//! Code shared by trait and projection goals for candidate assembly.
use super::infcx_ext::InferCtxtExt;
-use super::{CanonicalResponse, Certainty, EvalCtxt, Goal};
+use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, QueryResult};
use rustc_hir::def_id::DefId;
use rustc_infer::traits::query::NoSolution;
+use rustc_infer::traits::util::elaborate_predicates;
use rustc_middle::ty::TypeFoldable;
use rustc_middle::ty::{self, Ty, TyCtxt};
use std::fmt::Debug;
AliasBound(usize),
}
-pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
+pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq {
fn self_ty(self) -> Ty<'tcx>;
fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self;
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
impl_def_id: DefId,
- ) -> Result<Certainty, NoSolution>;
+ ) -> QueryResult<'tcx>;
+
+ fn consider_assumption(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ assumption: ty::Predicate<'tcx>,
+ ) -> QueryResult<'tcx>;
+
+ fn consider_auto_trait_candidate(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ ) -> QueryResult<'tcx>;
+
+ fn consider_trait_alias_candidate(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ ) -> QueryResult<'tcx>;
fn consider_builtin_sized_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
- ) -> Result<Certainty, NoSolution>;
+ ) -> QueryResult<'tcx>;
- fn consider_assumption(
+ fn consider_builtin_copy_clone_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
- assumption: ty::Predicate<'tcx>,
- ) -> Result<Certainty, NoSolution>;
+ ) -> QueryResult<'tcx>;
+
+ fn consider_builtin_pointer_sized_candidate(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ ) -> QueryResult<'tcx>;
+
+ fn consider_builtin_fn_trait_candidates(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ kind: ty::ClosureKind,
+ ) -> QueryResult<'tcx>;
+
+ fn consider_builtin_tuple_candidate(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ ) -> QueryResult<'tcx>;
+
+ fn consider_builtin_pointee_candidate(
+ ecx: &mut EvalCtxt<'_, 'tcx>,
+ goal: Goal<'tcx, Self>,
+ ) -> QueryResult<'tcx>;
}
+
impl<'tcx> EvalCtxt<'_, 'tcx> {
pub(super) fn assemble_and_evaluate_candidates<G: GoalKind<'tcx>>(
&mut self,
goal: Goal<'tcx, G>,
) -> Vec<Candidate<'tcx>> {
+ debug_assert_eq!(goal, self.infcx.resolve_vars_if_possible(goal));
+
+ // HACK: `_: Trait` is ambiguous, because it may be satisfied via a builtin rule,
+ // object bound, alias bound, etc. We are unable to determine this until we can at
+ // least structually resolve the type one layer.
+ if goal.predicate.self_ty().is_ty_var() {
+ return vec![Candidate {
+ source: CandidateSource::BuiltinImpl,
+ result: self.make_canonical_response(Certainty::AMBIGUOUS).unwrap(),
+ }];
+ }
+
let mut candidates = Vec::new();
self.assemble_candidates_after_normalizing_self_ty(goal, &mut candidates);
self.assemble_alias_bound_candidates(goal, &mut candidates);
+ self.assemble_object_bound_candidates(goal, &mut candidates);
+
candidates
}
Ok((_, certainty)) => certainty,
Err(NoSolution) => return,
};
+ let normalized_ty = self.infcx.resolve_vars_if_possible(normalized_ty);
// NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
// This doesn't work as long as we use `CandidateSource` in winnowing.
tcx.for_each_relevant_impl(
goal.predicate.trait_def_id(tcx),
goal.predicate.self_ty(),
- |impl_def_id| match G::consider_impl_candidate(self, goal, impl_def_id)
- .and_then(|certainty| self.make_canonical_response(certainty))
- {
+ |impl_def_id| match G::consider_impl_candidate(self, goal, impl_def_id) {
Ok(result) => candidates
.push(Candidate { source: CandidateSource::Impl(impl_def_id), result }),
Err(NoSolution) => (),
) {
let lang_items = self.tcx().lang_items();
let trait_def_id = goal.predicate.trait_def_id(self.tcx());
- let result = if lang_items.sized_trait() == Some(trait_def_id) {
+ let result = if self.tcx().trait_is_auto(trait_def_id) {
+ G::consider_auto_trait_candidate(self, goal)
+ } else if self.tcx().trait_is_alias(trait_def_id) {
+ G::consider_trait_alias_candidate(self, goal)
+ } else if lang_items.sized_trait() == Some(trait_def_id) {
G::consider_builtin_sized_candidate(self, goal)
+ } else if lang_items.copy_trait() == Some(trait_def_id)
+ || lang_items.clone_trait() == Some(trait_def_id)
+ {
+ G::consider_builtin_copy_clone_candidate(self, goal)
+ } else if lang_items.pointer_sized() == Some(trait_def_id) {
+ G::consider_builtin_pointer_sized_candidate(self, goal)
+ } else if let Some(kind) = self.tcx().fn_trait_kind_from_def_id(trait_def_id) {
+ G::consider_builtin_fn_trait_candidates(self, goal, kind)
+ } else if lang_items.tuple_trait() == Some(trait_def_id) {
+ G::consider_builtin_tuple_candidate(self, goal)
+ } else if lang_items.pointee_trait() == Some(trait_def_id) {
+ G::consider_builtin_pointee_candidate(self, goal)
} else {
Err(NoSolution)
};
- match result.and_then(|certainty| self.make_canonical_response(certainty)) {
+ match result {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::BuiltinImpl, result })
}
candidates: &mut Vec<Candidate<'tcx>>,
) {
for (i, assumption) in goal.param_env.caller_bounds().iter().enumerate() {
- match G::consider_assumption(self, goal, assumption)
- .and_then(|certainty| self.make_canonical_response(certainty))
- {
+ match G::consider_assumption(self, goal, assumption) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::ParamEnv(i), result })
}
.subst_iter_copied(self.tcx(), alias_ty.substs)
.enumerate()
{
- match G::consider_assumption(self, goal, assumption)
- .and_then(|certainty| self.make_canonical_response(certainty))
- {
+ match G::consider_assumption(self, goal, assumption) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::AliasBound(i), result })
}
}
}
}
+
+ fn assemble_object_bound_candidates<G: GoalKind<'tcx>>(
+ &mut self,
+ goal: Goal<'tcx, G>,
+ candidates: &mut Vec<Candidate<'tcx>>,
+ ) {
+ let self_ty = goal.predicate.self_ty();
+ let bounds = match *self_ty.kind() {
+ ty::Bool
+ | ty::Char
+ | ty::Int(_)
+ | ty::Uint(_)
+ | ty::Float(_)
+ | ty::Adt(_, _)
+ | ty::Foreign(_)
+ | ty::Str
+ | ty::Array(_, _)
+ | ty::Slice(_)
+ | ty::RawPtr(_)
+ | ty::Ref(_, _, _)
+ | ty::FnDef(_, _)
+ | ty::FnPtr(_)
+ | ty::Alias(..)
+ | ty::Closure(..)
+ | ty::Generator(..)
+ | ty::GeneratorWitness(_)
+ | ty::Never
+ | ty::Tuple(_)
+ | ty::Param(_)
+ | ty::Placeholder(..)
+ | ty::Infer(_)
+ | ty::Error(_) => return,
+ ty::Bound(..) => bug!("unexpected bound type: {goal:?}"),
+ ty::Dynamic(bounds, ..) => bounds,
+ };
+
+ let tcx = self.tcx();
+ for assumption in
+ elaborate_predicates(tcx, bounds.iter().map(|bound| bound.with_self_ty(tcx, self_ty)))
+ {
+ match G::consider_assumption(self, goal, assumption.predicate) {
+ Ok(result) => {
+ candidates.push(Candidate { source: CandidateSource::BuiltinImpl, result })
+ }
+ Err(NoSolution) => (),
+ }
+ }
+ }
}
projects / rust.git / blobdiff