use crate::infer::InferCtxt;
use crate::traits::{ObligationCause, ObligationCtxt};
use rustc_data_structures::fx::FxIndexSet;
use rustc_infer::infer::resolve::OpportunisticRegionResolver;
use rustc_infer::infer::InferOk;
use rustc_middle::infer::canonical::{OriginalQueryValues, QueryRegionConstraints};
use rustc_middle::ty::{self, ParamEnv, Ty, TypeFolder, TypeVisitableExt};
use rustc_span::def_id::LocalDefId;
pub use rustc_middle::traits::query::OutlivesBound;
pub type Bounds<'a, 'tcx: 'a> = impl Iterator<Item = OutlivesBound<'tcx>> + 'a;
pub trait InferCtxtExt<'a, 'tcx> {
fn implied_outlives_bounds(
&self,
param_env: ty::ParamEnv<'tcx>,
body_id: LocalDefId,
ty: Ty<'tcx>,
) -> Vec<OutlivesBound<'tcx>>;
fn implied_bounds_tys(
&'a self,
param_env: ty::ParamEnv<'tcx>,
body_id: LocalDefId,
tys: FxIndexSet<Ty<'tcx>>,
) -> Bounds<'a, 'tcx>;
}
impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> {
#[instrument(level = "debug", skip(self, param_env, body_id), ret)]
fn implied_outlives_bounds(
&self,
param_env: ty::ParamEnv<'tcx>,
body_id: LocalDefId,
ty: Ty<'tcx>,
) -> Vec<OutlivesBound<'tcx>> {
let ty = self.resolve_vars_if_possible(ty);
let ty = OpportunisticRegionResolver::new(self).fold_ty(ty);
assert!(!ty.has_non_region_infer());
let mut canonical_var_values = OriginalQueryValues::default();
let canonical_ty =
self.canonicalize_query_keep_static(param_env.and(ty), &mut canonical_var_values);
let Ok(canonical_result) = self.tcx.implied_outlives_bounds(canonical_ty) else {
return vec![];
};
let mut constraints = QueryRegionConstraints::default();
let Ok(InferOk { value, obligations }) = self
.instantiate_nll_query_response_and_region_obligations(
&ObligationCause::dummy(),
param_env,
&canonical_var_values,
canonical_result,
&mut constraints,
)
else {
return vec![];
};
assert_eq!(&obligations, &[]);
if !constraints.is_empty() {
let span = self.tcx.def_span(body_id);
debug!(?constraints);
if !constraints.member_constraints.is_empty() {
span_bug!(span, "{:#?}", constraints.member_constraints);
}
let ocx = ObligationCtxt::new(self);
let cause = ObligationCause::misc(span, body_id);
for &constraint in &constraints.outlives {
ocx.register_obligation(self.query_outlives_constraint_to_obligation(
constraint,
cause.clone(),
param_env,
));
}
let errors = ocx.select_all_or_error();
if !errors.is_empty() {
self.tcx.sess.delay_span_bug(
span,
"implied_outlives_bounds failed to solve obligations from instantiation",
);
}
};
value
}
fn implied_bounds_tys(
&'a self,
param_env: ParamEnv<'tcx>,
body_id: LocalDefId,
tys: FxIndexSet<Ty<'tcx>>,
) -> Bounds<'a, 'tcx> {
tys.into_iter().flat_map(move |ty| self.implied_outlives_bounds(param_env, body_id, ty))
}
}