diff options
| -rw-r--r-- | src/librustc/middle/ty.rs | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs index ee56d919fef..6839e8bcc45 100644 --- a/src/librustc/middle/ty.rs +++ b/src/librustc/middle/ty.rs @@ -1368,12 +1368,13 @@ impl<'tcx> PolyTraitRef<'tcx> { } } -/// Binder serves as a synthetic binder for lifetimes. It is used when -/// we wish to replace the escaping higher-ranked lifetimes in a type -/// or something else that is not itself a binder (this is because the -/// `replace_late_bound_regions` function replaces all lifetimes bound -/// by the binder supplied to it; but a type is not a binder, so you -/// must introduce an artificial one). +/// Binder is a binder for higher-ranked lifetimes. It is part of the +/// compiler's representation for things like `for<'a> Fn(&'a int)` +/// (which would be represented by the type `PolyTraitRef == +/// Binder<TraitRef>`). Note that when we skolemize, instantiate, +/// erase, or otherwise "discharge" these bound reons, we change the +/// type from `Binder<T>` to just `T` (see +/// e.g. `liberate_late_bound_regions`). #[deriving(Clone, PartialEq, Eq, Hash, Show)] pub struct Binder<T>(pub T); |