Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Remove lub_empty from lexical region resolve #115224

Merged
merged 3 commits into from
Aug 26, 2023
Merged

Remove lub_empty from lexical region resolve #115224

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
78da436
Remove lub_empty from lexical region resolve
spastorino Aug 25, 2023
e2efb6a
Check that universe can name other universe instead of equality
spastorino Aug 25, 2023
b92840a
Merge if and match expressions that don't make sense to have separated
spastorino Aug 26, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
91 changes: 30 additions & 61 deletions compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@ use rustc_data_structures::graph::implementation::{
use rustc_data_structures::intern::Interned;
use rustc_index::{IndexSlice, IndexVec};
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::PlaceholderRegion;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{ReEarlyBound, ReErased, ReError, ReFree, ReStatic};
use rustc_middle::ty::{ReLateBound, RePlaceholder, ReVar};
Expand Down Expand Up @@ -173,38 +172,6 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
}
}

/// Gets the LUb of a given region and the empty region
fn lub_empty(&self, a_region: Region<'tcx>) -> Result<Region<'tcx>, PlaceholderRegion> {
match *a_region {
ReLateBound(..) | ReErased => {
bug!("cannot relate region: {:?}", a_region);
}

ReVar(v_id) => {
span_bug!(
self.var_infos[v_id].origin.span(),
"lub invoked with non-concrete regions: {:?}",
a_region,
);
}

ReStatic => {
// nothing lives longer than `'static`
Ok(self.tcx().lifetimes.re_static)
}

ReError(_) => Ok(a_region),

ReEarlyBound(_) | ReFree(_) => {
// All empty regions are less than early-bound, free,
// and scope regions.
Ok(a_region)
}

RePlaceholder(placeholder) => Err(placeholder),
}
}

fn expansion(&self, var_values: &mut LexicalRegionResolutions<'tcx>) {
// In the first pass, we expand region vids according to constraints we
// have previously found. In the second pass, we loop through the region
Expand Down Expand Up @@ -247,27 +214,25 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
true
}
VarValue::Value(cur_region) => {
let lub = match self.lub_empty(cur_region) {
Ok(r) => r,
// If the empty and placeholder regions are in the same universe,
// then the LUB is the Placeholder region (which is the cur_region).
// If they are not in the same universe, the LUB is the Static lifetime.
Err(placeholder) if a_universe == placeholder.universe => {
cur_region
match *cur_region {
// If this empty region is from a universe that can name the
// placeholder universe, then the LUB is the Placeholder region
// (which is the cur_region). Otherwise, the LUB is the Static
// lifetime.
RePlaceholder(placeholder)
if !a_universe.can_name(placeholder.universe) =>
{
let lub = self.tcx().lifetimes.re_static;
debug!(
"Expanding value of {:?} from {:?} to {:?}",
b_vid, cur_region, lub
);

*b_data = VarValue::Value(lub);
true
}
Err(_) => self.tcx().lifetimes.re_static,
};

if lub == cur_region {
false
} else {
debug!(
"Expanding value of {:?} from {:?} to {:?}",
b_vid, cur_region, lub
);

*b_data = VarValue::Value(lub);
true

_ => false,
}
}

Expand Down Expand Up @@ -341,15 +306,19 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {

match *b_data {
VarValue::Empty(empty_ui) => {
let lub = match self.lub_empty(a_region) {
Ok(r) => r,
// If this empty region is from a universe that can
// name the placeholder, then the placeholder is
// larger; otherwise, the only ancestor is `'static`.
Err(placeholder) if empty_ui.can_name(placeholder.universe) => {
ty::Region::new_placeholder(self.tcx(), placeholder)
let lub = match *a_region {
RePlaceholder(placeholder) => {
// If this empty region is from a universe that can
// name the placeholder, then the placeholder is
// larger; otherwise, the only ancestor is `'static`.
if empty_ui.can_name(placeholder.universe) {
ty::Region::new_placeholder(self.tcx(), placeholder)
} else {
self.tcx().lifetimes.re_static
}
}
Err(_) => self.tcx().lifetimes.re_static,

_ => a_region,
};

debug!("Expanding value of {:?} from empty lifetime to {:?}", b_vid, lub);
Expand Down