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Consolidate logic around resolving built-in coroutine trait impls

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This commit is contained in:
Michael Goulet 2024-01-19 21:28:37 +00:00
parent 32ec40c685
commit f2ef88ba06
5 changed files with 56 additions and 58 deletions
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3
compiler/rustc_hir/src/lang_items.rs
View File

@ -213,8 +213,11 @@ language_item_table! {
Iterator, sym::iterator, iterator_trait, Target::Trait, GenericRequirement::Exact(0);
Future, sym::future_trait, future_trait, Target::Trait, GenericRequirement::Exact(0);
AsyncIterator, sym::async_iterator, async_iterator_trait, Target::Trait, GenericRequirement::Exact(0);
CoroutineState, sym::coroutine_state, coroutine_state, Target::Enum, GenericRequirement::None;
Coroutine, sym::coroutine, coroutine_trait, Target::Trait, GenericRequirement::Minimum(1);
CoroutineResume, sym::coroutine_resume, coroutine_resume, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
Unpin, sym::unpin, unpin_trait, Target::Trait, GenericRequirement::None;
Pin, sym::pin, pin_type, Target::Struct, GenericRequirement::None;

50
compiler/rustc_middle/src/ty/instance.rs
View File

@ -3,6 +3,7 @@ use crate::ty::print::{FmtPrinter, Printer};
use crate::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
use crate::ty::{EarlyBinder, GenericArgs, GenericArgsRef, TypeVisitableExt};
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_hir::def::Namespace;
use rustc_hir::def_id::{CrateNum, DefId};
use rustc_hir::lang_items::LangItem;
@ -11,6 +12,7 @@ use rustc_macros::HashStable;
use rustc_middle::ty::normalize_erasing_regions::NormalizationError;
use rustc_span::Symbol;
use std::assert_matches::assert_matches;
use std::fmt;
/// A monomorphized `InstanceDef`.
@ -572,6 +574,54 @@ impl<'tcx> Instance<'tcx> {
Some(Instance { def, args })
}
pub fn try_resolve_item_for_coroutine(
tcx: TyCtxt<'tcx>,
trait_item_id: DefId,
trait_id: DefId,
rcvr_args: ty::GenericArgsRef<'tcx>,
) -> Option<Instance<'tcx>> {
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
return None;
};
let coroutine_kind = tcx.coroutine_kind(coroutine_def_id).unwrap();
let lang_items = tcx.lang_items();
let coroutine_callable_item = if Some(trait_id) == lang_items.future_trait() {
assert_matches!(
coroutine_kind,
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)
);
hir::LangItem::FuturePoll
} else if Some(trait_id) == lang_items.iterator_trait() {
assert_matches!(
coroutine_kind,
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)
);
hir::LangItem::IteratorNext
} else if Some(trait_id) == lang_items.async_iterator_trait() {
assert_matches!(
coroutine_kind,
hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)
);
hir::LangItem::AsyncIteratorPollNext
} else if Some(trait_id) == lang_items.coroutine_trait() {
assert_matches!(coroutine_kind, hir::CoroutineKind::Coroutine(_));
hir::LangItem::CoroutineResume
} else {
return None;
};
if tcx.lang_items().get(coroutine_callable_item) == Some(trait_item_id) {
Some(Instance { def: ty::InstanceDef::Item(coroutine_def_id), args: args })
} else {
// All other methods should be defaulted methods of the built-in trait.
// This is important for `Iterator`'s combinators, but also useful for
// adding future default methods to `Future`, for instance.
debug_assert!(tcx.defaultness(trait_item_id).has_value());
Some(Instance::new(trait_item_id, rcvr_args))
}
}
/// Depending on the kind of `InstanceDef`, the MIR body associated with an
/// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other
/// cases the MIR body is expressed in terms of the types found in the substitution array.

1
compiler/rustc_span/src/symbol.rs
View File

@ -600,6 +600,7 @@ symbols! {
core_panic_macro,
coroutine,
coroutine_clone,
coroutine_resume,
coroutine_state,
coroutines,
cosf32,

59
compiler/rustc_ty_utils/src/instance.rs
View File

@ -245,63 +245,6 @@ fn resolve_associated_item<'tcx>(
span: tcx.def_span(trait_item_id),
})
}
} else if Some(trait_ref.def_id) == lang_items.future_trait() {
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
bug!()
};
if Some(trait_item_id) == tcx.lang_items().future_poll_fn() {
// `Future::poll` is generated by the compiler.
Some(Instance { def: ty::InstanceDef::Item(coroutine_def_id), args: args })
} else {
// All other methods are default methods of the `Future` trait.
// (this assumes that `ImplSource::Builtin` is only used for methods on `Future`)
debug_assert!(tcx.defaultness(trait_item_id).has_value());
Some(Instance::new(trait_item_id, rcvr_args))
}
} else if Some(trait_ref.def_id) == lang_items.iterator_trait() {
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
bug!()
};
if Some(trait_item_id) == tcx.lang_items().next_fn() {
// `Iterator::next` is generated by the compiler.
Some(Instance { def: ty::InstanceDef::Item(coroutine_def_id), args })
} else {
// All other methods are default methods of the `Iterator` trait.
// (this assumes that `ImplSource::Builtin` is only used for methods on `Iterator`)
debug_assert!(tcx.defaultness(trait_item_id).has_value());
Some(Instance::new(trait_item_id, rcvr_args))
}
} else if Some(trait_ref.def_id) == lang_items.async_iterator_trait() {
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
bug!()
};
if cfg!(debug_assertions) && tcx.item_name(trait_item_id) != sym::poll_next {
span_bug!(
tcx.def_span(coroutine_def_id),
"no definition for `{trait_ref}::{}` for built-in coroutine type",
tcx.item_name(trait_item_id)
)
}
// `AsyncIterator::poll_next` is generated by the compiler.
Some(Instance { def: ty::InstanceDef::Item(coroutine_def_id), args })
} else if Some(trait_ref.def_id) == lang_items.coroutine_trait() {
let ty::Coroutine(coroutine_def_id, args) = *rcvr_args.type_at(0).kind() else {
bug!()
};
if cfg!(debug_assertions) && tcx.item_name(trait_item_id) != sym::resume {
// For compiler developers who'd like to add new items to `Coroutine`,
// you either need to generate a shim body, or perhaps return
// `InstanceDef::Item` pointing to a trait default method body if
// it is given a default implementation by the trait.
span_bug!(
tcx.def_span(coroutine_def_id),
"no definition for `{trait_ref}::{}` for built-in coroutine type",
tcx.item_name(trait_item_id)
)
}
Some(Instance { def: ty::InstanceDef::Item(coroutine_def_id), args })
} else if tcx.fn_trait_kind_from_def_id(trait_ref.def_id).is_some() {
// FIXME: This doesn't check for malformed libcore that defines, e.g.,
// `trait Fn { fn call_once(&self) { .. } }`. This is mostly for extension
@ -334,7 +277,7 @@ fn resolve_associated_item<'tcx>(
),
}
} else {
None
Instance::try_resolve_item_for_coroutine(tcx, trait_item_id, trait_id, rcvr_args)
}
}
traits::ImplSource::Param(..)

1
library/core/src/ops/coroutine.rs
View File

@ -111,6 +111,7 @@ pub trait Coroutine<R = ()> {
/// been returned previously. While coroutine literals in the language are
/// guaranteed to panic on resuming after `Complete`, this is not guaranteed
/// for all implementations of the `Coroutine` trait.
#[cfg_attr(not(bootstrap), lang = "coroutine_resume")]
fn resume(self: Pin<&mut Self>, arg: R) -> CoroutineState<Self::Yield, Self::Return>;
}