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introduce constrain_regions helper

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This commit is contained in:
Niko Matsakis 2019-05-28 17:02:07 -04:00
parent aab48c963a
commit 2eb3fcc10d
1 changed files with 25 additions and 20 deletions
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45
src/librustc/infer/opaque_types/mod.rs
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@ -1,6 +1,3 @@
use rustc_data_structures::fx::FxHashMap;
use syntax_pos::Span;
use crate::hir;
use crate::hir::def_id::DefId;
use crate::hir::Node;
@ -11,6 +8,7 @@
use crate::ty::subst::{InternalSubsts, Kind, SubstsRef, UnpackedKind};
use crate::ty::{self, GenericParamDefKind, Ty, TyCtxt};
use crate::util::nodemap::DefIdMap;
use rustc_data_structures::fx::FxHashMap;
pub type OpaqueTypeMap<'tcx> = DefIdMap<OpaqueTypeDecl<'tcx>>;
@ -303,11 +301,10 @@ pub fn constrain_opaque_type<FRR: FreeRegionRelations<'tcx>>(
let required_region_bounds = tcx.required_region_bounds(opaque_type, bounds.predicates);
debug_assert!(!required_region_bounds.is_empty());
for region in required_region_bounds {
concrete_ty.visit_with(&mut OpaqueTypeOutlivesVisitor {
infcx: self,
least_region: region,
span,
for required_region in required_region_bounds {
concrete_ty.visit_with(&mut ConstrainOpaqueTypeRegionVisitor {
tcx: self.tcx,
op: |r| self.sub_regions(infer::CallReturn(span), required_region, r),
});
}
return;
@ -389,7 +386,10 @@ pub fn constrain_opaque_type<FRR: FreeRegionRelations<'tcx>>(
let least_region = least_region.unwrap_or(tcx.lifetimes.re_static);
debug!("constrain_opaque_types: least_region={:?}", least_region);
concrete_ty.visit_with(&mut OpaqueTypeOutlivesVisitor { infcx: self, least_region, span });
concrete_ty.visit_with(&mut ConstrainOpaqueTypeRegionVisitor {
tcx: self.tcx,
op: |r| self.sub_regions(infer::CallReturn(span), least_region, r),
});
}
/// Given the fully resolved, instantiated type for an opaque
@ -471,13 +471,18 @@ pub fn infer_opaque_definition_from_instantiation(
//
// We ignore any type parameters because impl trait values are assumed to
// capture all the in-scope type parameters.
struct OpaqueTypeOutlivesVisitor<'a, 'tcx> {
infcx: &'a InferCtxt<'a, 'tcx>,
least_region: ty::Region<'tcx>,
span: Span,
struct ConstrainOpaqueTypeRegionVisitor<'tcx, OP>
where
OP: FnMut(ty::Region<'tcx>),
{
tcx: TyCtxt<'tcx>,
op: OP,
}
impl<'tcx> TypeVisitor<'tcx> for OpaqueTypeOutlivesVisitor<'_, 'tcx> {
impl<'tcx, OP> TypeVisitor<'tcx> for ConstrainOpaqueTypeRegionVisitor<'tcx, OP>
where
OP: FnMut(ty::Region<'tcx>),
{
fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &ty::Binder<T>) -> bool {
t.skip_binder().visit_with(self);
false // keep visiting
@ -488,7 +493,7 @@ fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
// ignore bound regions, keep visiting
ty::ReLateBound(_, _) => false,
_ => {
self.infcx.sub_regions(infer::CallReturn(self.span), self.least_region, r);
(self.op)(r);
false
}
}
@ -504,23 +509,23 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
ty::Closure(def_id, ref substs) => {
// Skip lifetime parameters of the enclosing item(s)
for upvar_ty in substs.upvar_tys(def_id, self.infcx.tcx) {
for upvar_ty in substs.upvar_tys(def_id, self.tcx) {
upvar_ty.visit_with(self);
}
substs.closure_sig_ty(def_id, self.infcx.tcx).visit_with(self);
substs.closure_sig_ty(def_id, self.tcx).visit_with(self);
}
ty::Generator(def_id, ref substs, _) => {
// Skip lifetime parameters of the enclosing item(s)
// Also skip the witness type, because that has no free regions.
for upvar_ty in substs.upvar_tys(def_id, self.infcx.tcx) {
for upvar_ty in substs.upvar_tys(def_id, self.tcx) {
upvar_ty.visit_with(self);
}
substs.return_ty(def_id, self.infcx.tcx).visit_with(self);
substs.yield_ty(def_id, self.infcx.tcx).visit_with(self);
substs.return_ty(def_id, self.tcx).visit_with(self);
substs.yield_ty(def_id, self.tcx).visit_with(self);
}
_ => {
ty.super_visit_with(self);