Remove the `At` struct in favor of just splatting the fields into function parameters. by fallible-algebra · Pull Request #163448 · rust-lang/rust

fallible-algebra · 2026-09-28T14:43:42Z

View all comments

AKA "splat the At"

Draft as I still need to rebase.

rustbot · 2026-09-28T15:14:51Z

changes to the core type system

cc @lcnr

Some changes occurred in engine.rs, potentially modifying the public API of ObligationCtxt.

cc @lcnr

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

clippy is developed in its own repository. If possible, consider making this change to rust-lang/rust-clippy instead.

cc @rust-lang/clippy

rustbot · 2026-09-28T15:14:54Z

r? @JonathanBrouwer

rustbot has assigned @JonathanBrouwer.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

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Owners of files modified in this PR: compiler, types
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rustbot · 2026-09-28T15:14:56Z

⚠️ Warning ⚠️

The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.
- 8a8c7f9
You can start a rebase with the following commands:
```
$ # rebase
$ git pull --rebase https://github.com/rust-lang/rust.git main
$ git push --force-with-lease
```

jackh726 · 2026-09-28T19:50:02Z

A lot of the *_at feel pretty bad. (e.g. eq_at...) Is there not a reason that we can't just have eq always take a ObligationCause and ParamEnv?

lcnr · 2026-09-29T09:18:31Z

            if infcx
-                .at(&cause, param_env)
-                .relate(DefineOpaqueTypes::Yes, source_ty, ty::Variance::Invariant, target_ty)
+                .relate_at(


jup, please just infcx.relate. no need for the at 😁

View changes since the review

lcnr · 2026-09-29T09:20:10Z

            let impl_ty = self.normalize(span, tcx.type_of(impl_def_id).instantiate(tcx, args));
            let self_ty = self.normalize(span, Unnormalized::new_wip(self_ty));
-            match self.at(&self.misc(span), self.param_env).eq(
+            match self.eq_at(


i'd like us to be consistent with the order of fields

I think normalize does span, relevant data and looking at ObligatioNCtxt, it's Span, env, data. So please change all methods to also have that order 😊

View changes since the review

lcnr · 2026-09-29T09:26:53Z

-                    expression_ty
-                })
+            fcx.eq_at(
+                // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs


comment should stay on DefineOpaqueTypes::Yes

also. Why are we using at here. We should be using some FnCtxt::eq method 🤔 we have FnCtxt::demand_eq but no eq which doesn't eagerly error. I guess that makes sense as eq outside of a probe always taints the root context. I guess that's separate from this PR 😁 so nothing to do here

View changes since the review

still relevant

lcnr · 2026-09-29T09:27:56Z

-            infcx: self.infcx,
-            cause: self.cause,
-            param_env: self.param_env,
+            infcx: &self,


why &self 🤔 shouldn't self already be &InferCtxt?

View changes since the review

all uses of &self here

JonathanBrouwer · 2026-10-05T17:26:52Z

(feel free to reroll a reviewer when this is ready)

fallible-algebra · 2026-10-06T09:12:13Z

@lcnr the tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs test is failing, which i assume is the result of one of my rebase decisions failing. Going to be combing through to find where this is happening, but it's a bit frustrating 😅

ShoyuVanilla · 2026-10-06T09:15:50Z

That test was actually written by me 😅 How does it fail? It's a test with compilation failure after all 🤔

rust-log-analyzer · 2026-10-06T09:39:15Z

The job test-aarch64-gnu-llvm-22-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [ui] tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs#next stdout ----

error in revision `next`: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "next" "--check-cfg" "cfg(test,FALSE,next,old)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/impl-trait/failed-to-resolve-instance-ice-105488.next" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "--edition=2015" "-Znext-solver"
stdout: none
--- stderr -------------------------------
note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: unexpected rigid alias in layout_of after normalization: Alias(Yes, Alias { kind: Projection { def_id: DefId(0:4 ~ failed_to_resolve_instance_ice_105488[cce2]::MyFnOnce::Output) }, args: [Alias(Yes, Alias { kind: Opaque { def_id: DefId(0:21 ~ failed_to_resolve_instance_ice_105488[cce2]::my_fn_1::{opaque#0}) }, args: [], .. })], .. })
   |
   = note: delayed at compiler/rustc_ty_utils/src/layout.rs:856:61
              0: <std::backtrace::Backtrace>::create
              1: <rustc_errors::DiagCtxtInner>::emit_diagnostic
              2: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
              3: <rustc_errors::diagnostic::Diag>::emit_err
              4: <rustc_errors::DiagCtxtHandle>::delayed_bug::<alloc::string::String>
              5: rustc_ty_utils::layout::layout_of
              6: rustc_query_impl::query_vtables::layout_of::invoke_provider_fn::__rust_begin_short_backtrace
              7: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 16]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 16]>>
              8: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>, false>
              9: rustc_query_impl::query_vtables::layout_of::execute_query_non_incr::__rust_end_short_backtrace
             10: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
             11: rustc_mir_transform::pass_manager::run_passes_inner
             12: rustc_mir_transform::run_analysis_to_runtime_passes
             13: rustc_mir_transform::mir_drops_elaborated_and_const_checked
             14: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::invoke_provider_fn::__rust_begin_short_backtrace
             15: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_data_structures::vec_cache::VecCache<rustc_hir_id::OwnerId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 8]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 8]>>
             16: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
             17: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::execute_query_non_incr::__rust_end_short_backtrace
             18: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
             19: rustc_data_structures::sync::parallel::par_for_each_in::<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}>
             20: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
             21: rustc_interface::passes::analysis
             22: rustc_query_impl::query_vtables::analysis::invoke_provider_fn::__rust_begin_short_backtrace
             23: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 0]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 0]>>
             24: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
             25: rustc_query_impl::query_vtables::analysis::execute_query_non_incr::__rust_end_short_backtrace
             26: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>
             27: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}>
             28: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>
             29: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
             30: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
             31: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             32: <std::sys::thread::unix::Thread>::new::thread_start
---
note: please make sure that you have updated to the latest nightly

note: rustc 1.101.0-nightly (3aac2cef6 2026-10-06) running on aarch64-unknown-linux-gnu

note: compiler flags: -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -Z next-solver=coherence -C rpath -C debuginfo=0 -Z next-solver

query stack during panic:
end of query stack
------------------------------------------

---- [ui] tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs#next stdout end ----
---- [ui] tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs stdout ----
Saved the actual stderr to `/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained/overflowing-opaque-incorrectly-unconstrained.stderr`
diff of stderr:

11 LL | type X = impl std::ops::Add<Output = X>;
12    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
13 
- error[E0275]: overflow evaluating the requirement `X == _`
+ error: aborting due to 1 previous error
15 
---
To only update this specific test, also pass `--test-args traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "--edition=2015" "-Znext-solver"
stdout: none
--- stderr -------------------------------
error: item does not constrain `X::{opaque#0}`
##[error]  --> /checkout/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs:16:12
   |
LL |     pub fn new() -> X {
   |            ^^^
   |
   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
note: this opaque type is supposed to be constrained
  --> /checkout/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs:10:10
   |
LL | type X = impl std::ops::Add<Output = X>;
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error
------------------------------------------

---- [ui] tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs stdout end ----
---- [ui] tests/ui/type-alias-impl-trait/mututally-recursive-overflow.rs#next stdout ----

error in revision `next`: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/type-alias-impl-trait/mututally-recursive-overflow.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--cfg" "next" "--check-cfg" "cfg(test,FALSE,next,old)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/type-alias-impl-trait/mututally-recursive-overflow.next" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "--edition=2021" "-Znext-solver"
stdout: none
--- stderr -------------------------------
note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: unexpected rigid alias in layout_of after normalization: Alias(Yes, Alias { kind: Opaque { def_id: DefId(0:18 ~ mututally_recursive_overflow[3dbb]::{impl#1}::Assoc::{opaque#0}) }, args: [()], .. })
   |
   = note: delayed at compiler/rustc_ty_utils/src/layout.rs:856:61
              0: <std::backtrace::Backtrace>::create
              1: <rustc_errors::DiagCtxtInner>::emit_diagnostic
              2: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
              3: <rustc_errors::diagnostic::Diag>::emit_err
              4: <rustc_errors::DiagCtxtHandle>::delayed_bug::<alloc::string::String>
              5: rustc_ty_utils::layout::layout_of
              6: rustc_query_impl::query_vtables::layout_of::invoke_provider_fn::__rust_begin_short_backtrace
              7: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 16]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 16]>>
              8: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>, false>
              9: rustc_query_impl::query_vtables::layout_of::execute_query_non_incr::__rust_end_short_backtrace
             10: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
             11: rustc_mir_transform::pass_manager::run_passes_inner
             12: rustc_mir_transform::run_analysis_to_runtime_passes
             13: rustc_mir_transform::mir_drops_elaborated_and_const_checked
             14: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::invoke_provider_fn::__rust_begin_short_backtrace
             15: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_data_structures::vec_cache::VecCache<rustc_hir_id::OwnerId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 8]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 8]>>
             16: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
             17: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::execute_query_non_incr::__rust_end_short_backtrace
             18: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
             19: rustc_data_structures::sync::parallel::par_for_each_in::<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}>
             20: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
             21: rustc_interface::passes::analysis
             22: rustc_query_impl::query_vtables::analysis::invoke_provider_fn::__rust_begin_short_backtrace
             23: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_impl::execution::execute_job_non_incr<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 0]>>::{closure#0}, rustc_middle::query::erase::ErasedData<[u8; 0]>>
             24: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
             25: rustc_query_impl::query_vtables::analysis::execute_query_non_incr::__rust_end_short_backtrace
             26: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>
             27: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}>
             28: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>
             29: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
             30: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
             31: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             32: <std::sys::thread::unix::Thread>::new::thread_start
---
note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly

note: rustc 1.101.0-nightly (3aac2cef6 2026-10-06) running on aarch64-unknown-linux-gnu

note: compiler flags: -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -Z next-solver=coherence -C rpath -C debuginfo=0 -Z next-solver

query stack during panic:
end of query stack
------------------------------------------

ShoyuVanilla · 2026-10-06T10:49:19Z

@bors try jobs=test-aarch64-apple-1,test-aarch64-apple-2

Remove the `At` struct in favor of just splatting the fields into function parameters. try-job: test-aarch64-apple-1 try-job: test-aarch64-apple-2

rust-log-analyzer · 2026-10-06T12:10:45Z

The job test-aarch64-apple-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [ui] tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs#next stdout ----

error in revision `next`: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2/bin/rustc" "/Users/runner/work/rust/rust/tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/work/rust/rust/vendor" "--sysroot" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2" "--target=aarch64-apple-darwin" "--cfg" "next" "--check-cfg" "cfg(test,FALSE,next,old)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/ui/impl-trait/failed-to-resolve-instance-ice-105488.next" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/Users/runner/work/rust/rust/build/aarch64-apple-darwin/native/rust-test-helpers" "--edition=2015" "-Znext-solver"
stdout: none
--- stderr -------------------------------
note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: unexpected rigid alias in layout_of after normalization: Alias(Yes, Alias { kind: Projection { def_id: DefId(0:4 ~ failed_to_resolve_instance_ice_105488[cce2]::MyFnOnce::Output) }, args: [Alias(Yes, Alias { kind: Opaque { def_id: DefId(0:21 ~ failed_to_resolve_instance_ice_105488[cce2]::my_fn_1::{opaque#0}) }, args: [], .. })], .. })
   |
   = note: delayed at compiler/rustc_ty_utils/src/layout.rs:856:61
              0: <std::backtrace::Backtrace>::create
              1: <rustc_errors::DiagCtxtInner>::emit_diagnostic
              2: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
              3: <rustc_errors::diagnostic::Diag>::emit_err
              4: <rustc_errors::DiagCtxtHandle>::delayed_bug::<alloc::string::String>
              5: rustc_ty_utils::layout::layout_of
              6: rustc_query_impl::query_vtables::layout_of::invoke_provider_fn::__rust_begin_short_backtrace
              7: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>, false>
              8: rustc_query_impl::query_vtables::layout_of::execute_query_non_incr::__rust_end_short_backtrace
              9: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
             10: rustc_mir_transform::pass_manager::run_passes_inner
             11: rustc_mir_transform::run_analysis_to_runtime_passes
             12: rustc_mir_transform::mir_drops_elaborated_and_const_checked
             13: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::invoke_provider_fn::__rust_begin_short_backtrace
             14: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
             15: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::execute_query_non_incr::__rust_end_short_backtrace
             16: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
             17: rustc_data_structures::sync::parallel::par_for_each_in::<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}>
             18: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
             19: rustc_interface::passes::analysis
             20: rustc_query_impl::query_vtables::analysis::invoke_provider_fn::__rust_begin_short_backtrace
             21: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
             22: rustc_query_impl::query_vtables::analysis::execute_query_non_incr::__rust_end_short_backtrace
             23: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>
             24: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}>
             25: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>
             26: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
             27: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             28: <std::sys::thread::unix::Thread>::new::thread_start
             29: __pthread_cond_wait
---
note: please make sure that you have updated to the latest nightly

note: rustc 1.101.0-nightly (4bbdb576f 2026-10-06) running on aarch64-apple-darwin

note: compiler flags: -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo -Z ignore-directory-in-diagnostics-source-blocks=/Users/runner/work/rust/rust/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -Z next-solver=coherence -C rpath -C debuginfo=0 -Z next-solver

query stack during panic:
end of query stack
------------------------------------------

---- [ui] tests/ui/impl-trait/failed-to-resolve-instance-ice-105488.rs#next stdout end ----
---- [ui] tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs stdout ----
Saved the actual stderr to `/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained/overflowing-opaque-incorrectly-unconstrained.stderr`
diff of stderr:

11 LL | type X = impl std::ops::Add<Output = X>;
12    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
13 
- error[E0275]: overflow evaluating the requirement `X == _`
+ error: aborting due to 1 previous error
15 
---
To only update this specific test, also pass `--test-args traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2/bin/rustc" "/Users/runner/work/rust/rust/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/work/rust/rust/vendor" "--sysroot" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2" "--target=aarch64-apple-darwin" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/Users/runner/work/rust/rust/build/aarch64-apple-darwin/native/rust-test-helpers" "--edition=2015" "-Znext-solver"
stdout: none
--- stderr -------------------------------
error: item does not constrain `X::{opaque#0}`
##[error]  --> /Users/runner/work/rust/rust/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs:16:12
   |
LL |     pub fn new() -> X {
   |            ^^^
   |
   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
note: this opaque type is supposed to be constrained
  --> /Users/runner/work/rust/rust/tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs:10:10
   |
LL | type X = impl std::ops::Add<Output = X>;
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error
------------------------------------------

---- [ui] tests/ui/traits/next-solver/diagnostics/overflowing-opaque-incorrectly-unconstrained.rs stdout end ----
---- [ui] tests/ui/type-alias-impl-trait/mututally-recursive-overflow.rs#next stdout ----

error in revision `next`: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2/bin/rustc" "/Users/runner/work/rust/rust/tests/ui/type-alias-impl-trait/mututally-recursive-overflow.rs" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/Users/runner/work/rust/rust/vendor" "--sysroot" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/stage2" "--target=aarch64-apple-darwin" "--cfg" "next" "--check-cfg" "cfg(test,FALSE,next,old)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/ui/type-alias-impl-trait/mututally-recursive-overflow.next" "-Znext-solver=coherence" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/Users/runner/work/rust/rust/build/aarch64-apple-darwin/native/rust-test-helpers" "--edition=2021" "-Znext-solver"
stdout: none
--- stderr -------------------------------
note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: unexpected rigid alias in layout_of after normalization: Alias(Yes, Alias { kind: Opaque { def_id: DefId(0:18 ~ mututally_recursive_overflow[3dbb]::{impl#1}::Assoc::{opaque#0}) }, args: [()], .. })
   |
   = note: delayed at compiler/rustc_ty_utils/src/layout.rs:856:61
              0: <std::backtrace::Backtrace>::create
              1: <rustc_errors::DiagCtxtInner>::emit_diagnostic
              2: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
              3: <rustc_errors::diagnostic::Diag>::emit_err
              4: <rustc_errors::DiagCtxtHandle>::delayed_bug::<alloc::string::String>
              5: rustc_ty_utils::layout::layout_of
              6: rustc_query_impl::query_vtables::layout_of::invoke_provider_fn::__rust_begin_short_backtrace
              7: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefaultCache<rustc_middle::ty::PseudoCanonicalInput<rustc_middle::ty::Ty>, rustc_middle::query::erase::ErasedData<[u8; 16]>>, false>
              8: rustc_query_impl::query_vtables::layout_of::execute_query_non_incr::__rust_end_short_backtrace
              9: <rustc_mir_transform::known_panics_lint::KnownPanicsLint as rustc_mir_transform::pass_manager::MirLint>::run_lint
             10: rustc_mir_transform::pass_manager::run_passes_inner
             11: rustc_mir_transform::run_analysis_to_runtime_passes
             12: rustc_mir_transform::mir_drops_elaborated_and_const_checked
             13: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::invoke_provider_fn::__rust_begin_short_backtrace
             14: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
             15: rustc_query_impl::query_vtables::mir_drops_elaborated_and_const_checked::execute_query_non_incr::__rust_end_short_backtrace
             16: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
             17: rustc_data_structures::sync::parallel::par_for_each_in::<&rustc_span::def_id::LocalDefId, &[rustc_span::def_id::LocalDefId], <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}>
             18: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
             19: rustc_interface::passes::analysis
             20: rustc_query_impl::query_vtables::analysis::invoke_provider_fn::__rust_begin_short_backtrace
             21: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
             22: rustc_query_impl::query_vtables::analysis::execute_query_non_incr::__rust_end_short_backtrace
             23: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>
             24: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>::{closure#2}>
             25: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::compiler_entrypoint::{closure#0}::{closure#1}>
             26: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
             27: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::compiler_entrypoint::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             28: <std::sys::thread::unix::Thread>::new::thread_start
             29: __pthread_cond_wait
           

note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly

note: rustc 1.101.0-nightly (4bbdb576f 2026-10-06) running on aarch64-apple-darwin

note: compiler flags: -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/Users/runner/.cargo -Z ignore-directory-in-diagnostics-source-blocks=/Users/runner/work/rust/rust/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -Z next-solver=coherence -C rpath -C debuginfo=0 -Z next-solver

query stack during panic:
end of query stack
------------------------------------------

rust-bors · 2026-10-06T13:26:37Z

💔 Test for 4bbdb57 failed: CI. Failed job:

try - test-aarch64-apple-1 (web logs, enhanced plaintext logs)

lcnr

View changes since this review

lcnr · 2026-10-06T13:20:20Z

-                    expression_ty
-                })
+            fcx.eq_at(
+                // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs


still relevant

lcnr · 2026-10-06T13:20:41Z

                                        // and don't allow converting between different structs,
                                        // so there is no way this ever actually defines an opaque
                                        // type. Thus choosing `Yes` is fine.
+                                        &cause,


lcnr · 2026-10-06T13:20:52Z

+            &self.infcx,
+            Unnormalized::new_wip(hidden_type),
+            self.param_env,
+            &cause,


order of arguments

lcnr · 2026-10-06T13:21:00Z

                Unnormalized::new_wip(value),
                universes,
+                self.fcx.param_env,
+                &cause,


lcnr · 2026-10-06T13:22:38Z

-    /// Makes `actual <: expected`. For example, if type-checking a
-    /// call like `foo(x)`, where `foo: fn(i32)`, you might have
-    /// `sup(i32, x)`, since the "expected" type is the type that
-    /// appears in the signature.


don't remove the comment please :>

lcnr · 2026-10-06T13:25:59Z

        value: Unnormalized<'tcx, T>,
        fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
+        param_env: ty::ParamEnv<'tcx>,
+        cause: &ObligationCause<'tcx>,


lcnr · 2026-10-06T13:26:10Z

        ty: Unnormalized<'tcx, Ty<'tcx>>,
        fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
+        param_env: ParamEnv<'tcx>,
+        cause: &ObligationCause<'tcx>,


lcnr · 2026-10-06T13:26:19Z

        ct: Unnormalized<'tcx, ty::Const<'tcx>>,
        fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
+        param_env: ParamEnv<'tcx>,
+        cause: &ObligationCause<'tcx>,


lcnr · 2026-10-06T13:26:29Z

        term: Unnormalized<'tcx, ty::Term<'tcx>>,
        fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
+        param_env: ParamEnv<'tcx>,
+        cause: &ObligationCause<'tcx>,


and order :>

lcnr · 2026-10-06T13:27:09Z

+            )
+            .map(|resolved| infcx.deeply_resolve_ignoring_regions(resolved.value).skip_binder())
+            .unwrap_or(ty.skip_binder());
+        if let Some(new_def_id) = ty.ty_adt_def().map(|adt| adt.did()) {


you pointed to that diff on zulip, why does it exist '^^

Misclick on a rebase I imagine 😅

fallible-algebra · 2026-10-08T09:39:35Z

Closing this in favour of staggering the removal of At (see: #163978).

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fallible-algebra marked this pull request as ready for review September 28, 2026 15:14

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 28, 2026

rustbot assigned JonathanBrouwer Sep 28, 2026

rustbot added the has-merge-commits PR has merge commits, merge with caution. label Sep 28, 2026

fallible-algebra marked this pull request as draft September 28, 2026 15:16

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 28, 2026

lcnr reviewed Sep 29, 2026

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fallible-algebra force-pushed the splat-the-at-4-real branch from 36ab6d4 to 48dcf59 Compare September 30, 2026 12:32

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fallible-algebra force-pushed the splat-the-at-4-real branch from b538be3 to 99a7619 Compare October 5, 2026 14:55

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JonathanBrouwer removed their assignment Oct 5, 2026

fallible-algebra added 10 commits October 6, 2026 10:03

Remove many things lol

ae927d7

bweh

63497de

arghh

caac676

Compiles doesn't it

12f66e1

Actually remove At

9946afa

Reorder method params

ed495bc

Update method names and remove some remaining At calls (attempt 2)

d3275c6

no 'at' suffixes

a5f5b1a

Re-order normalize args

100a637

Fix consequences of rebase

a7fd6b3

fallible-algebra force-pushed the splat-the-at-4-real branch from 99a7619 to a7fd6b3 Compare October 6, 2026 09:03

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lcnr reviewed Oct 6, 2026

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fallible-algebra mentioned this pull request Oct 8, 2026

Copy over some methods from At to InferCtxt #163978

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fallible-algebra closed this Oct 8, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Oct 8, 2026

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fallible-algebra commented Sep 28, 2026 •

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