Closure(..) - | ty::CoroutineClosure(..) - | ty::Coroutine(..) - ) - } - - /// Checks whether values of this type `T` implements the `Drop` - /// trait. - pub fn has_surface_drop(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { - self.could_have_surface_drop() && tcx.has_surface_drop_raw(param_env.and(self)) - } - - /// Fast path helper for testing if a type has `Drop` implementation. - /// - /// Returning `false` means the type is known to not have `Drop` - /// implementation. Returning `true` means nothing -- could be - /// `Drop`, might not be. - fn could_have_surface_drop(self) -> bool { - !self.is_async_destructor_trivially_noop() - && !matches!( - self.kind(), - ty::Tuple(_) - | ty::Slice(_) - | ty::Array(_, _) - | ty::Closure(..) - | ty::CoroutineClosure(..) - | ty::Coroutine(..) - ) - } - /// Checks whether values of this type `T` implement has noop async destructor. // // FIXME: implement optimization to make ADTs, which do not need drop, - // to skip fields or to have noop async destructor. + // to skip fields or to have noop async destructor, use `needs_(async_)drop` pub fn is_async_destructor_noop( self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ) -> bool { + // TODO: check on the most generic version of your type self.is_async_destructor_trivially_noop() - || if let ty::Adt(adt_def, _) = self.kind() { - (adt_def.is_union() || adt_def.is_payloadfree()) - && !self.has_surface_async_drop(tcx, param_env) - && !self.has_surface_drop(tcx, param_env) - } else { - false - } + || self.needs_async_drop(tcx, param_env) + || self.needs_drop(tcx, param_env) } /// Fast path helper for testing if a type has noop async destructor. @@ -1391,7 +1377,34 @@ fn is_async_destructor_trivially_noop(self) -> bool { | ty::FnPtr(_) => true, ty::Tuple(tys) => tys.is_empty(), ty::Adt(adt_def, _) => adt_def.is_manually_drop(), - _ => false, + ty::Bool => todo!(), + ty::Char => todo!(), + ty::Int(_) => todo!(), + ty::Uint(_) => todo!(), + ty::Float(_) => todo!(), + ty::Adt(_, _) => todo!(), + ty::Foreign(_) => todo!(), + ty::Str => todo!(), + ty::Array(_, _) => todo!(), + ty::Pat(_, _) => todo!(), + ty::Slice(_) => todo!(), + ty::RawPtr(_, _) => todo!(), + ty::Ref(_, _, _) => todo!(), + ty::FnDef(_, _) => todo!(), + ty::FnPtr(_) => todo!(), + ty::Dynamic(_, _, _) => todo!(), + ty::Closure(_, _) => todo!(), + ty::CoroutineClosure(_, _) => todo!(), + ty::Coroutine(_, _) => todo!(), + ty::CoroutineWitness(_, _) => todo!(), + ty::Never => todo!(), + ty::Tuple(_) => todo!(), + ty::Alias(_, _) => todo!(), + ty::Param(_) => todo!(), + ty::Bound(_, _) => todo!(), + ty::Placeholder(_) => todo!(), + ty::Infer(_) => todo!(), + ty::Error(_) => todo!(), } } @@ -1430,6 +1443,42 @@ pub fn needs_drop(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> boo } } + /// If `ty.needs_async_drop(...)` returns `true`, then `ty` is definitely + /// non-copy and *might* have a async destructor attached; if it returns + /// `false`, then `ty` definitely has no async destructor (i.e., no async + /// drop glue). + /// + /// (Note that this implies that if `ty` has an async destructor attached, + /// then `needs_async_drop` will definitely return `true` for `ty`.) + /// + /// Note that this method is used to check eligible types in unions. + #[inline] + pub fn needs_async_drop(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { + // Avoid querying in simple cases. + match needs_drop_components(tcx, self) { + Err(AlwaysRequiresDrop) => true, + Ok(components) => { + let query_ty = match *components { + [] => return false, + // If we've got a single component, call the query with that + // to increase the chance that we hit the query cache. + [component_ty] => component_ty, + _ => self, + }; + + // This doesn't depend on regions, so try to minimize distinct + // query keys used. + // If normalization fails, we just use `query_ty`. + debug_assert!(!param_env.has_infer()); + let query_ty = tcx + .try_normalize_erasing_regions(param_env, query_ty) + .unwrap_or_else(|_| tcx.erase_regions(query_ty)); + + tcx.needs_async_drop_raw(param_env.and(query_ty)) + } + } + } + /// Checks if `ty` has a significant drop. /// /// Note that this method can return false even if `ty` has a destructor @@ -1598,12 +1647,24 @@ pub fn determine

(self_arg_ty: Ty<'tcx>, is_self_ty: P) -> ExplicitSelf<'tcx> } } +// FIXME(zetanumbers): make specifying asyncness explicit /// Returns a list of types such that the given type needs drop if and only if /// *any* of the returned types need drop. Returns `Err(AlwaysRequiresDrop)` if /// this type always needs drop. pub fn needs_drop_components<'tcx>( tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, +) -> Result; 2]>, AlwaysRequiresDrop> { + needs_drop_components_with_async(tcx, ty, Asyncness::No) +} + +/// Returns a list of types such that the given type needs drop if and only if +/// *any* of the returned types need drop. Returns `Err(AlwaysRequiresDrop)` if +/// this type always needs drop. +pub fn needs_drop_components_with_async<'tcx>( + tcx: TyCtxt<'tcx>, + ty: Ty<'tcx>, + asyncness: Asyncness, ) -> Result; 2]>, AlwaysRequiresDrop> { match *ty.kind() { ty::Infer(ty::FreshIntTy(_)) @@ -1623,11 +1684,18 @@ pub fn needs_drop_components<'tcx>( // Foreign types can never have destructors. ty::Foreign(..) => Ok(SmallVec::new()), - ty::Dynamic(..) | ty::Error(_) => Err(AlwaysRequiresDrop), + // FIXME(zetanumbers): Temporary workaround for async drop of dynamic types + ty::Dynamic(..) | ty::Error(_) => { + if asyncness.is_async() { + Ok(SmallVec::new()) + } else { + Err(AlwaysRequiresDrop) + } + } - ty::Pat(ty, _) | ty::Slice(ty) => needs_drop_components(tcx, ty), + ty::Pat(ty, _) | ty::Slice(ty) => needs_drop_components_with_async(tcx, ty, asyncness), ty::Array(elem_ty, size) => { - match needs_drop_components(tcx, elem_ty) { + match needs_drop_components_with_async(tcx, elem_ty, asyncness) { Ok(v) if v.is_empty() => Ok(v), res => match size.try_to_target_usize(tcx) { // Arrays of size zero don't need drop, even if their element @@ -1643,7 +1711,7 @@ pub fn needs_drop_components<'tcx>( } // If any field needs drop, then the whole tuple does. ty::Tuple(fields) => fields.iter().try_fold(SmallVec::new(), move |mut acc, elem| { - acc.extend(needs_drop_components(tcx, elem)?); + acc.extend(needs_drop_components_with_async(tcx, elem, asyncness)?); Ok(acc) }), diff --git a/compiler/rustc_ty_utils/src/common_traits.rs b/compiler/rustc_ty_utils/src/common_traits.rs index cb95239e991..51b908881eb 100644 --- a/compiler/rustc_ty_utils/src/common_traits.rs +++ b/compiler/rustc_ty_utils/src/common_traits.rs @@ -22,17 +22,6 @@ fn is_unpin_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) is_item_raw(tcx, query, LangItem::Unpin) } -fn has_surface_async_drop_raw<'tcx>( - tcx: TyCtxt<'tcx>, - query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, -) -> bool { - is_item_raw(tcx, query, LangItem::AsyncDrop) -} - -fn has_surface_drop_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { - is_item_raw(tcx, query, LangItem::Drop) -} - fn is_item_raw<'tcx>( tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, @@ -45,13 +34,5 @@ fn is_item_raw<'tcx>( } pub(crate) fn provide(providers: &mut Providers) { - *providers = Providers { - is_copy_raw, - is_sized_raw, - is_freeze_raw, - is_unpin_raw, - has_surface_async_drop_raw, - has_surface_drop_raw, - ..*providers - }; + *providers = Providers { is_copy_raw, is_sized_raw, is_freeze_raw, is_unpin_raw, ..*providers }; } diff --git a/compiler/rustc_ty_utils/src/needs_drop.rs b/compiler/rustc_ty_utils/src/needs_drop.rs index 72ee1a48249..7fc3543ff66 100644 --- a/compiler/rustc_ty_utils/src/needs_drop.rs +++ b/compiler/rustc_ty_utils/src/needs_drop.rs @@ -30,6 +30,21 @@ fn needs_drop_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx> res } +fn needs_async_drop_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool { + // If we don't know a type doesn't need async drop, for example if it's a + // type parameter without a `Copy` bound, then we conservatively return that + // it needs async drop. + let adt_has_async_dtor = + |adt_def: ty::AdtDef<'tcx>| adt_def.async_destructor(tcx).map(|_| DtorType::Significant); + let res = drop_tys_helper(tcx, query.value, query.param_env, adt_has_dtor, false) + .filter(filter_array_elements(tcx, query.param_env)) + .next() + .is_some(); + + debug!("needs_drop_raw({:?}) = {:?}", query, res); + res +} + /// HACK: in order to not mistakenly assume that `[PhantomData; N]` requires drop glue /// we check the element type for drop glue. The correct fix would be looking at the /// entirety of the code around `needs_drop_components` and this file and come up with @@ -389,6 +404,7 @@ fn adt_significant_drop_tys( pub(crate) fn provide(providers: &mut Providers) { *providers = Providers { needs_drop_raw, + needs_async_drop_raw, has_significant_drop_raw, adt_drop_tys, adt_significant_drop_tys,