Dont collect assoc ty item bounds from trait where clause for host effect predicates #143895

compiler-errors · 2025-07-13T16:30:33Z

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:

// 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 #133275

rustbot · 2025-07-13T16:30:38Z

This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

…fect predicates

compiler-errors · 2025-07-13T16:31:02Z

compiler/rustc_hir_analysis/src/check/check.rs

@@ -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);


We don't need to ensure these queries, since they're just computed from the explicit ones we're ensuring above.

compiler-errors · 2025-07-13T16:32:42Z

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1042,8 +1040,12 @@ 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);


Ensuring the explicit flavor of the item bounds queries, and also making sure to ensure the const ones too.

oli-obk · 2025-07-14T08:17:05Z

compiler/rustc_hir_analysis/src/collect/item_bounds.rs

@@ -124,6 +124,7 @@ fn remap_gat_vars_and_recurse_into_nested_projections<'tcx>(
        ty::ClauseKind::Trait(tr) => tr.self_ty(),
        ty::ClauseKind::Projection(proj) => proj.projection_term.self_ty(),
        ty::ClauseKind::TypeOutlives(outlives) => outlives.0,
+        ty::ClauseKind::HostEffect(host) => host.self_ty(),
        _ => return None,


seems like a good candidate for an exhaustive match

oli-obk · 2025-07-14T08:18:16Z

@bors r+

bors · 2025-07-14T08:18:18Z

📌 Commit 8daf98b has been approved by oli-obk

It is now in the queue for this repository.

…d-host-eff, r=oli-obk 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#133275

Rollup of 15 pull requests Successful merges: - #142304 (tests: Add `RUST_BACKTRACE` and `-Cpanic` revisions to `panic-main.rs` test) - #143388 (Various refactors to the LTO handling code) - #143409 (Enable xgot feature for mips64 musl targets) - #143592 (UWP: link ntdll functions using raw-dylib) - #143595 (add `const_make_global`; err for `const_allocate` ptrs if didn't call) - #143678 (Added error for invalid char cast) - #143820 (Fixed a core crate compilation failure when enabling the `optimize_for_size` feature on some targets) - #143829 (Trim `BorrowedCursor` API) - #143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - #143851 (ci cleanup: rustdoc-gui-test now installs browser-ui-test) - #143856 (Linting public reexport of private dependencies) - #143895 (Dont collect assoc ty item bounds from trait where clause for host effect predicates) - #143922 (Improve path segment joining) - #143964 (Fix handling of SCRIPT_ARG in docker images) - #144016 (trait_sel: `MetaSized` always holds temporarily) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 15 pull requests Successful merges: - #142304 (tests: Add `RUST_BACKTRACE` and `-Cpanic` revisions to `panic-main.rs` test) - #143388 (Various refactors to the LTO handling code) - #143409 (Enable xgot feature for mips64 musl targets) - #143592 (UWP: link ntdll functions using raw-dylib) - #143595 (add `const_make_global`; err for `const_allocate` ptrs if didn't call) - #143678 (Added error for invalid char cast) - #143820 (Fixed a core crate compilation failure when enabling the `optimize_for_size` feature on some targets) - #143829 (Trim `BorrowedCursor` API) - #143851 (ci cleanup: rustdoc-gui-test now installs browser-ui-test) - #143856 (Linting public reexport of private dependencies) - #143895 (Dont collect assoc ty item bounds from trait where clause for host effect predicates) - #143922 (Improve path segment joining) - #143964 (Fix handling of SCRIPT_ARG in docker images) - #144002 (Update poison.rs) - #144016 (trait_sel: `MetaSized` always holds temporarily) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #143895 - compiler-errors:trait-wc-item-bound-host-eff, r=oli-obk 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 #133275

rustbot assigned oli-obk Jul 13, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 13, 2025

compiler-errors added 3 commits July 13, 2025 16:31

Ensure proper item queries for assoc tys

ef726a4

Dont collect assoc ty item bounds from trait where clause for host ef…

549a5d8

…fect predicates

Imply always-const host effects the same as any other item bound

8daf98b

compiler-errors force-pushed the trait-wc-item-bound-host-eff branch from 6eebb24 to 8daf98b Compare July 13, 2025 16:32

compiler-errors commented Jul 13, 2025

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oli-obk reviewed Jul 14, 2025

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oli-obk approved these changes Jul 14, 2025

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 14, 2025

fmease mentioned this pull request Jul 16, 2025

Rollup of 15 pull requests #144041

Closed

fmease mentioned this pull request Jul 17, 2025

Rollup of 15 pull requests #144044

Merged

bors merged commit 7ea7435 into rust-lang:master Jul 17, 2025
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rustbot added this to the 1.90.0 milestone Jul 17, 2025

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Dont collect assoc ty item bounds from trait where clause for host effect predicates #143895

Dont collect assoc ty item bounds from trait where clause for host effect predicates #143895

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Dont collect assoc ty item bounds from trait where clause for host effect predicates #143895

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