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Only compute layout of opaque if coroutine is the cause of an opaque cycle

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This commit is contained in:
Michael Goulet 2023-11-13 02:08:14 +00:00
parent 199af7cef0
commit fa2ff51ace
4 changed files with 53 additions and 12 deletions
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35
compiler/rustc_hir_analysis/src/check/check.rs
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@ -17,7 +17,7 @@ use rustc_middle::middle::stability::EvalResult;
use rustc_middle::traits::{DefiningAnchor, ObligationCauseCode};
use rustc_middle::ty::fold::BottomUpFolder;
use rustc_middle::ty::layout::{LayoutError, MAX_SIMD_LANES};
use rustc_middle::ty::util::{Discr, IntTypeExt};
use rustc_middle::ty::util::{Discr, InspectCoroutineFields, IntTypeExt};
use rustc_middle::ty::GenericArgKind;
use rustc_middle::ty::{
AdtDef, ParamEnv, RegionKind, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
@ -232,16 +232,33 @@ pub(super) fn check_opaque_for_cycles<'tcx>(
span: Span,
) -> Result<(), ErrorGuaranteed> {
let args = GenericArgs::identity_for_item(tcx, def_id);
if tcx.try_expand_impl_trait_type(def_id.to_def_id(), args).is_err() {
let reported = opaque_type_cycle_error(tcx, def_id, span);
Err(reported)
} else if let Err(&LayoutError::Cycle(guar)) =
tcx.layout_of(tcx.param_env(def_id).and(Ty::new_opaque(tcx, def_id.to_def_id(), args)))
// First, try to look at any opaque expansion cycles, considering coroutine fields
// (even though these aren't necessarily true errors).
if tcx
.try_expand_impl_trait_type(def_id.to_def_id(), args, InspectCoroutineFields::Yes)
.is_err()
{
Err(guar)
} else {
Ok(())
// Look for true opaque expansion cycles, but ignore coroutines.
// This will give us any true errors. Coroutines are only problematic
// if they cause layout computation errors.
if tcx
.try_expand_impl_trait_type(def_id.to_def_id(), args, InspectCoroutineFields::No)
.is_err()
{
let reported = opaque_type_cycle_error(tcx, def_id, span);
return Err(reported);
}
// And also look for cycle errors in the layout of coroutines.
if let Err(&LayoutError::Cycle(guar)) =
tcx.layout_of(tcx.param_env(def_id).and(Ty::new_opaque(tcx, def_id.to_def_id(), args)))
{
return Err(guar);
}
}
Ok(())
}
/// Check that the concrete type behind `impl Trait` actually implements `Trait`.