use rustc_infer::infer::relate::{
self, structurally_relate_tys, Relate, RelateResult, TypeRelation,
};
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::{self, InferConst, Ty, TyCtxt};
use tracing::instrument;
pub struct MatchAgainstFreshVars<'tcx> {
tcx: TyCtxt<'tcx>,
}
impl<'tcx> MatchAgainstFreshVars<'tcx> {
pub fn new(tcx: TyCtxt<'tcx>) -> MatchAgainstFreshVars<'tcx> {
MatchAgainstFreshVars { tcx }
}
}
impl<'tcx> TypeRelation<TyCtxt<'tcx>> for MatchAgainstFreshVars<'tcx> {
fn cx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn relate_with_variance<T: Relate<TyCtxt<'tcx>>>(
&mut self,
_: ty::Variance,
_: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
self.relate(a, b)
}
#[instrument(skip(self), level = "trace")]
fn regions(
&mut self,
a: ty::Region<'tcx>,
_b: ty::Region<'tcx>,
) -> RelateResult<'tcx, ty::Region<'tcx>> {
Ok(a)
}
#[instrument(skip(self), level = "trace")]
fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
if a == b {
return Ok(a);
}
match (a.kind(), b.kind()) {
(
_,
&ty::Infer(ty::FreshTy(_))
| &ty::Infer(ty::FreshIntTy(_))
| &ty::Infer(ty::FreshFloatTy(_)),
) => Ok(a),
(&ty::Infer(_), _) | (_, &ty::Infer(_)) => {
Err(TypeError::Sorts(ExpectedFound::new(true, a, b)))
}
(&ty::Error(guar), _) | (_, &ty::Error(guar)) => Ok(Ty::new_error(self.cx(), guar)),
_ => structurally_relate_tys(self, a, b),
}
}
#[instrument(skip(self), level = "trace")]
fn consts(
&mut self,
a: ty::Const<'tcx>,
b: ty::Const<'tcx>,
) -> RelateResult<'tcx, ty::Const<'tcx>> {
if a == b {
return Ok(a);
}
match (a.kind(), b.kind()) {
(_, ty::ConstKind::Infer(InferConst::Fresh(_))) => {
return Ok(a);
}
(ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
return Err(TypeError::ConstMismatch(ExpectedFound::new(true, a, b)));
}
_ => {}
}
relate::structurally_relate_consts(self, a, b)
}
fn binders<T>(
&mut self,
a: ty::Binder<'tcx, T>,
b: ty::Binder<'tcx, T>,
) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
where
T: Relate<TyCtxt<'tcx>>,
{
Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
}
}