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ty.rs: document/cleanup required_region_bounds a bit

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This commit is contained in:
Niko Matsakis 2015-08-12 15:03:19 -04:00
parent fda9b83960
commit ad700abea4
1 changed files with 8 additions and 7 deletions
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15
src/librustc/middle/ty.rs
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@ -6233,13 +6233,18 @@ impl<'tcx> ctxt<'tcx> {
/// themselves. This should really be a unique type; `FreshTy(0)` is a
/// popular choice.
///
/// NB: in some cases, particularly around higher-ranked bounds,
/// this function returns a kind of conservative approximation.
/// That is, all regions returned by this function are definitely
/// required, but there may be other region bounds that are not
/// returned, as well as requirements like `for<'a> T: 'a`.
///
/// Requires that trait definitions have been processed so that we can
/// elaborate predicates and walk supertraits.
pub fn required_region_bounds(&self,
erased_self_ty: Ty<'tcx>,
predicates: Vec<ty::Predicate<'tcx>>)
-> Vec<ty::Region>
{
-> Vec<ty::Region> {
debug!("required_region_bounds(erased_self_ty={:?}, predicates={:?})",
erased_self_ty,
predicates);
@ -6268,11 +6273,7 @@ impl<'tcx> ctxt<'tcx> {
// construct such an object, but this seems
// correct even if that code changes).
if t == erased_self_ty && !r.has_escaping_regions() {
if r.has_escaping_regions() {
Some(ty::ReStatic)
} else {
Some(r)
}
Some(r)
} else {
None
}