bjoernager/rust
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Auto merge of #111754 - lcnr:recursion-depth, r=matthewjasper

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fix recursion depth handling after confirmation

fixes #111729

I think having to use `Obligation::with_depth` correctly everywhere is very hard because e.g. the nested obligations from `eq` currently do not have the correct obligation depth.

The new solver [completely removes `recursion_depth` from obligations](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/traits/solve/struct.Goal.html) and instead tracks the depth in the solver itself which is far easier to get right. Moving the old solver towards this shouldn't be that hard but is probably somewhat annoying.

r? `@matthewjasper`
This commit is contained in:
bors 2023-05-22 17:56:26 +00:00
commit cfcde247cd
5 changed files with 101 additions and 4 deletions
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23
compiler/rustc_middle/src/traits/mod.rs
View file

@ -701,9 +701,9 @@ impl<'tcx, N> ImplSource<'tcx, N> {
}
pub fn borrow_nested_obligations(&self) -> &[N] {
match &self {
ImplSource::UserDefined(i) => &i.nested[..],
ImplSource::Param(n, _) => &n,
match self {
ImplSource::UserDefined(i) => &i.nested,
ImplSource::Param(n, _) => n,
ImplSource::Builtin(i) => &i.nested,
ImplSource::AutoImpl(d) => &d.nested,
ImplSource::Closure(c) => &c.nested,
@ -717,6 +717,23 @@ impl<'tcx, N> ImplSource<'tcx, N> {
}
}
pub fn borrow_nested_obligations_mut(&mut self) -> &mut [N] {
match self {
ImplSource::UserDefined(i) => &mut i.nested,
ImplSource::Param(n, _) => n,
ImplSource::Builtin(i) => &mut i.nested,
ImplSource::AutoImpl(d) => &mut d.nested,
ImplSource::Closure(c) => &mut c.nested,
ImplSource::Generator(c) => &mut c.nested,
ImplSource::Future(c) => &mut c.nested,
ImplSource::Object(d) => &mut d.nested,
ImplSource::FnPointer(d) => &mut d.nested,
ImplSource::TraitAlias(d) => &mut d.nested,
ImplSource::TraitUpcasting(d) => &mut d.nested,
ImplSource::ConstDestruct(i) => &mut i.nested,
}
}
pub fn map<M, F>(self, f: F) -> ImplSource<'tcx, M>
where
F: FnMut(N) -> M,

6
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -132,6 +132,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
};
// The obligations returned by confirmation are recursively evaluated
// so we need to make sure they have the correct depth.
for subobligation in impl_src.borrow_nested_obligations_mut() {
subobligation.set_depth_from_parent(obligation.recursion_depth);
}
if !obligation.predicate.is_const_if_const() {
// normalize nested predicates according to parent predicate's constness.
impl_src = impl_src.map(|mut o| {