Fixes rust-lang#121593

…ethods

We already use `Instance` at declaration sites when available to glean
additional information about possible abstractions of the type in use.
This does the same when possible at callsites as well.

The primary purpose of this change is to allow CFI to alter how it
generates type information for indirect calls through `Virtual`
instances.

Additional trait bounds beyond the principal trait and its implications
are not possible in the vtable. This means that if a receiver is
`&dyn Foo + Send`, the function will only be expecting `&dyn Foo`.

This strips those auto traits off before CFI encoding.

Current `transform_ty` attempts to avoid cycles when normalizing
`#[repr(transparent)]` types to their interior, but runs afoul of this
pattern used in `self_cell`:

```
struct X<T> {
  x: u8,
  p: PhantomData<T>,
}

 #[repr(transparent)]
struct Y(X<Y>);
```

When attempting to normalize Y, it will still cycle indefinitely. By
using a types-visited list, this will instead get expanded exactly
one layer deep to X<Y>, and then stop, not attempting to normalize `Y`
any further.

… locals.

This should assist comprehending the size of coroutines.
In particular, whenever a future is suspended while awaiting another
future, the latter is given the special name `__awaitee`, and now the
type of the awaited future will be printed, allowing identifying
caller/callee — er, I mean, poller/pollee — relationships.

It would be possible to include the type name in more cases, but I
thought that that might be overly verbose (`print-type-sizes` is already
a lot of text) and ordinary named fields or variables are easier for
readers to discover the types of.

This gives us more confidence that the ICE was indeed fixed.

…mease

Mention Register Size in `#[warn(asm_sub_register)]`

Fixes rust-lang#121593

Displays the register size information obtained from `suggest_modifier()` and `default_modifier()`.

…=Nilstrieb

Rework rmake support library API

### Take 1: Strongly-typed API

Context: rust-lang#122448 (comment)

> My 2 cents: from my experience with writing similar "test DSLs", I would suggest to create these helpers as soon as possible in the process (basically the first time someone needs them, not only after N similar usages), and basically treat any imperative code in these high-level tests as a maintenance burden, basically making them as declarative as possible. Otherwise it might be a bit annoying to keep refactoring the tests later once such helpers are available.
>
> I would even discourage the arg method and create explicit methods for setting things like unpretty, the output file etc., but this might be more controversial, as it will make the invoked command-line arguments more opaque.

cc ``@Kobzol`` for the testing DSL suggestion.

Example:

```rs
let output = Rustc::new()
    .input_file("main.rs")
    .emit(&[EmitKind::Metadata])
    .extern_("stable", &stable_path)
    .output();
```

### Take 2: xshell-based macro API

Example:

```rs
let sh = Shell::new()?;
let stable_path = stable_path.to_string_lossy();
let output = cmd!(sh, "rustc main.rs --emit=metadata --extern stable={stable_path}").output()?;
```

### Take 3: Weakly-typed API with a few helper methods

```rs
let output = Rustc::new()
    .input("main.rs")
    .emit("metadata")
    .extern_("stable", &stable_path)
    .output();
```

…Mark-Simulacrum

Cancel `cargo update` job if there's no updates

Previously there were always updates so we didn't hit this. Since rust-lang#122489, this job runs on a more frequent schedule and causes errors if there have been no changes in that timespan.

This led to a weird error on rust-lang#122646 (comment) - because of this I've replaced the `exit 1`s here with `gh run cancel` so we don't have false 'failed' jobs in the logs.

…=oli-obk

Rename `hir::Local` into `hir::LetStmt`

Follow-up of rust-lang#122776.

As discussed on [zulip](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Improve.20naming.20of.20.60ExprKind.3A.3ALet.60.3F).

I made this change into a separate PR because I'm less sure about this change as is. For example, we have `visit_local` and `LocalSource` items. Is it fine to keep these two as is (I supposed it is but I prefer to ask) or not? Having `Node::Local(LetStmt)` makes things more explicit but is it going too far?

r? `@oli-obk`

…, r=workingjubilee

CFI: Support self_cell-like recursion

Current `transform_ty` attempts to avoid cycles when normalizing `#[repr(transparent)]` types to their interior, but runs afoul of this pattern used in `self_cell`:

```
struct X<T> {
  x: u8,
  p: PhantomData<T>,
}

 #[repr(transparent)]
struct Y(X<Y>);
```

When attempting to normalize Y, it will still cycle indefinitely. By using a types-visited list, this will instead get expanded exactly one layer deep to X<Y>, and then stop, not attempting to normalize `Y` any further.

This PR was split off from rust-lang#121962 as part of fixing the larger vtable compatibility issues.

r? `@workingjubilee`

…ngjubilee

CFI: Strip auto traits off Virtual calls

We already use `Instance` at declaration sites when available to glean additional information about possible abstractions of the type in use. This does the same when possible at callsites as well.

The primary purpose of this change is to allow CFI to alter how it generates type information for indirect calls through `Virtual` instances.

This is needed for the "separate machinery" version of my approach to the vtable issues (rust-lang#122573), because we need to respond differently to a `Virtual` call to the same type as a non-virtual call, specifically [stripping auto traits off the receiver's `Self`](rust-lang@54b15b0) because there isn't a separate vtable for `Foo` vs `Foo + Send`.

This would also make a more general underlying mechanism that could be used by rcvalle's [proposed drop detection / encoding](rust-lang@edcd1e2) if we end up using his approach, as we could condition out on the `def_id` in the CFI code rather than requiring the generating code to explicitly note whether it was calling drop.

… r=compiler-errors

Delay a bug if no RPITITs were found

Fixes rust-lang#122655. See the issue for context.

r? compiler-errors or compiler

…r=jhpratt

docs(sync): normalize dot in fn summaries

All other functions in e.g. [`Mutex`](https://doc.rust-lang.org/std/sync/struct.Mutex.html) have a dot at the end of their first doc line, except for the newly stabilized [`Mutex::clear_poison`](https://doc.rust-lang.org/std/sync/struct.Mutex.html#method.clear_poison) (and its friend [`RwLock::clear_poison`](https://doc.rust-lang.org/std/sync/struct.RwLock.html#method.clear_poison)).

This PR remedies that by adding a normalizing dot.

-Zprint-type-sizes: print the types of awaitees and unnamed coroutine locals.

This should assist comprehending the size of coroutines. In particular, whenever a future is suspended while awaiting another future, the latter is given the special name `__awaitee`, and now the type of the awaited future will be printed, allowing identifying caller/callee — er, I mean, poller/pollee — relationships.

It would be possible to include the type name in more cases, but I thought that that might be overly verbose (`print-type-sizes` is already a lot of text) and ordinary named fields or variables are easier for readers to discover the types of.

This change will also synergize with my other PR rust-lang#122923 which changes type printing to print the path of the `async fn` instead of the span.

Implementation note: I'm not sure if `Symbol::intern` is appropriate for this application, but it was the obvious way to not have to remove the `Copy` implementation from `FieldInfo`, or add a `'tcx` lifetime, while avoiding keeping a lot of possibly redundant strings in memory. I don't know what the proper tradeoff to make here is (though presumably it is not too important for a `-Z` debugging option).

…, r=workingjubilee

Change an ICE regression test to use the original reproducer

The ICE was fixed in PR rust-lang#122370, but the test used a different reproducer than the one originally reported. This PR changes it to the original one, giving us more confidence that the fix works.

Fixes rust-lang#122199