Prereq4 for async drop - needs_async_drop query fixes and some cleanup from previous async drop glue implementation

Author: azhogin

Diff for: compiler/rustc_codegen_cranelift/src/abi/mod.rs

@@ -417,7 +417,9 @@ pub(crate) fn codegen_terminator_call<'tcx>(
                     Err(instance) => Some(instance),
                 }
             }
-            InstanceKind::DropGlue(_, None) | ty::InstanceKind::AsyncDropGlueCtorShim(_, None) => {
+            // We don't need AsyncDropGlueCtorShim here because it is not `noop func`,
+            // it is `func returning noop future`
+            InstanceKind::DropGlue(_, None) => {
                 // empty drop glue - a nop.
                 let dest = target.expect("Non terminating drop_in_place_real???");
                 let ret_block = fx.get_block(dest);
@@ -675,9 +677,8 @@ pub(crate) fn codegen_drop<'tcx>(
     let ty = drop_place.layout().ty;
     let drop_instance = Instance::resolve_drop_in_place(fx.tcx, ty).polymorphize(fx.tcx);
 
-    if let ty::InstanceKind::DropGlue(_, None) | ty::InstanceKind::AsyncDropGlueCtorShim(_, None) =
-        drop_instance.def
-    {
+    // AsyncDropGlueCtorShim can't be here
+    if let ty::InstanceKind::DropGlue(_, None) = drop_instance.def {
         // we don't actually need to drop anything
     } else {
         match ty.kind() {

Diff for: compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -852,10 +852,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
         let def = instance.map(|i| i.def);
 
-        if let Some(
-            ty::InstanceKind::DropGlue(_, None) | ty::InstanceKind::AsyncDropGlueCtorShim(_, None),
-        ) = def
-        {
+        // We don't need AsyncDropGlueCtorShim here because it is not `noop func`,
+        // it is `func returning noop future`
+        if let Some(ty::InstanceKind::DropGlue(_, None)) = def {
             // Empty drop glue; a no-op.
             let target = target.unwrap();
             return helper.funclet_br(self, bx, target, mergeable_succ);

Diff for: compiler/rustc_hir/src/lang_items.rs

@@ -179,20 +179,9 @@ language_item_table! {
 
     Drop,                    sym::drop,                drop_trait,                 Target::Trait,          GenericRequirement::None;
     Destruct,                sym::destruct,            destruct_trait,             Target::Trait,          GenericRequirement::None;
-
-    AsyncDrop,               sym::async_drop,          async_drop_trait,           Target::Trait,          GenericRequirement::Exact(0);
-    AsyncDestruct,           sym::async_destruct,      async_destruct_trait,       Target::Trait,          GenericRequirement::Exact(0);
+    AsyncDrop,               sym::async_drop,          async_drop_trait,           Target::Trait,          GenericRequirement::None;
     AsyncDropInPlace,        sym::async_drop_in_place, async_drop_in_place_fn,     Target::Fn,             GenericRequirement::Exact(1);
     AsyncDropInPlacePoll,    sym::async_drop_in_place_poll, async_drop_in_place_poll_fn, Target::Closure,  GenericRequirement::Exact(1);
-    SurfaceAsyncDropInPlace, sym::surface_async_drop_in_place, surface_async_drop_in_place_fn, Target::Fn, GenericRequirement::Exact(1);
-    AsyncDropSurfaceDropInPlace, sym::async_drop_surface_drop_in_place, async_drop_surface_drop_in_place_fn, Target::Fn, GenericRequirement::Exact(1);
-    AsyncDropSlice,          sym::async_drop_slice,    async_drop_slice_fn,        Target::Fn,             GenericRequirement::Exact(1);
-    AsyncDropChain,          sym::async_drop_chain,    async_drop_chain_fn,        Target::Fn,             GenericRequirement::Exact(2);
-    AsyncDropNoop,           sym::async_drop_noop,     async_drop_noop_fn,         Target::Fn,             GenericRequirement::Exact(0);
-    AsyncDropDeferredDropInPlace, sym::async_drop_deferred_drop_in_place, async_drop_deferred_drop_in_place_fn, Target::Fn, GenericRequirement::Exact(1);
-    AsyncDropFuse,           sym::async_drop_fuse,     async_drop_fuse_fn,         Target::Fn,             GenericRequirement::Exact(1);
-    AsyncDropDefer,          sym::async_drop_defer,    async_drop_defer_fn,        Target::Fn,             GenericRequirement::Exact(1);
-    AsyncDropEither,         sym::async_drop_either,   async_drop_either_fn,       Target::Fn,             GenericRequirement::Exact(3);
 
     CoerceUnsized,           sym::coerce_unsized,      coerce_unsized_trait,       Target::Trait,          GenericRequirement::Minimum(1);
     DispatchFromDyn,         sym::dispatch_from_dyn,   dispatch_from_dyn_trait,    Target::Trait,          GenericRequirement::Minimum(1);
@@ -324,7 +313,6 @@ language_item_table! {
 
     ExchangeMalloc,          sym::exchange_malloc,     exchange_malloc_fn,         Target::Fn,             GenericRequirement::None;
     DropInPlace,             sym::drop_in_place,       drop_in_place_fn,           Target::Fn,             GenericRequirement::Minimum(1);
-    FallbackSurfaceDrop,     sym::fallback_surface_drop, fallback_surface_drop_fn, Target::Fn,             GenericRequirement::None;
     AllocLayout,             sym::alloc_layout,        alloc_layout,               Target::Struct,         GenericRequirement::None;
 
     Start,                   sym::start,               start_fn,                   Target::Fn,             GenericRequirement::Exact(1);

Diff for: compiler/rustc_hir_typeck/src/callee.rs

@@ -35,11 +35,9 @@ pub fn check_legal_trait_for_method_call(
     receiver: Option<Span>,
     expr_span: Span,
     trait_id: DefId,
-    body_id: DefId,
+    _body_id: DefId,
 ) -> Result<(), ErrorGuaranteed> {
-    if tcx.is_lang_item(trait_id, LangItem::Drop)
-        && tcx.lang_items().fallback_surface_drop_fn() != Some(body_id)
-    {
+    if tcx.is_lang_item(trait_id, LangItem::Drop) {
         let sugg = if let Some(receiver) = receiver.filter(|s| !s.is_empty()) {
             errors::ExplicitDestructorCallSugg::Snippet {
                 lo: expr_span.shrink_to_lo(),

Diff for: compiler/rustc_middle/src/query/mod.rs

@@ -1380,6 +1380,10 @@ rustc_queries! {
     query is_unpin_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
         desc { "computing whether `{}` is `Unpin`", env.value }
     }
+    /// Query backing `Ty::is_async_drop`.
+    query is_async_drop_raw(env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
+        desc { "computing whether `{}` is `AsyncDrop`", 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 }
@@ -1412,6 +1416,14 @@ rustc_queries! {
         cache_on_disk_if { true }
     }
 
+    /// A list of types where the ADT requires async drop if and only if any of
+    /// those types require async drop. If the ADT is known to always need async drop
+    /// then `Err(AlwaysRequiresDrop)` is returned.
+    query adt_async_drop_tys(def_id: DefId) -> Result<&'tcx ty::List<Ty<'tcx>>, AlwaysRequiresDrop> {
+        desc { |tcx| "computing when `{}` needs async drop", tcx.def_path_str(def_id) }
+        cache_on_disk_if { true }
+    }
+
     /// A list of types where the ADT requires drop if and only if any of those types
     /// has significant drop. A type marked with the attribute `rustc_insignificant_dtor`
     /// is considered to not be significant. A drop is significant if it is implemented

Diff for: compiler/rustc_middle/src/ty/context.rs

@@ -602,7 +602,6 @@ macro_rules! bidirectional_lang_item_map {
 
 bidirectional_lang_item_map! {
 // tidy-alphabetical-start
-    AsyncDestruct,
     AsyncFn,
     AsyncFnKindHelper,
     AsyncFnKindUpvars,

Diff for: compiler/rustc_middle/src/ty/sty.rs

@@ -4,7 +4,6 @@
 
 use std::assert_matches::debug_assert_matches;
 use std::borrow::Cow;
-use std::iter;
 use std::ops::{ControlFlow, Range};
 
 use hir::def::{CtorKind, DefKind};
@@ -21,7 +20,7 @@ use rustc_target::spec::abi;
 use rustc_type_ir::visit::TypeVisitableExt;
 use rustc_type_ir::TyKind::*;
 use rustc_type_ir::{self as ir, BoundVar, CollectAndApply, DynKind};
-use ty::util::{AsyncDropGlueMorphology, IntTypeExt};
+use ty::util::IntTypeExt;
 
 use super::GenericParamDefKind;
 use crate::infer::canonical::Canonical;
@@ -962,10 +961,6 @@ impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
     fn discriminant_ty(self, interner: TyCtxt<'tcx>) -> Ty<'tcx> {
         self.discriminant_ty(interner)
     }
-
-    fn async_destructor_ty(self, interner: TyCtxt<'tcx>) -> Ty<'tcx> {
-        self.async_destructor_ty(interner)
-    }
 }
 
 /// Type utilities
@@ -1469,125 +1464,6 @@ impl<'tcx> Ty<'tcx> {
         }
     }
 
-    /// Returns the type of the async destructor of this type.
-    pub fn async_destructor_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
-        match self.async_drop_glue_morphology(tcx) {
-            AsyncDropGlueMorphology::Noop => {
-                return Ty::async_destructor_combinator(tcx, LangItem::AsyncDropNoop)
-                    .instantiate_identity();
-            }
-            AsyncDropGlueMorphology::DeferredDropInPlace => {
-                let drop_in_place =
-                    Ty::async_destructor_combinator(tcx, LangItem::AsyncDropDeferredDropInPlace)
-                        .instantiate(tcx, &[self.into()]);
-                return Ty::async_destructor_combinator(tcx, LangItem::AsyncDropFuse)
-                    .instantiate(tcx, &[drop_in_place.into()]);
-            }
-            AsyncDropGlueMorphology::Custom => (),
-        }
-
-        match *self.kind() {
-            ty::Param(_) | ty::Alias(..) | ty::Infer(ty::TyVar(_)) => {
-                let assoc_items = tcx
-                    .associated_item_def_ids(tcx.require_lang_item(LangItem::AsyncDestruct, None));
-                Ty::new_projection(tcx, assoc_items[0], [self])
-            }
-
-            ty::Array(elem_ty, _) | ty::Slice(elem_ty) => {
-                let dtor = Ty::async_destructor_combinator(tcx, LangItem::AsyncDropSlice)
-                    .instantiate(tcx, &[elem_ty.into()]);
-                Ty::async_destructor_combinator(tcx, LangItem::AsyncDropFuse)
-                    .instantiate(tcx, &[dtor.into()])
-            }
-
-            ty::Adt(adt_def, args) if adt_def.is_enum() || adt_def.is_struct() => self
-                .adt_async_destructor_ty(
-                    tcx,
-                    adt_def.variants().iter().map(|v| v.fields.iter().map(|f| f.ty(tcx, args))),
-                ),
-            ty::Tuple(tys) => self.adt_async_destructor_ty(tcx, iter::once(tys)),
-            ty::Closure(_, args) => {
-                self.adt_async_destructor_ty(tcx, iter::once(args.as_closure().upvar_tys()))
-            }
-            ty::CoroutineClosure(_, args) => self
-                .adt_async_destructor_ty(tcx, iter::once(args.as_coroutine_closure().upvar_tys())),
-
-            ty::Adt(adt_def, _) => {
-                assert!(adt_def.is_union());
-
-                let surface_drop = self.surface_async_dropper_ty(tcx).unwrap();
-
-                Ty::async_destructor_combinator(tcx, LangItem::AsyncDropFuse)
-                    .instantiate(tcx, &[surface_drop.into()])
-            }
-
-            ty::Bound(..)
-            | ty::Foreign(_)
-            | ty::Placeholder(_)
-            | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
-                bug!("`async_destructor_ty` applied to unexpected type: {self:?}")
-            }
-
-            _ => bug!("`async_destructor_ty` is not yet implemented for type: {self:?}"),
-        }
-    }
-
-    fn adt_async_destructor_ty<I>(self, tcx: TyCtxt<'tcx>, variants: I) -> Ty<'tcx>
-    where
-        I: Iterator + ExactSizeIterator,
-        I::Item: IntoIterator<Item = Ty<'tcx>>,
-    {
-        debug_assert_eq!(self.async_drop_glue_morphology(tcx), AsyncDropGlueMorphology::Custom);
-
-        let defer = Ty::async_destructor_combinator(tcx, LangItem::AsyncDropDefer);
-        let chain = Ty::async_destructor_combinator(tcx, LangItem::AsyncDropChain);
-
-        let noop =
-            Ty::async_destructor_combinator(tcx, LangItem::AsyncDropNoop).instantiate_identity();
-        let either = Ty::async_destructor_combinator(tcx, LangItem::AsyncDropEither);
-
-        let variants_dtor = variants
-            .into_iter()
-            .map(|variant| {
-                variant
-                    .into_iter()
-                    .map(|ty| defer.instantiate(tcx, &[ty.into()]))
-                    .reduce(|acc, next| chain.instantiate(tcx, &[acc.into(), next.into()]))
-                    .unwrap_or(noop)
-            })
-            .reduce(|other, matched| {
-                either.instantiate(tcx, &[other.into(), matched.into(), self.into()])
-            })
-            .unwrap();
-
-        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 {
-            variants_dtor
-        };
-
-        Ty::async_destructor_combinator(tcx, LangItem::AsyncDropFuse)
-            .instantiate(tcx, &[dtor.into()])
-    }
-
-    fn surface_async_dropper_ty(self, tcx: TyCtxt<'tcx>) -> Option<Ty<'tcx>> {
-        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(
-        tcx: TyCtxt<'tcx>,
-        lang_item: LangItem,
-    ) -> ty::EarlyBinder<'tcx, Ty<'tcx>> {
-        tcx.fn_sig(tcx.require_lang_item(lang_item, None))
-            .map_bound(|fn_sig| fn_sig.output().no_bound_vars().unwrap())
-    }
-
     /// Returns the type of metadata for (potentially fat) pointers to this type,
     /// or the struct tail if the metadata type cannot be determined.
     pub fn ptr_metadata_ty_or_tail(