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Add type constraints from const parameters

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Co-Authored-By: Gabriel Smith <yodaldevoid@users.noreply.github.com>
This commit is contained in:
varkor 2019-02-20 01:13:19 +00:00
parent 7f2a4f7822
commit f7f60eef50
1 changed files with 42 additions and 7 deletions
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49
src/librustc_typeck/variance/constraints.rs
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@ -4,7 +4,8 @@
//! We walk the set of items and, for each member, generate new constraints.
use hir::def_id::DefId;
use rustc::ty::subst::{UnpackedKind, SubstsRef};
use rustc::mir::interpret::ConstValue;
use rustc::ty::subst::{SubstsRef, UnpackedKind};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::hir;
use rustc::hir::itemlikevisit::ItemLikeVisitor;
@ -229,12 +230,19 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
// Trait are always invariant so we can take advantage of that.
let variance_i = self.invariant(variance);
for ty in substs.types() {
self.add_constraints_from_ty(current, ty, variance_i);
}
for region in substs.regions() {
self.add_constraints_from_region(current, region, variance_i);
for k in substs {
match k.unpack() {
UnpackedKind::Lifetime(lt) => {
self.add_constraints_from_region(current, lt, variance_i)
}
UnpackedKind::Type(ty) => {
self.add_constraints_from_ty(current, ty, variance_i)
}
UnpackedKind::Const(ct) => {
self.add_constraints_from_const(current, ct, variance_i)
}
}
}
}
@ -267,7 +275,11 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
self.add_constraints_from_mt(current, &ty::TypeAndMut { ty, mutbl }, variance);
}
ty::Array(typ, _) |
ty::Array(typ, len) => {
self.add_constraints_from_ty(current, typ, variance);
self.add_constraints_from_const(current, len, variance);
}
ty::Slice(typ) => {
self.add_constraints_from_ty(current, typ, variance);
}
@ -383,6 +395,9 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
UnpackedKind::Type(ty) => {
self.add_constraints_from_ty(current, ty, variance_i)
}
UnpackedKind::Const(ct) => {
self.add_constraints_from_const(current, ct, variance_i)
}
}
}
}
@ -434,6 +449,26 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
}
}
fn add_constraints_from_const(
&mut self,
current: &CurrentItem,
ct: &ty::LazyConst<'tcx>,
variance: VarianceTermPtr<'a>
) {
debug!(
"add_constraints_from_const(ct={:?}, variance={:?})",
ct,
variance
);
if let ty::LazyConst::Evaluated(ct) = ct {
self.add_constraints_from_ty(current, ct.ty, variance);
if let ConstValue::Param(ref data) = ct.val {
self.add_constraint(current, data.index, variance);
}
}
}
/// Adds constraints appropriate for a mutability-type pair
/// appearing in a context with ambient variance `variance`
fn add_constraints_from_mt(&mut self,