diff options
| -rw-r--r-- | compiler/rustc_typeck/src/variance/constraints.rs | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/compiler/rustc_typeck/src/variance/constraints.rs b/compiler/rustc_typeck/src/variance/constraints.rs index 1c8ac10818c..33c27ce86dd 100644 --- a/compiler/rustc_typeck/src/variance/constraints.rs +++ b/compiler/rustc_typeck/src/variance/constraints.rs @@ -223,8 +223,8 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> { self.add_constraints_from_region(current, lt, variance_i) } GenericArgKind::Type(ty) => self.add_constraints_from_ty(current, ty, variance_i), - GenericArgKind::Const(_) => { - // Consts impose no constraints. + GenericArgKind::Const(val) => { + self.add_constraints_from_const(current, val, variance_i) } } } @@ -263,7 +263,8 @@ 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_const(current, len, variance); self.add_constraints_from_ty(current, typ, variance); } @@ -385,13 +386,32 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> { self.add_constraints_from_region(current, lt, variance_i) } GenericArgKind::Type(ty) => self.add_constraints_from_ty(current, ty, variance_i), - GenericArgKind::Const(_) => { - // Consts impose no constraints. + GenericArgKind::Const(val) => { + self.add_constraints_from_const(current, val, variance) } } } } + /// Adds constraints appropriate for a const expression `val` + /// in a context with ambient variance `variance` + fn add_constraints_from_const( + &mut self, + current: &CurrentItem, + val: &ty::Const<'tcx>, + variance: VarianceTermPtr<'a>, + ) { + debug!("add_constraints_from_const(val={:?}, variance={:?})", val, variance); + + match &val.val { + ty::ConstKind::Unevaluated(uv) => { + let substs = uv.substs(self.tcx()); + self.add_constraints_from_invariant_substs(current, substs, variance); + } + _ => {} + } + } + /// Adds constraints appropriate for a function with signature /// `sig` appearing in a context with ambient variance `variance` fn add_constraints_from_sig( |