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small const generics cleanup #88557

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merged 3 commits into from
Sep 3, 2021
Merged

small const generics cleanup #88557

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fc2a265
cleanup const generics FIXME
lcnr Sep 1, 2021
7207194
update FIXME
lcnr Sep 1, 2021
d18ff40
use the correct feature gate
lcnr Sep 1, 2021
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35 changes: 5 additions & 30 deletions compiler/rustc_trait_selection/src/traits/object_safety.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -820,10 +820,10 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
}
}

fn visit_const(&mut self, ct: &ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
// First check if the type of this constant references `Self`.
self.visit_ty(ct.ty)?;

fn visit_unevaluated_const(
&mut self,
uv: ty::Unevaluated<'tcx>,
) -> ControlFlow<Self::BreakTy> {
// Constants can only influence object safety if they reference `Self`.
// This is only possible for unevaluated constants, so we walk these here.
//
Expand All @@ -837,7 +837,7 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
// This shouldn't really matter though as we can't really use any
// constants which are not considered const evaluatable.
use rustc_middle::mir::abstract_const::Node;
if let Ok(Some(ct)) = AbstractConst::from_const(self.tcx, ct) {
if let Ok(Some(ct)) = AbstractConst::new(self.tcx, uv.shrink()) {
const_evaluatable::walk_abstract_const(self.tcx, ct, |node| match node.root() {
Node::Leaf(leaf) => {
let leaf = leaf.subst(self.tcx, ct.substs);
Expand All @@ -852,31 +852,6 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
ControlFlow::CONTINUE
}
}

fn visit_predicate(&mut self, pred: ty::Predicate<'tcx>) -> ControlFlow<Self::BreakTy> {
if let ty::PredicateKind::ConstEvaluatable(ct) = pred.kind().skip_binder() {
// FIXME(generic_const_exprs): We should probably deduplicate the logic for
// `AbstractConst`s here, it might make sense to change `ConstEvaluatable` to
// take a `ty::Const` instead.
use rustc_middle::mir::abstract_const::Node;
if let Ok(Some(ct)) = AbstractConst::new(self.tcx, ct) {
const_evaluatable::walk_abstract_const(self.tcx, ct, |node| match node.root() {
Node::Leaf(leaf) => {
let leaf = leaf.subst(self.tcx, ct.substs);
self.visit_const(leaf)
}
Node::Cast(_, _, ty) => self.visit_ty(ty),
Node::Binop(..) | Node::UnaryOp(..) | Node::FunctionCall(_, _) => {
ControlFlow::CONTINUE
}
})
} else {
ControlFlow::CONTINUE
}
} else {
pred.super_visit_with(self)
}
}
}

value
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2 changes: 1 addition & 1 deletion compiler/rustc_typeck/src/outlives/implicit_infer.rs
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Expand Up @@ -120,7 +120,7 @@ fn insert_required_predicates_to_be_wf<'tcx>(
// Luckily the only types contained in default substs are type
// parameters which don't matter here.
//
// FIXME(const_generics): Once more complex const parameter types
// FIXME(const_param_types): Once complex const parameter types
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// are allowed, this might be incorrect. I think that we will still be
// fine, as all outlives relations of the const param types should also
// be part of the adt containing it, but we should still both update the
Expand Down