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Some cleanups in our normalization logic #109171

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Merged
bors merged 2 commits into from
Mar 16, 2023
Merged

Some cleanups in our normalization logic #109171

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d3d537b
Exhaustively match over all alias kinds
oli-obk Mar 7, 2023
d87fbb9
Deduplicate logic between projection normalization with and without e…
oli-obk Mar 8, 2023
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Deduplicate logic between projection normalization with and without e… 
…scaping bound vars
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@oli-obk
oli-obk committed Mar 15, 2023
commit d87fbb918c5a9d3dc7f8d1d801fd17a622484a85
80 changes: 21 additions & 59 deletions compiler/rustc_trait_selection/src/traits/query/normalize.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -257,62 +257,20 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>

ty::Opaque => ty.try_super_fold_with(self)?,

ty::Projection if !data.has_escaping_bound_vars() => {
// This branch is just an optimization: when we don't have escaping bound vars,
// we don't need to replace them with placeholders (see branch below).

let tcx = self.infcx.tcx;
let data = data.try_fold_with(self)?;

let mut orig_values = OriginalQueryValues::default();
// HACK(matthewjasper) `'static` is special-cased in selection,
// so we cannot canonicalize it.
let c_data = self
.infcx
.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 result = tcx.normalize_projection_ty(c_data)?;
// We don't expect ambiguity.
if result.is_ambiguous() {
// Rustdoc normalizes possibly not well-formed types, so only
// treat this as a bug if we're not in rustdoc.
if !tcx.sess.opts.actually_rustdoc {
tcx.sess.delay_span_bug(
DUMMY_SP,
format!("unexpected ambiguity: {:?} {:?}", c_data, result),
);
}
return Err(NoSolution);
}
let InferOk { value: result, obligations } =
self.infcx.instantiate_query_response_and_region_obligations(
self.cause,
self.param_env,
&orig_values,
result,
)?;
debug!("QueryNormalizer: result = {:#?}", result);
debug!("QueryNormalizer: obligations = {:#?}", obligations);
self.obligations.extend(obligations);

let res = result.normalized_ty;
// `tcx.normalize_projection_ty` may normalize to a type that still has
// unevaluated consts, so keep normalizing here if that's the case.
if res != ty && res.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
res.try_super_fold_with(self)?
} else {
res
}
}

ty::Projection => {
// See note in `rustc_trait_selection::traits::project`

let tcx = self.infcx.tcx;
let infcx = self.infcx;
let (data, mapped_regions, mapped_types, mapped_consts) =
BoundVarReplacer::replace_bound_vars(infcx, &mut self.universes, data);
// Just an optimization: When we don't have escaping bound vars,
// we don't need to replace them with placeholders.
let (data, maps) = if data.has_escaping_bound_vars() {
let (data, mapped_regions, mapped_types, mapped_consts) =
BoundVarReplacer::replace_bound_vars(infcx, &mut self.universes, data);
(data, Some((mapped_regions, mapped_types, mapped_consts)))
} else {
(data, None)
};
let data = data.try_fold_with(self)?;

let mut orig_values = OriginalQueryValues::default();
Expand Down Expand Up @@ -346,14 +304,18 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
debug!("QueryNormalizer: result = {:#?}", result);
debug!("QueryNormalizer: obligations = {:#?}", obligations);
self.obligations.extend(obligations);
let res = PlaceholderReplacer::replace_placeholders(
infcx,
mapped_regions,
mapped_types,
mapped_consts,
&self.universes,
result.normalized_ty,
);
let res = if let Some((mapped_regions, mapped_types, mapped_consts)) = maps {
PlaceholderReplacer::replace_placeholders(
infcx,
mapped_regions,
mapped_types,
mapped_consts,
&self.universes,
result.normalized_ty,
)
} else {
result.normalized_ty
};
// `tcx.normalize_projection_ty` may normalize to a type that still has
// unevaluated consts, so keep normalizing here if that's the case.
if res != ty && res.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
Expand Down