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factor out free_region_binding_scope helper

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This commit is contained in:
Niko Matsakis 2017-11-07 13:18:14 -05:00
parent 8cea0539d1
commit c7c2603e2c
2 changed files with 30 additions and 7 deletions
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8
src/librustc/infer/error_reporting/mod.rs
View File

@ -177,13 +177,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
ty::ReEarlyBound(_) |
ty::ReFree(_) => {
let scope = match *region {
ty::ReEarlyBound(ref br) => {
self.parent_def_id(br.def_id).unwrap()
}
ty::ReFree(ref fr) => fr.scope,
_ => bug!()
};
let scope = region.free_region_binding_scope(self);
let prefix = match *region {
ty::ReEarlyBound(ref br) => {
format!("the lifetime {} as defined on", br.name)

29
src/librustc/ty/sty.rs
View File

@ -1050,6 +1050,35 @@ impl RegionKind {
flags
}
/// Given an early-bound or free region, returns the def-id where it was bound.
/// For example, consider the regions in this snippet of code:
///
/// ```
/// impl<'a> Foo {
/// ^^ -- early bound, declared on an impl
///
/// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
/// ^^ ^^ ^ anonymous, late-bound
/// | early-bound, appears in where-clauses
/// late-bound, appears only in fn args
/// {..}
/// }
/// ```
///
/// Here, `free_region_binding_scope('a)` would return the def-id
/// of the impl, and for all the other highlighted regions, it
/// would return the def-id of the function. In other cases (not shown), this
/// function might return the def-id of a closure.
pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
match self {
ty::ReEarlyBound(br) => {
tcx.parent_def_id(br.def_id).unwrap()
}
ty::ReFree(fr) => fr.scope,
_ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
}
}
}
/// Type utilities