//! or constant found within. (This underlying query is what is cached.)
use crate::mir;
-use crate::ty::fold::{TypeFoldable, TypeFolder};
+use crate::traits::query::NoSolution;
+use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder};
use crate::ty::subst::{Subst, SubstsRef};
use crate::ty::{self, 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> {
/// Erase the regions in `value` and then fully normalize all the
/// types found within. The result will also have regions erased.
// Erase first before we do the real query -- this keeps the
// cache from being too polluted.
let value = self.erase_regions(value);
+ debug!(?value);
+
if !value.has_projections() {
value
} else {
}
}
+ /// Tries to erase the regions in `value` and then fully normalize all the
+ /// types found within. The result will also have regions erased.
+ ///
+ /// Contrary to `normalize_erasing_regions` this function does not assume that normalization
+ /// succeeds.
+ 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,
+ );
+
+ // Erase first before we do the real query -- this keeps the
+ // cache from being too polluted.
+ 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)
+ }
+ }
+
/// If you have a `Binder<'tcx, T>`, you can do this to strip out the
/// late-bound regions and then normalize the result, yielding up
/// a `T` (with regions erased). This is appropriate when the
/// Monomorphizes a type from the AST by first applying the
/// in-scope substitutions and then normalizing any associated
/// types.
+ /// Panics if normalization fails. In case normalization might fail
+ /// use `try_subst_and_normalize_erasing_regions` instead.
pub fn subst_and_normalize_erasing_regions<T>(
self,
param_substs: SubstsRef<'tcx>,
let substituted = value.subst(self, param_substs);
self.normalize_erasing_regions(param_env, substituted)
}
+
+ /// Monomorphizes a type from the AST by first applying the
+ /// in-scope substitutions and then trying to normalize any associated
+ /// types. Contrary to `subst_and_normalize_erasing_regions` this does
+ /// not assume that normalization succeeds.
+ 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 = value.subst(self, param_substs);
+ self.try_normalize_erasing_regions(param_env, substituted)
+ }
}
struct NormalizeAfterErasingRegionsFolder<'tcx> {
}
impl<'tcx> NormalizeAfterErasingRegionsFolder<'tcx> {
+ #[instrument(skip(self), level = "debug")]
fn normalize_generic_arg_after_erasing_regions(
&self,
arg: ty::GenericArg<'tcx>,
) -> ty::GenericArg<'tcx> {
let arg = self.param_env.and(arg);
- self.tcx.normalize_generic_arg_after_erasing_regions(arg)
+ debug!(?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 TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
+impl<'tcx> TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
// FIXME: This *probably* needs canonicalization too!
let arg = self.param_env.and(c);
- self.tcx.normalize_mir_const_after_erasing_regions(arg)
+ 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> TypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'tcx> {
+ type Error = NormalizationError<'tcx>;
+
+ fn tcx(&self) -> TyCtxt<'tcx> {
+ self.tcx
+ }
+}
+
+impl<'tcx> FallibleTypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'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: &'tcx ty::Const<'tcx>,
+ ) -> Result<&'tcx 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> {
+ // FIXME: This *probably* needs canonicalization too!
+ 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)),
+ }
}
}
projects / rust.git / blobdiff