69 lines
3.2 KiB
Rust
69 lines
3.2 KiB
Rust
use rustc_middle::traits::query::NoSolution;
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use rustc_middle::traits::solve::{Certainty, Goal, QueryResult};
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use rustc_middle::traits::{ObligationCause, Reveal};
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use rustc_middle::ty;
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use rustc_middle::ty::util::NotUniqueParam;
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use super::{EvalCtxt, SolverMode};
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impl<'tcx> EvalCtxt<'_, 'tcx> {
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pub(super) fn normalize_opaque_type(
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&mut self,
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goal: Goal<'tcx, ty::ProjectionPredicate<'tcx>>,
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) -> QueryResult<'tcx> {
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let tcx = self.tcx();
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let opaque_ty = goal.predicate.projection_ty;
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let expected = goal.predicate.term.ty().expect("no such thing as an opaque const");
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match goal.param_env.reveal() {
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Reveal::UserFacing => match self.solver_mode() {
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SolverMode::Normal => {
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// FIXME: at some point we should call queries without defining
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// new opaque types but having the existing opaque type definitions.
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// This will require moving this below "Prefer opaques registered already".
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if !self.can_define_opaque_ty(opaque_ty.def_id) {
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return Err(NoSolution);
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}
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// FIXME: This may have issues when the substs contain aliases...
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match self.tcx().uses_unique_placeholders_ignoring_regions(opaque_ty.substs) {
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Err(NotUniqueParam::NotParam(param)) if param.is_non_region_infer() => {
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return self.evaluate_added_goals_and_make_canonical_response(
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Certainty::AMBIGUOUS,
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);
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}
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Err(_) => {
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return Err(NoSolution);
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}
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Ok(()) => {}
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}
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// Prefer opaques registered already.
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let matches = self.unify_existing_opaque_tys(
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goal.param_env,
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opaque_ty,
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expected
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);
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if !matches.is_empty() {
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if let Some(response) = self.try_merge_responses(&matches) {
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return Ok(response);
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} else {
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return self.flounder(&matches);
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}
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}
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// Otherwise, define a new opaque type
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let opaque_ty = tcx.mk_opaque(opaque_ty.def_id, opaque_ty.substs);
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self.register_opaque_ty(expected, opaque_ty, goal.param_env)?;
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self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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SolverMode::Coherence => {
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self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
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}
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},
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Reveal::All => {
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// FIXME: Add an assertion that opaque type storage is empty.
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let actual = tcx.type_of(opaque_ty.def_id).subst(tcx, opaque_ty.substs);
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self.eq(goal.param_env, expected, actual)?;
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self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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}
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}
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}
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