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Allow escaping bound vars during normalize_erasing_regions in new solver

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This commit is contained in:
Michael Goulet
2023-07-13 18:24:37 +00:00
parent bacf5bcbc7
commit 4bcca3294a
4 changed files with 51 additions and 22 deletions
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41
compiler/rustc_trait_selection/src/traits/query/normalize.rs
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@@ -61,8 +61,27 @@ impl<'cx, 'tcx> QueryNormalizeExt<'tcx> for At<'cx, 'tcx> {
self.cause,
);
// 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.
let universes = if value.has_escaping_bound_vars() {
let mut max_visitor =
MaxEscapingBoundVarVisitor { outer_index: ty::INNERMOST, escaping: 0 };
value.visit_with(&mut max_visitor);
vec![None; max_visitor.escaping]
} else {
vec![]
};
if self.infcx.next_trait_solver() {
match crate::solve::deeply_normalize(self, value) {
match crate::solve::deeply_normalize_with_skipped_universes(self, value, universes) {
Ok(value) => return Ok(Normalized { value, obligations: vec![] }),
Err(_errors) => {
return Err(NoSolution);
@@ -81,27 +100,9 @@ impl<'cx, 'tcx> QueryNormalizeExt<'tcx> for At<'cx, 'tcx> {
obligations: vec![],
cache: SsoHashMap::new(),
anon_depth: 0,
universes: vec![],
universes,
};
// 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 };
value.visit_with(&mut max_visitor);
if max_visitor.escaping > 0 {
normalizer.universes.extend((0..max_visitor.escaping).map(|_| None));
}
}
let result = value.try_fold_with(&mut normalizer);
info!(
"normalize::<{}>: result={:?} with {} obligations",