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various centril nits

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This commit is contained in:
Niko Matsakis 2019-06-24 15:06:58 -04:00
parent d2772e8989
commit b4a3753cfb
1 changed files with 11 additions and 10 deletions
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21
src/librustc/infer/lexical_region_resolve/mod.rs
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@ -218,10 +218,10 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
/// Enforce a constraint like
///
/// ```
/// pick 'r from ['o...]
/// 'r member of ['c...]
/// ```
///
/// We look for all option regions from the list `'o...` that:
/// We look for all choice regions from the list `'c...` that:
///
/// (a) are greater than the current value of `'r` (which is a lower bound)
///
@ -230,8 +230,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
/// (b) are compatible with the upper bounds of `'r` that we can
/// find by traversing the graph.
///
/// From that list, we look for a *minimal* option `'o_min`. If we
/// find one, then we can enforce that `'r: 'o_min`.
/// From that list, we look for a *minimal* option `'c_min`. If we
/// find one, then we can enforce that `'r: 'c_min`.
fn enforce_member_constraint(
&self,
graph: &RegionGraph<'tcx>,
@ -241,7 +241,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
debug!("enforce_member_constraint(member_constraint={:#?})", member_constraint);
// The constraint is some inference variable (`vid`) which
// must be equal to one of the options
// must be equal to one of the options.
let member_vid = match member_constraint.member_region {
ty::ReVar(vid) => *vid,
_ => return false,
@ -254,7 +254,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
VarValue::Value(r) => r,
};
// find all the "upper bounds" -- that is, each region `b` such that
// Find all the "upper bounds" -- that is, each region `b` such that
// `r0 <= b` must hold.
let (member_upper_bounds, _) = self.collect_concrete_regions(
graph,
@ -263,7 +263,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
None,
);
// get an iterator over the *available choice* -- that is,
// Get an iterator over the *available choice* -- that is,
// each choice region `c` where `lb <= c` and `c <= ub` for all the
// upper bounds `ub`.
debug!("enforce_member_constraint: upper_bounds={:#?}", member_upper_bounds);
@ -274,9 +274,9 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
.all(|upper_bound| self.sub_concrete_regions(option, upper_bound.region))
});
// if there >1 option, we only make a choice if there is a
// single *least* choice -- i.e., some available region that
// is `<=` all the others.
// If there is more than one option, we only make a choice if
// there is a single *least* choice -- i.e., some available
// region that is `<=` all the others.
let mut least_choice: ty::Region<'tcx> = match options.next() {
Some(&r) => r,
None => return false,
@ -554,6 +554,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
}
}
// Check that all member constraints are satisfied.
for member_constraint in &self.data.member_constraints {
let member_region = var_data.normalize(self.tcx(), member_constraint.member_region);
let choice_regions = member_constraint