bjoernager/rust
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This commit is contained in:
jackh726 2021-08-24 22:26:48 -04:00
parent 9891e470b1
commit af14db14f4
3 changed files with 68 additions and 41 deletions
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51
compiler/rustc_trait_selection/src/traits/query/normalize.rs
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@ -67,6 +67,16 @@ impl<'cx, 'tcx> AtExt<'tcx> for At<'cx, 'tcx> {
universes: vec![],
};
// This is actually a consequence by the way `normalize_erasing_regions` works currently.
// Because it needs to call the `normalize_generic_arg_after_erasing_regions`, it folds
// through tys and consts in a `TypeFoldable`. Importantly, it skips binders, leaving us
// with trying to normalize with escaping bound vars.
//
// Here, we just add the universes that we *would* have created had we passed through the binders.
//
// We *could* replace escaping bound vars eagerly here, but it doesn't seem really necessary.
// The rest of the code is already set up to be lazy about replacing bound vars,
// and only when we actually have to normalize.
if value.has_escaping_bound_vars() {
let mut max_visitor =
MaxEscapingBoundVarVisitor { outer_index: ty::INNERMOST, escaping: 0 };
@ -183,12 +193,8 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
return ty;
}
// N.b. while we want to call `super_fold_with(self)` on `ty` before
// normalization, we wait until we know whether we need to normalize the
// current type. If we do, then we only fold the ty *after* replacing bound
// vars with placeholders. This means that nested types don't need to replace
// bound vars at the current binder level or above. A key assumption here is
// that folding the type can't introduce new bound vars.
// See note in `rustc_trait_selection::traits::project` about why we
// wait to fold the substs.
// Wrap this in a closure so we don't accidentally return from the outer function
let res = (|| match *ty.kind() {
@ -253,7 +259,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
// We don't expect ambiguity.
if result.is_ambiguous() {
self.error = true;
return ty;
return ty.super_fold_with(self);
}
match self.infcx.instantiate_query_response_and_region_obligations(
@ -271,14 +277,14 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
Err(_) => {
self.error = true;
ty
ty.super_fold_with(self)
}
}
}
Err(NoSolution) => {
self.error = true;
ty
ty.super_fold_with(self)
}
}
}
@ -304,12 +310,12 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
.canonicalize_query_keep_static(self.param_env.and(data), &mut orig_values);
debug!("QueryNormalizer: c_data = {:#?}", c_data);
debug!("QueryNormalizer: orig_values = {:#?}", orig_values);
let normalized_ty = match tcx.normalize_projection_ty(c_data) {
match tcx.normalize_projection_ty(c_data) {
Ok(result) => {
// We don't expect ambiguity.
if result.is_ambiguous() {
self.error = true;
return ty;
return ty.super_fold_with(self);
}
match self.infcx.instantiate_query_response_and_region_obligations(
self.cause,
@ -321,27 +327,26 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
debug!("QueryNormalizer: result = {:#?}", result);
debug!("QueryNormalizer: obligations = {:#?}", obligations);
self.obligations.extend(obligations);
result.normalized_ty
crate::traits::project::PlaceholderReplacer::replace_placeholders(
infcx,
mapped_regions,
mapped_types,
mapped_consts,
&self.universes,
result.normalized_ty,
)
}
Err(_) => {
self.error = true;
ty
ty.super_fold_with(self)
}
}
}
Err(NoSolution) => {
self.error = true;
ty
ty.super_fold_with(self)
}
};
crate::traits::project::PlaceholderReplacer::replace_placeholders(
infcx,
mapped_regions,
mapped_types,
mapped_consts,
&self.universes,
normalized_ty,
)
}
}
_ => ty.super_fold_with(self),