use std::cell::RefCell;
use std::fmt::Debug;
use super::FulfillmentContext;
use super::TraitEngine;
use crate::solve::FulfillmentCtxt as NextFulfillmentCtxt;
use crate::traits::error_reporting::TypeErrCtxtExt;
use crate::traits::NormalizeExt;
use rustc_data_structures::fx::FxIndexSet;
use rustc_errors::ErrorGuaranteed;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_infer::infer::at::ToTrace;
use rustc_infer::infer::canonical::{
Canonical, CanonicalQueryResponse, CanonicalVarValues, QueryResponse,
};
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk};
use rustc_infer::traits::{
FulfillmentError, Obligation, ObligationCause, PredicateObligation, TraitEngineExt as _,
};
use rustc_middle::arena::ArenaAllocatable;
use rustc_middle::traits::query::NoSolution;
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::ToPredicate;
use rustc_middle::ty::TypeFoldable;
use rustc_middle::ty::Variance;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_session::config::TraitSolver;
pub trait TraitEngineExt<'tcx> {
fn new(infcx: &InferCtxt<'tcx>) -> Box<Self>;
}
impl<'tcx> TraitEngineExt<'tcx> for dyn TraitEngine<'tcx> {
fn new(infcx: &InferCtxt<'tcx>) -> Box<Self> {
match (infcx.tcx.sess.opts.unstable_opts.trait_solver, infcx.next_trait_solver()) {
(TraitSolver::Classic, false) | (TraitSolver::NextCoherence, false) => {
Box::new(FulfillmentContext::new(infcx))
}
(TraitSolver::Next | TraitSolver::NextCoherence, true) => {
Box::new(NextFulfillmentCtxt::new(infcx))
}
_ => bug!(
"incompatible combination of -Ztrait-solver flag ({:?}) and InferCtxt::next_trait_solver ({:?})",
infcx.tcx.sess.opts.unstable_opts.trait_solver,
infcx.next_trait_solver()
),
}
}
}
pub struct ObligationCtxt<'a, 'tcx> {
pub infcx: &'a InferCtxt<'tcx>,
engine: RefCell<Box<dyn TraitEngine<'tcx>>>,
}
impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
pub fn new(infcx: &'a InferCtxt<'tcx>) -> Self {
Self { infcx, engine: RefCell::new(<dyn TraitEngine<'_>>::new(infcx)) }
}
pub fn register_obligation(&self, obligation: PredicateObligation<'tcx>) {
self.engine.borrow_mut().register_predicate_obligation(self.infcx, obligation);
}
pub fn register_obligations(
&self,
obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
) {
for obligation in obligations {
self.engine.borrow_mut().register_predicate_obligation(self.infcx, obligation)
}
}
pub fn register_infer_ok_obligations<T>(&self, infer_ok: InferOk<'tcx, T>) -> T {
let InferOk { value, obligations } = infer_ok;
self.engine.borrow_mut().register_predicate_obligations(self.infcx, obligations);
value
}
pub fn register_bound(
&self,
cause: ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
def_id: DefId,
) {
let tcx = self.infcx.tcx;
let trait_ref = ty::TraitRef::new(tcx, def_id, [ty]);
self.register_obligation(Obligation {
cause,
recursion_depth: 0,
param_env,
predicate: ty::Binder::dummy(trait_ref).to_predicate(tcx),
});
}
pub fn normalize<T: TypeFoldable<TyCtxt<'tcx>>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> T {
let infer_ok = self.infcx.at(&cause, param_env).normalize(value);
self.register_infer_ok_obligations(infer_ok)
}
pub fn eq_exp<T>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
a_is_expected: bool,
a: T,
b: T,
) -> Result<(), TypeError<'tcx>>
where
T: ToTrace<'tcx>,
{
self.infcx
.at(cause, param_env)
.eq_exp(DefineOpaqueTypes::Yes, a_is_expected, a, b)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
pub fn eq<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
self.infcx
.at(cause, param_env)
.eq(DefineOpaqueTypes::Yes, expected, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
pub fn sub<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
self.infcx
.at(cause, param_env)
.sub(DefineOpaqueTypes::Yes, expected, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
pub fn relate<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
variance: Variance,
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
self.infcx
.at(cause, param_env)
.relate(DefineOpaqueTypes::Yes, expected, variance, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
pub fn sup<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
self.infcx
.at(cause, param_env)
.sup(DefineOpaqueTypes::Yes, expected, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
#[must_use]
pub fn select_where_possible(&self) -> Vec<FulfillmentError<'tcx>> {
self.engine.borrow_mut().select_where_possible(self.infcx)
}
#[must_use]
pub fn select_all_or_error(&self) -> Vec<FulfillmentError<'tcx>> {
self.engine.borrow_mut().select_all_or_error(self.infcx)
}
pub fn resolve_regions_and_report_errors(
self,
generic_param_scope: LocalDefId,
outlives_env: &OutlivesEnvironment<'tcx>,
) -> Result<(), ErrorGuaranteed> {
let errors = self.infcx.resolve_regions(&outlives_env);
if errors.is_empty() {
Ok(())
} else {
Err(self.infcx.err_ctxt().report_region_errors(generic_param_scope, &errors))
}
}
pub fn assumed_wf_types_and_report_errors(
&self,
param_env: ty::ParamEnv<'tcx>,
def_id: LocalDefId,
) -> Result<FxIndexSet<Ty<'tcx>>, ErrorGuaranteed> {
self.assumed_wf_types(param_env, def_id)
.map_err(|errors| self.infcx.err_ctxt().report_fulfillment_errors(&errors))
}
pub fn assumed_wf_types(
&self,
param_env: ty::ParamEnv<'tcx>,
def_id: LocalDefId,
) -> Result<FxIndexSet<Ty<'tcx>>, Vec<FulfillmentError<'tcx>>> {
let tcx = self.infcx.tcx;
let mut implied_bounds = FxIndexSet::default();
let mut errors = Vec::new();
for &(ty, span) in tcx.assumed_wf_types(def_id) {
let cause = ObligationCause::misc(span, def_id);
match self
.infcx
.at(&cause, param_env)
.deeply_normalize(ty, &mut **self.engine.borrow_mut())
{
Ok(normalized) => drop(implied_bounds.insert(normalized)),
Err(normalization_errors) => errors.extend(normalization_errors),
};
}
if errors.is_empty() { Ok(implied_bounds) } else { Err(errors) }
}
pub fn make_canonicalized_query_response<T>(
&self,
inference_vars: CanonicalVarValues<'tcx>,
answer: T,
) -> Result<CanonicalQueryResponse<'tcx, T>, NoSolution>
where
T: Debug + TypeFoldable<TyCtxt<'tcx>>,
Canonical<'tcx, QueryResponse<'tcx, T>>: ArenaAllocatable<'tcx>,
{
self.infcx.make_canonicalized_query_response(
inference_vars,
answer,
&mut **self.engine.borrow_mut(),
)
}
}