rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Rollup merge of #143895 - compiler-errors:trait-wc-item-bound-host-eff, r=oli-obk

Browse Source 
Dont collect assoc ty item bounds from trait where clause for host effect predicates

For background, we uplift `where Self::Assoc: Trait` bounds in a trait's where clauses into *item bounds* on `type Assoc;`. This is because before we *had* syntactical item bounds, users would express their item bounds like so.

Let's opt out of doing this same behavior for `HostEffect` predicates like `where Self::Assoc: [const] Trait`. I left a comment in the code:

```rust
// FIXME(const_trait_impl): We *could* uplift the
// `where Self::Assoc: [const] Trait` bounds from the parent trait
// here too, but we'd need to split `const_conditions` into two
// queries (like we do for `trait_explicit_predicates_and_bounds`)
// since we need to also filter the predicates *out* of the const
// conditions or they lead to cycles in the trait solver when
// utilizing these bounds. For now, let's do nothing.
```

As an aside, this was an ICE that was only triggerable when building libraries and not binaries because we never were calling `tcx.ensure_ok().explicit_implied_const_bounds(def_id);` on associated types like we should have been. I adjusted the calls to `ensure_ok` to make sure this happens, so we catch bugs like this in the future more easily.

As another aside, I fixed the bound uplifting logic for *always const* predicates, since those act like normal clauses and have no notion of conditional constness.

r? ```@oli-obk``` ```@fee1-dead``` or anyone really

Fixes rust-lang/rust#133275
This commit is contained in:
León Orell Valerian Liehr
2025-07-17 03:58:34 +02:00
committed by GitHub
parent 36a362bff5 8daf98b623
commit 7ea74358c8
6 changed files with 73 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
compiler/rustc_hir_analysis/src/check/check.rs
View File

@@ -889,8 +889,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
tcx.ensure_ok().predicates_of(def_id);
tcx.ensure_ok().explicit_item_bounds(def_id);
tcx.ensure_ok().explicit_item_self_bounds(def_id);
tcx.ensure_ok().item_bounds(def_id);
tcx.ensure_ok().item_self_bounds(def_id);
if tcx.is_conditionally_const(def_id) {
tcx.ensure_ok().explicit_implied_const_bounds(def_id);
tcx.ensure_ok().const_conditions(def_id);
@@ -1044,8 +1042,12 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
let has_type = match assoc_item.container {
ty::AssocItemContainer::Impl => true,
ty::AssocItemContainer::Trait => {
tcx.ensure_ok().item_bounds(def_id);
tcx.ensure_ok().item_self_bounds(def_id);
tcx.ensure_ok().explicit_item_bounds(def_id);
tcx.ensure_ok().explicit_item_self_bounds(def_id);
if tcx.is_conditionally_const(def_id) {
tcx.ensure_ok().explicit_implied_const_bounds(def_id);
tcx.ensure_ok().const_conditions(def_id);
}
res = res.and(check_trait_item(tcx, def_id));
assoc_item.defaultness(tcx).has_value()
}