1
Fork 0

Make assoc types work with ?const opt=out

This commit is contained in:
Deadbeef 2021-07-26 17:25:01 +08:00
parent 8c2a1e8e43
commit 1fa712d0ba
No known key found for this signature in database
GPG key ID: 027DF9338862ADDD
7 changed files with 24 additions and 27 deletions

View file

@ -3261,8 +3261,13 @@ impl<'hir> Node<'hir> {
} }
} }
/// Returns `Constness::Const` when this node is a const fn/impl/item. /// Returns `Constness::Const` when this node is a const fn/impl/item,
pub fn constness(&self) -> Constness { ///
/// HACK(fee1-dead): or an associated type in a trait. This works because
/// only typeck cares about const trait predicates, so although the predicates
/// query would return const predicates when it does not need to be const,
/// it wouldn't have any effect.
pub fn constness_for_typeck(&self) -> Constness {
match self { match self {
Node::Item(Item { Node::Item(Item {
kind: ItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..), kind: ItemKind::Fn(FnSig { header: FnHeader { constness, .. }, .. }, ..),
@ -3280,6 +3285,7 @@ impl<'hir> Node<'hir> {
Node::Item(Item { kind: ItemKind::Const(..), .. }) Node::Item(Item { kind: ItemKind::Const(..), .. })
| Node::TraitItem(TraitItem { kind: TraitItemKind::Const(..), .. }) | Node::TraitItem(TraitItem { kind: TraitItemKind::Const(..), .. })
| Node::TraitItem(TraitItem { kind: TraitItemKind::Type(..), .. })
| Node::ImplItem(ImplItem { kind: ImplItemKind::Const(..), .. }) => Constness::Const, | Node::ImplItem(ImplItem { kind: ImplItemKind::Const(..), .. }) => Constness::Const,
_ => Constness::NotConst, _ => Constness::NotConst,

View file

@ -1292,28 +1292,12 @@ pub fn check_type_bounds<'tcx>(
}; };
tcx.infer_ctxt().enter(move |infcx| { tcx.infer_ctxt().enter(move |infcx| {
// if the item is inside a const impl, we transform the predicates to be const.
let constness = impl_ty let constness = impl_ty
.container .container
.impl_def_id() .impl_def_id()
.map(|did| tcx.impl_constness(did)) .map(|did| tcx.impl_constness(did))
.unwrap_or(hir::Constness::NotConst); .unwrap_or(hir::Constness::NotConst);
let pred_map = match constness {
hir::Constness::NotConst => |p, _| p,
hir::Constness::Const => |p: ty::Predicate<'tcx>, tcx: TyCtxt<'tcx>| {
p.kind()
.map_bound(|kind| match kind {
ty::PredicateKind::Trait(mut tp) => {
tp.constness = hir::Constness::Const;
ty::PredicateKind::Trait(tp)
}
kind => kind,
})
.to_predicate(tcx)
},
};
let inh = Inherited::with_constness(infcx, impl_ty.def_id.expect_local(), constness); let inh = Inherited::with_constness(infcx, impl_ty.def_id.expect_local(), constness);
let infcx = &inh.infcx; let infcx = &inh.infcx;
let mut selcx = traits::SelectionContext::new(&infcx); let mut selcx = traits::SelectionContext::new(&infcx);
@ -1332,7 +1316,7 @@ pub fn check_type_bounds<'tcx>(
.explicit_item_bounds(trait_ty.def_id) .explicit_item_bounds(trait_ty.def_id)
.iter() .iter()
.map(|&(bound, span)| { .map(|&(bound, span)| {
let concrete_ty_bound = pred_map(bound.subst(tcx, rebased_substs), tcx); let concrete_ty_bound = bound.subst(tcx, rebased_substs);
debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound);
traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound) traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound)
@ -1350,10 +1334,7 @@ pub fn check_type_bounds<'tcx>(
debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate); debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate);
obligation.predicate = normalized_predicate; obligation.predicate = normalized_predicate;
inh.register_predicates(obligations.into_iter().map(|mut o| { inh.register_predicates(obligations);
o.predicate = pred_map(o.predicate, tcx);
o
}));
inh.register_predicate(obligation); inh.register_predicate(obligation);
} }

View file

@ -174,7 +174,7 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
} }
fn default_constness_for_trait_bounds(&self) -> hir::Constness { fn default_constness_for_trait_bounds(&self) -> hir::Constness {
self.tcx.hir().get(self.body_id).constness() self.tcx.hir().get(self.body_id).constness_for_typeck()
} }
fn get_type_parameter_bounds( fn get_type_parameter_bounds(

View file

@ -98,7 +98,7 @@ impl Inherited<'a, 'tcx> {
pub(super) fn new(infcx: InferCtxt<'a, 'tcx>, def_id: LocalDefId) -> Self { pub(super) fn new(infcx: InferCtxt<'a, 'tcx>, def_id: LocalDefId) -> Self {
let tcx = infcx.tcx; let tcx = infcx.tcx;
let item_id = tcx.hir().local_def_id_to_hir_id(def_id); let item_id = tcx.hir().local_def_id_to_hir_id(def_id);
Self::with_constness(infcx, def_id, tcx.hir().get(item_id).constness()) Self::with_constness(infcx, def_id, tcx.hir().get(item_id).constness_for_typeck())
} }
pub(super) fn with_constness( pub(super) fn with_constness(

View file

@ -364,7 +364,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
} }
fn default_constness_for_trait_bounds(&self) -> hir::Constness { fn default_constness_for_trait_bounds(&self) -> hir::Constness {
self.node().constness() self.node().constness_for_typeck()
} }
fn get_type_parameter_bounds( fn get_type_parameter_bounds(

View file

@ -1,5 +1,7 @@
// FIXME(fee1-dead): this should have a better error message // FIXME(fee1-dead): this should have a better error message
#![feature(const_trait_impl)] #![feature(const_trait_impl)]
#![feature(const_trait_bound_opt_out)]
#![allow(incomplete_features)]
struct NonConstAdd(i32); struct NonConstAdd(i32);
@ -20,4 +22,12 @@ impl const Foo for NonConstAdd {
//~^ ERROR //~^ ERROR
} }
trait Baz {
type Qux: ?const std::ops::Add;
}
impl const Baz for NonConstAdd {
type Qux = NonConstAdd; // OK
}
fn main() {} fn main() {}

View file

@ -1,5 +1,5 @@
error[E0277]: cannot add `NonConstAdd` to `NonConstAdd` error[E0277]: cannot add `NonConstAdd` to `NonConstAdd`
--> $DIR/assoc-type.rs:19:5 --> $DIR/assoc-type.rs:21:5
| |
LL | type Bar: std::ops::Add; LL | type Bar: std::ops::Add;
| ------------- required by this bound in `Foo::Bar` | ------------- required by this bound in `Foo::Bar`