Unify `TraitRefs` and `PolyTraitRefs` in `ValuePairs`
I did this recently with `FnSigs` and `PolyFnSigs` but didn't think to do it with `TraitRefs` and `PolyTraitRefs`.
Currently we always do this:
```
use rustc_fluent_macro::fluent_messages;
...
fluent_messages! { "./example.ftl" }
```
But there is no need, we can just do this everywhere:
```
rustc_fluent_macro::fluent_messages! { "./example.ftl" }
```
which is shorter.
The `fluent_messages!` macro produces uses of
`crate::{D,Subd}iagnosticMessage`, which means that every crate using
the macro must have this import:
```
use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
```
This commit changes the macro to instead use
`rustc_errors::{D,Subd}iagnosticMessage`, which avoids the need for the
imports.
Remove `HirId` from `QPath::LangItem`
Remove `HirId` from `QPath::LangItem`, since there was only *one* use-case (`ObligationCauseCode::AwaitableExpr`), which we can instead recover by walking the HIR tree.
Move EagerResolution to rustc_infer::infer::resolve
`EagerResolver` fits better in `rustc_infer::infer::resolver`.
Started to disentagle #118118 that has a lot of unrelated things.
r? `@compiler-errors` `@lcnr`
Cache flags for `ty::Const`
Not sure if this has been attempted yet, but worth a shot. It does make the code simpler in `rustc_type_ir`, since we can assume that consts have a `flags` method that is no-cost.
r? `@ghost`
Remove `PredicateKind::ClosureKind`
We don't need the `ClosureKind` predicate kind -- instead, `Fn`-family trait goals are left as ambiguous, and we only need to make progress on `FnOnce` projection goals for inference purposes.
This is similar to how we do confirmation of `Fn`-family trait and projection goals in the new trait solver, which also doesn't use the `ClosureKind` predicate.
Some hacky logic is added in the second commit so that we can keep the error messages the same.
Remove `-Zperf-stats`.
The included measurements have varied over the years. At one point there were quite a few more, but #49558 deleted a lot that were no longer used. Today there's just four, and it's a motley collection that doesn't seem particularly valuable.
I think it has been well and truly subsumed by self-profiling, which collects way more data.
r? `@wesleywiser`
