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use crate::mir;
use crate::traits::query::NoSolution;
use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder};
use crate::ty::subst::{Subst, SubstsRef};
use crate::ty::{self, EarlyBinder, Ty, TyCtxt};
#[derive(Debug, Copy, Clone, HashStable, TyEncodable, TyDecodable)]
pub enum NormalizationError<'tcx> {
Type(Ty<'tcx>),
Const(ty::Const<'tcx>),
ConstantKind(mir::ConstantKind<'tcx>),
}
impl<'tcx> NormalizationError<'tcx> {
pub fn get_type_for_failure(&self) -> String {
match self {
NormalizationError::Type(t) => format!("{}", t),
NormalizationError::Const(c) => format!("{}", c),
NormalizationError::ConstantKind(ck) => format!("{}", ck),
}
}
}
impl<'tcx> TyCtxt<'tcx> {
#[tracing::instrument(level = "debug", skip(self, param_env))]
pub fn normalize_erasing_regions<T>(self, param_env: ty::ParamEnv<'tcx>, value: T) -> T
where
T: TypeFoldable<'tcx>,
{
debug!(
"normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
std::any::type_name::<T>(),
value,
param_env,
);
let value = self.erase_regions(value);
debug!(?value);
if !value.has_projections() {
value
} else {
value.fold_with(&mut NormalizeAfterErasingRegionsFolder { tcx: self, param_env })
}
}
pub fn try_normalize_erasing_regions<T>(
self,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> Result<T, NormalizationError<'tcx>>
where
T: TypeFoldable<'tcx>,
{
debug!(
"try_normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
std::any::type_name::<T>(),
value,
param_env,
);
let value = self.erase_regions(value);
debug!(?value);
if !value.has_projections() {
Ok(value)
} else {
let mut folder = TryNormalizeAfterErasingRegionsFolder::new(self, param_env);
value.try_fold_with(&mut folder)
}
}
#[tracing::instrument(level = "debug", skip(self, param_env))]
pub fn normalize_erasing_late_bound_regions<T>(
self,
param_env: ty::ParamEnv<'tcx>,
value: ty::Binder<'tcx, T>,
) -> T
where
T: TypeFoldable<'tcx>,
{
let value = self.erase_late_bound_regions(value);
self.normalize_erasing_regions(param_env, value)
}
pub fn try_normalize_erasing_late_bound_regions<T>(
self,
param_env: ty::ParamEnv<'tcx>,
value: ty::Binder<'tcx, T>,
) -> Result<T, NormalizationError<'tcx>>
where
T: TypeFoldable<'tcx>,
{
let value = self.erase_late_bound_regions(value);
self.try_normalize_erasing_regions(param_env, value)
}
pub fn subst_and_normalize_erasing_regions<T>(
self,
param_substs: SubstsRef<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> T
where
T: TypeFoldable<'tcx>,
{
debug!(
"subst_and_normalize_erasing_regions(\
param_substs={:?}, \
value={:?}, \
param_env={:?})",
param_substs, value, param_env,
);
let substituted = EarlyBinder(value).subst(self, param_substs);
self.normalize_erasing_regions(param_env, substituted)
}
pub fn try_subst_and_normalize_erasing_regions<T>(
self,
param_substs: SubstsRef<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: T,
) -> Result<T, NormalizationError<'tcx>>
where
T: TypeFoldable<'tcx>,
{
debug!(
"subst_and_normalize_erasing_regions(\
param_substs={:?}, \
value={:?}, \
param_env={:?})",
param_substs, value, param_env,
);
let substituted = EarlyBinder(value).subst(self, param_substs);
self.try_normalize_erasing_regions(param_env, substituted)
}
}
struct NormalizeAfterErasingRegionsFolder<'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
}
impl<'tcx> NormalizeAfterErasingRegionsFolder<'tcx> {
fn normalize_generic_arg_after_erasing_regions(
&self,
arg: ty::GenericArg<'tcx>,
) -> ty::GenericArg<'tcx> {
let arg = self.param_env.and(arg);
self.tcx.try_normalize_generic_arg_after_erasing_regions(arg).unwrap_or_else(|_| bug!(
"Failed to normalize {:?}, maybe try to call `try_normalize_erasing_regions` instead",
arg.value
))
}
}
impl<'tcx> TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
self.normalize_generic_arg_after_erasing_regions(ty.into()).expect_ty()
}
fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
self.normalize_generic_arg_after_erasing_regions(c.into()).expect_const()
}
#[inline]
fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
let arg = self.param_env.and(c);
self.tcx
.try_normalize_mir_const_after_erasing_regions(arg)
.unwrap_or_else(|_| bug!("failed to normalize {:?}", c))
}
}
struct TryNormalizeAfterErasingRegionsFolder<'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
}
impl<'tcx> TryNormalizeAfterErasingRegionsFolder<'tcx> {
fn new(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
TryNormalizeAfterErasingRegionsFolder { tcx, param_env }
}
#[instrument(skip(self), level = "debug")]
fn try_normalize_generic_arg_after_erasing_regions(
&self,
arg: ty::GenericArg<'tcx>,
) -> Result<ty::GenericArg<'tcx>, NoSolution> {
let arg = self.param_env.and(arg);
debug!(?arg);
self.tcx.try_normalize_generic_arg_after_erasing_regions(arg)
}
}
impl<'tcx> FallibleTypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'tcx> {
type Error = NormalizationError<'tcx>;
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> {
match self.try_normalize_generic_arg_after_erasing_regions(ty.into()) {
Ok(t) => Ok(t.expect_ty()),
Err(_) => Err(NormalizationError::Type(ty)),
}
}
fn try_fold_const(&mut self, c: ty::Const<'tcx>) -> Result<ty::Const<'tcx>, Self::Error> {
match self.try_normalize_generic_arg_after_erasing_regions(c.into()) {
Ok(t) => Ok(t.expect_const()),
Err(_) => Err(NormalizationError::Const(c)),
}
}
fn try_fold_mir_const(
&mut self,
c: mir::ConstantKind<'tcx>,
) -> Result<mir::ConstantKind<'tcx>, Self::Error> {
let arg = self.param_env.and(c);
match self.tcx.try_normalize_mir_const_after_erasing_regions(arg) {
Ok(c) => Ok(c),
Err(_) => Err(NormalizationError::ConstantKind(c)),
}
}
}