9cba14b95b
the behavior of the type system not only depends on the current assumptions, but also the currentnphase of the compiler. This is mostly necessary as we need to decide whether and how to reveal opaque types. We track this via the `TypingMode`.
76 lines
2.8 KiB
Rust
76 lines
2.8 KiB
Rust
use rustc_data_structures::fx::FxHashSet;
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use rustc_hir::def_id::DefId;
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use rustc_infer::infer::TyCtxtInferExt;
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use rustc_infer::infer::canonical::{Canonical, QueryResponse};
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use rustc_middle::bug;
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use rustc_middle::query::Providers;
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use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
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use rustc_middle::ty::{self, GenericArgs, TyCtxt};
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use rustc_trait_selection::infer::InferCtxtBuilderExt;
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use rustc_trait_selection::traits::query::dropck_outlives::{
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compute_dropck_outlives_inner, dtorck_constraint_for_ty_inner,
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};
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use rustc_trait_selection::traits::query::{CanonicalDropckOutlivesGoal, NoSolution};
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use tracing::debug;
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pub(crate) fn provide(p: &mut Providers) {
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*p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p };
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}
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fn dropck_outlives<'tcx>(
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tcx: TyCtxt<'tcx>,
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canonical_goal: CanonicalDropckOutlivesGoal<'tcx>,
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) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, DropckOutlivesResult<'tcx>>>, NoSolution> {
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debug!("dropck_outlives(goal={:#?})", canonical_goal);
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tcx.infer_ctxt().enter_canonical_trait_query(&canonical_goal, |ocx, goal| {
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compute_dropck_outlives_inner(ocx, goal)
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})
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}
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/// Calculates the dtorck constraint for a type.
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pub(crate) fn adt_dtorck_constraint(
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tcx: TyCtxt<'_>,
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def_id: DefId,
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) -> Result<&DropckConstraint<'_>, NoSolution> {
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let def = tcx.adt_def(def_id);
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let span = tcx.def_span(def_id);
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let typing_env = ty::TypingEnv::non_body_analysis(tcx, def_id);
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debug!("dtorck_constraint: {:?}", def);
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if def.is_manually_drop() {
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bug!("`ManuallyDrop` should have been handled by `trivial_dropck_outlives`");
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} else if def.is_phantom_data() {
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// The first generic parameter here is guaranteed to be a type because it's
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// `PhantomData`.
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let args = GenericArgs::identity_for_item(tcx, def_id);
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assert_eq!(args.len(), 1);
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let result = DropckConstraint {
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outlives: vec![],
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dtorck_types: vec![args.type_at(0)],
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overflows: vec![],
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};
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debug!("dtorck_constraint: {:?} => {:?}", def, result);
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return Ok(tcx.arena.alloc(result));
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}
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let mut result = DropckConstraint::empty();
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for field in def.all_fields() {
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let fty = tcx.type_of(field.did).instantiate_identity();
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dtorck_constraint_for_ty_inner(tcx, typing_env, span, 0, fty, &mut result)?;
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}
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result.outlives.extend(tcx.destructor_constraints(def));
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dedup_dtorck_constraint(&mut result);
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debug!("dtorck_constraint: {:?} => {:?}", def, result);
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Ok(tcx.arena.alloc(result))
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}
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fn dedup_dtorck_constraint(c: &mut DropckConstraint<'_>) {
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let mut outlives = FxHashSet::default();
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let mut dtorck_types = FxHashSet::default();
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c.outlives.retain(|&val| outlives.replace(val).is_none());
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c.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none());
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}
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