1 //! Methods for normalizing when you don't care about regions (and
2 //! aren't doing type inference). If either of those things don't
3 //! apply to you, use `infcx.normalize(...)`.
5 //! The methods in this file use a `TypeFolder` to recursively process
6 //! contents, invoking the underlying
7 //! `normalize_generic_arg_after_erasing_regions` query for each type
8 //! or constant found within. (This underlying query is what is cached.)
11 use crate::traits::query::NoSolution;
12 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder};
13 use crate::ty::subst::{Subst, SubstsRef};
14 use crate::ty::{self, Ty, TyCtxt};
16 #[derive(Debug, Copy, Clone, HashStable, TyEncodable, TyDecodable)]
17 pub enum NormalizationError<'tcx> {
19 Const(ty::Const<'tcx>),
20 ConstantKind(mir::ConstantKind<'tcx>),
23 impl<'tcx> NormalizationError<'tcx> {
24 pub fn get_type_for_failure(&self) -> String {
26 NormalizationError::Type(t) => format!("{}", t),
27 NormalizationError::Const(c) => format!("{}", c),
28 NormalizationError::ConstantKind(ck) => format!("{}", ck),
33 impl<'tcx> TyCtxt<'tcx> {
34 /// Erase the regions in `value` and then fully normalize all the
35 /// types found within. The result will also have regions erased.
37 /// This should only be used outside of type inference. For example,
38 /// it assumes that normalization will succeed.
39 pub fn normalize_erasing_regions<T>(self, param_env: ty::ParamEnv<'tcx>, value: T) -> T
41 T: TypeFoldable<'tcx>,
44 "normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
45 std::any::type_name::<T>(),
50 // Erase first before we do the real query -- this keeps the
51 // cache from being too polluted.
52 let value = self.erase_regions(value);
55 if !value.has_projections() {
58 value.fold_with(&mut NormalizeAfterErasingRegionsFolder { tcx: self, param_env })
62 /// Tries to erase the regions in `value` and then fully normalize all the
63 /// types found within. The result will also have regions erased.
65 /// Contrary to `normalize_erasing_regions` this function does not assume that normalization
67 pub fn try_normalize_erasing_regions<T>(
69 param_env: ty::ParamEnv<'tcx>,
71 ) -> Result<T, NormalizationError<'tcx>>
73 T: TypeFoldable<'tcx>,
76 "try_normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
77 std::any::type_name::<T>(),
82 // Erase first before we do the real query -- this keeps the
83 // cache from being too polluted.
84 let value = self.erase_regions(value);
87 if !value.has_projections() {
90 let mut folder = TryNormalizeAfterErasingRegionsFolder::new(self, param_env);
91 value.try_fold_with(&mut folder)
95 /// If you have a `Binder<'tcx, T>`, you can do this to strip out the
96 /// late-bound regions and then normalize the result, yielding up
97 /// a `T` (with regions erased). This is appropriate when the
98 /// binder is being instantiated at the call site.
100 /// N.B., currently, higher-ranked type bounds inhibit
101 /// normalization. Therefore, each time we erase them in
102 /// codegen, we need to normalize the contents.
103 pub fn normalize_erasing_late_bound_regions<T>(
105 param_env: ty::ParamEnv<'tcx>,
106 value: ty::Binder<'tcx, T>,
109 T: TypeFoldable<'tcx>,
111 let value = self.erase_late_bound_regions(value);
112 self.normalize_erasing_regions(param_env, value)
115 /// Monomorphizes a type from the AST by first applying the
116 /// in-scope substitutions and then normalizing any associated
118 /// Panics if normalization fails. In case normalization might fail
119 /// use `try_subst_and_normalize_erasing_regions` instead.
120 pub fn subst_and_normalize_erasing_regions<T>(
122 param_substs: SubstsRef<'tcx>,
123 param_env: ty::ParamEnv<'tcx>,
127 T: TypeFoldable<'tcx>,
130 "subst_and_normalize_erasing_regions(\
134 param_substs, value, param_env,
136 let substituted = value.subst(self, param_substs);
137 self.normalize_erasing_regions(param_env, substituted)
140 /// Monomorphizes a type from the AST by first applying the
141 /// in-scope substitutions and then trying to normalize any associated
142 /// types. Contrary to `subst_and_normalize_erasing_regions` this does
143 /// not assume that normalization succeeds.
144 pub fn try_subst_and_normalize_erasing_regions<T>(
146 param_substs: SubstsRef<'tcx>,
147 param_env: ty::ParamEnv<'tcx>,
149 ) -> Result<T, NormalizationError<'tcx>>
151 T: TypeFoldable<'tcx>,
154 "subst_and_normalize_erasing_regions(\
158 param_substs, value, param_env,
160 let substituted = value.subst(self, param_substs);
161 self.try_normalize_erasing_regions(param_env, substituted)
165 struct NormalizeAfterErasingRegionsFolder<'tcx> {
167 param_env: ty::ParamEnv<'tcx>,
170 impl<'tcx> NormalizeAfterErasingRegionsFolder<'tcx> {
171 #[instrument(skip(self), level = "debug")]
172 fn normalize_generic_arg_after_erasing_regions(
174 arg: ty::GenericArg<'tcx>,
175 ) -> ty::GenericArg<'tcx> {
176 let arg = self.param_env.and(arg);
179 self.tcx.try_normalize_generic_arg_after_erasing_regions(arg).unwrap_or_else(|_| bug!(
180 "Failed to normalize {:?}, maybe try to call `try_normalize_erasing_regions` instead",
186 impl<'tcx> TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
187 fn tcx(&self) -> TyCtxt<'tcx> {
191 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
192 self.normalize_generic_arg_after_erasing_regions(ty.into()).expect_ty()
195 fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
196 self.normalize_generic_arg_after_erasing_regions(c.into()).expect_const()
200 fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
201 // FIXME: This *probably* needs canonicalization too!
202 let arg = self.param_env.and(c);
204 .try_normalize_mir_const_after_erasing_regions(arg)
205 .unwrap_or_else(|_| bug!("failed to normalize {:?}", c))
209 struct TryNormalizeAfterErasingRegionsFolder<'tcx> {
211 param_env: ty::ParamEnv<'tcx>,
214 impl<'tcx> TryNormalizeAfterErasingRegionsFolder<'tcx> {
215 fn new(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
216 TryNormalizeAfterErasingRegionsFolder { tcx, param_env }
219 #[instrument(skip(self), level = "debug")]
220 fn try_normalize_generic_arg_after_erasing_regions(
222 arg: ty::GenericArg<'tcx>,
223 ) -> Result<ty::GenericArg<'tcx>, NoSolution> {
224 let arg = self.param_env.and(arg);
227 self.tcx.try_normalize_generic_arg_after_erasing_regions(arg)
231 impl<'tcx> TypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'tcx> {
232 type Error = NormalizationError<'tcx>;
234 fn tcx(&self) -> TyCtxt<'tcx> {
239 impl<'tcx> FallibleTypeFolder<'tcx> for TryNormalizeAfterErasingRegionsFolder<'tcx> {
240 fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> {
241 match self.try_normalize_generic_arg_after_erasing_regions(ty.into()) {
242 Ok(t) => Ok(t.expect_ty()),
243 Err(_) => Err(NormalizationError::Type(ty)),
247 fn try_fold_const(&mut self, c: ty::Const<'tcx>) -> Result<ty::Const<'tcx>, Self::Error> {
248 match self.try_normalize_generic_arg_after_erasing_regions(c.into()) {
249 Ok(t) => Ok(t.expect_const()),
250 Err(_) => Err(NormalizationError::Const(c)),
254 fn try_fold_mir_const(
256 c: mir::ConstantKind<'tcx>,
257 ) -> Result<mir::ConstantKind<'tcx>, Self::Error> {
258 // FIXME: This *probably* needs canonicalization too!
259 let arg = self.param_env.and(c);
260 match self.tcx.try_normalize_mir_const_after_erasing_regions(arg) {
262 Err(_) => Err(NormalizationError::ConstantKind(c)),