The first PR for rust-lang/compiler-team#606

This is just the move-and-rename, because it's plenty big-and-bitrotty already.  Future PRs will start using `FieldIdx` more broadly, and concomitantly removing `FieldIdx::new`s.

…olver

Use random `HashMap` keys on Hermit

Initializing the keys with random data provided by the libOS avoids HashDOS attacks and similar issues.

CC `@stlankes`

…ivate, r=lcnr

Make `EvalCtxt`'s `infcx` private

To better protect against people doing bad things with the inner `InferCtxt`

r? `@lcnr`

Suggest ..= when someone tries to create an overflowing range

Fixes rust-lang#109529

Do not consider elaborated projection predicates for objects in new solver

Object types have projection bounds which are elaborated during astconv. There's no need to do it again for projection goals, since that'll give us duplicate projection candidatesd that are distinct up to regions due to the fact that we canonicalize every region to a separate variable. See quick example below the break for a better explanation.

Discussed this with lcnr, and adding a stop-gap until we get something like intersection region constraints (or modify canonicalization to canonicalize identical regions to the same canonical regions) -- after which, this will hopefully not matter and may be removed.

r? `@lcnr`

---

See `tests/ui/traits/new-solver/more-object-bound.rs`:

Consider a goal: `<dyn Iter<'a, ()> as Iterator>::Item = &'a ()`.

After canonicalization: `<dyn Iter<'!0r, (), Item = '!1r ()> as Iterator>::Item == &!'2r ()`
* First object candidate comes from the item bound in the dyn's bounds itself, giving us `<dyn Iter<'!0r, (), Item = '?!r ()> as Iterator>::Item == &!'1r ()`. This gives us one region constraint: `!'1r == !'2r`.
* Second object candidate comes from elaborating the principal trait ref, gives us `<dyn Iter<'!0r, (), Item = '!1r ()> as Iterator>::Item == &!'0r ()`. This gives us one region constraint: `!'0r == !'2r`.
* Oops! Ambiguity!

…loc, r=fee1-dead

Remove ~const from alloc

There is currently an effort underway to stop using `~const Trait`, temporarily, so as to refactor the logic underlying const traits with relative ease. This means it has to go from the standard library, as well.

I have taken the initial step of just removing these impls from alloc, as removing them from core is a much more tangled task. In addition, all of these implementations are one more-or-less logically-connected group, so reverting their deconstification as a group seems like it will also be sensible.

r? `@fee1-dead`

…mpiler-errors

Lint against escape sequences in Fluent files

Fixes rust-lang#109686 by checking for `\n`, `\"` and `\'` in Fluent files. It might be useful to have a way to opt out of this check, but all messages with violations currently do seem to be incorrect.

Move `mir::Field` → `abi::FieldIdx`

The first PR for rust-lang/compiler-team#606

This is just the move-and-rename, because it's plenty big already.  Future PRs will start using `FieldIdx` more broadly, and concomitantly removing `FieldIdx::new`s.

…=notriddle

rustdoc: Don't strip crate module

Until we decide something for rust-lang#109695, rustdoc won't crash anymore because the crate folder doesn't exist.

r? `@notriddle`