…y-namespace, r=compiler-errors

Resolve associated item bindings by namespace

This is the 3rd commit split off from rust-lang#118360 with tests reblessed (they no longer contain duplicated diags which were caused by 4c0addc) & slightly adapted (removed supertraits from a UI test, cc rust-lang#118040).

> * Resolve all assoc item bindings (type, const, fn (feature `return_type_notation`)) by namespace instead of trying to resolve a type first (in the non-RTN case) and falling back to consts afterwards. This is consistent with RTN. E.g., for `Tr<K = {…}>` we now always try to look up assoc consts (this extends to supertrait bounds). This gets rid of assoc tys shadowing assoc consts in assoc item bindings which is undesirable & inconsistent (types and consts live in different namespaces after all)
> * Consolidate the resolution of assoc {ty, const} bindings and RTN (dedup, better diags for RTN)
> * Fix assoc consts being labeled as assoc *types* in several diagnostics
> * Make a bunch of diagnostics translatable

Fixes rust-lang#112560 (error → pass).

As discussed
r? `@compiler-errors`

---

**Addendum**: What I call “associated item bindings” are commonly referred to as “type bindings” for historical reasons. Nowadays, “type bindings” include assoc type bindings, assoc const bindings and RTN (return type notation) which is why I prefer not to use this outdated term.

…li-obk,cjgillot

Fix type resolution of associated const equality bounds (take 2)

Instead of trying to re-resolve the type of assoc const bindings inside the `type_of` query impl in an incomplete manner, transfer the already (correctly) resolved type from `add_predicates_for_ast_type_binding` to `type_of`/`anon_type_of` through query feeding.

---

Together with rust-lang#118668 (merged) and rust-lang#121258, this supersedes rust-lang#118360.
Fixes rust-lang#118040.

r? `@ghost`

…li-obk,cjgillot

Fix type resolution of associated const equality bounds (take 2)

Instead of trying to re-resolve the type of assoc const bindings inside the `type_of` query impl in an incomplete manner, transfer the already (correctly) resolved type from `add_predicates_for_ast_type_binding` to `type_of`/`anon_type_of` through query feeding.

---

Together with rust-lang#118668 (merged) and rust-lang#121258, this supersedes rust-lang#118360.
Fixes rust-lang#118040.

r? ``@ghost``

Rollup merge of rust-lang#119385 - fmease:assoc-const-eq-fixes-2, r=oli-obk,cjgillot

Fix type resolution of associated const equality bounds (take 2)

Instead of trying to re-resolve the type of assoc const bindings inside the `type_of` query impl in an incomplete manner, transfer the already (correctly) resolved type from `add_predicates_for_ast_type_binding` to `type_of`/`anon_type_of` through query feeding.

---

Together with rust-lang#118668 (merged) and rust-lang#121258, this supersedes rust-lang#118360.
Fixes rust-lang#118040.

r? ``@ghost``

…y-generic-tys, r=compiler-errors

Reject overly generic assoc const binding types

Split off from rust-lang#119385 to make rust-lang#119385 easier to review.

---

In the *instantiated* type of assoc const bindings

1. reject **early-bound generic params**
   * Provide a rich error message instead of ICE'ing ([rust-lang#108271](rust-lang#108271)).
   * This is a temporary and semi-artificial restriction until the arrival of *generic const generics*.
   * It's quite possible that rustc could already perfectly support this subset of generic const generics if we just removed some checks (some `.no_bound_vars().expect(…)`) but even if that was the case, I'd rather gate it behind a new feature flag. Reporting an error instead of ICE'ing is a good first step towards an eventual feature gate error.
2. reject **escaping late-bound generic params**
   * They lead to ICEs before & I'm pretty sure that they remain incorrect even in a world with *generic const generics*

---

Together with rust-lang#118668 & rust-lang#119385, this supersedes rust-lang#118360.
Fixes rust-lang#108271.

…y-generic-tys, r=compiler-errors

Reject overly generic assoc const binding types

Split off from rust-lang#119385 to make rust-lang#119385 easier to review.

---

In the *instantiated* type of assoc const bindings

1. reject **early-bound generic params**
   * Provide a rich error message instead of ICE'ing ([rust-lang#108271](rust-lang#108271)).
   * This is a temporary and semi-artificial restriction until the arrival of *generic const generics*.
   * It's quite possible that rustc could already perfectly support this subset of generic const generics if we just removed some checks (some `.no_bound_vars().expect(…)`) but even if that was the case, I'd rather gate it behind a new feature flag. Reporting an error instead of ICE'ing is a good first step towards an eventual feature gate error.
2. reject **escaping late-bound generic params**
   * They lead to ICEs before & I'm pretty sure that they remain incorrect even in a world with *generic const generics*

---

Together with rust-lang#118668 & rust-lang#119385, this supersedes rust-lang#118360.
Fixes rust-lang#108271.

…y-generic-tys, r=compiler-errors

Reject overly generic assoc const binding types

Split off from rust-lang#119385 to make rust-lang#119385 easier to review.

---

In the *instantiated* type of assoc const bindings

1. reject **early-bound generic params**
   * Provide a rich error message instead of ICE'ing ([rust-lang#108271](rust-lang#108271)).
   * This is a temporary and semi-artificial restriction until the arrival of *generic const generics*.
   * It's quite possible that rustc could already perfectly support this subset of generic const generics if we just removed some checks (some `.no_bound_vars().expect(…)`) but even if that was the case, I'd rather gate it behind a new feature flag. Reporting an error instead of ICE'ing is a good first step towards an eventual feature gate error.
2. reject **escaping late-bound generic params**
   * They lead to ICEs before & I'm pretty sure that they remain incorrect even in a world with *generic const generics*

---

Together with rust-lang#118668 & rust-lang#119385, this supersedes rust-lang#118360.
Fixes rust-lang#108271.

Rollup merge of rust-lang#121258 - fmease:assoc-const-eq-reject-overly-generic-tys, r=compiler-errors

Reject overly generic assoc const binding types

Split off from rust-lang#119385 to make rust-lang#119385 easier to review.

---

In the *instantiated* type of assoc const bindings

1. reject **early-bound generic params**
   * Provide a rich error message instead of ICE'ing ([rust-lang#108271](rust-lang#108271)).
   * This is a temporary and semi-artificial restriction until the arrival of *generic const generics*.
   * It's quite possible that rustc could already perfectly support this subset of generic const generics if we just removed some checks (some `.no_bound_vars().expect(…)`) but even if that was the case, I'd rather gate it behind a new feature flag. Reporting an error instead of ICE'ing is a good first step towards an eventual feature gate error.
2. reject **escaping late-bound generic params**
   * They lead to ICEs before & I'm pretty sure that they remain incorrect even in a world with *generic const generics*

---

Together with rust-lang#118668 & rust-lang#119385, this supersedes rust-lang#118360.
Fixes rust-lang#108271.