Equate fn outputs when inferring RPITIT hidden types
When we are trying to infer the hidden types for RPITITs, we need to equate the output tys instead of just subtyping them. For example:
```rust
trait Foo { fn bar() -> impl Sized {} }
impl Foo for () { fn bar() -> &'static str { "" } }
```
If we just subtype the signatures `fn() -> &'static str <: fn() -> _#1t` (where `_#1t` is the variable we've used to infer `impl Sized`), we'll end up `&'static str <: _#1t`, which causes us to infer `_#1t = #'_#2r str`, where `'_#2r` is unconstrained, which gets fixed up to `ReEmpty`, and which is certainly not what we want.
I can't actually think of a way to make this fail to compile, because during borrowck we've already done the method probe, and so we just look at the `impl` method signature and see the `&'static str` any time we call `<() as Foo>::bar()`. But this _does_ cause the ICE [here](https://github.com/rust-lang/rust/pull/98559#issuecomment-1241891994) in `@jackh726's` "Remove ReEmpty" PR (#98559) to stop ICEing, because after that PR we were leaking unconstrained region variables into the typeck results.
r? types
The `<*const T>::guaranteed_*` methods now return an option for the unknown case
cc https://github.com/rust-lang/rust/issues/53020#issuecomment-1236932443
I chose `0` for "not equal" and `1` for "equal" and left `2` for the unknown case so backends can just forward to raw pointer equality and it works ✨
r? `@fee1-dead` or `@lcnr`
cc `@rust-lang/wg-const-eval`
Fix ICE report flags display.
#92310 made some changes to the ICE report that displays the rustc flags, but it introduced a bug where a flag like `-Z incremental-verify-ich=yes` was being treated as-if it was `-Cincremental`. This corrupted the output and made it confusing. The cause was using `starts_with` instead of properly splitting the option.
For example, with the command like `rustc foo.rs -Cincremental=/tmp/a -Zincremental-verify-ich=yes --crate-type lib` would previously look like:
```
note: compiler flags: -C incremental -Z incremental --crate-type lib
```
It now looks like:
```
note: compiler flags: -C incremental=[REDACTED] -Z incremental-verify-ich=yes --crate-type lib
```
I added a `[REDACTED]` marker for `-Cincremental` so it is a little less confusing that a value has been removed.
Fixes#101588
Stabilize raw-dylib for non-x86
This stabilizes the `raw-dylib` and `link_ordinal` features (#58713) for non-x86 architectures (i.e., `x86_64`, `aarch64` and `thumbv7a`):
* Marked the `raw_dylib` feature as `active`.
* Marked the `link_ordinal` attribute as `ungated`.
* Added new errors if either feature is used on x86 targets without the `raw_dylib` feature being enabled.
* Updated tests to only set the `raw_dylib` feature when building for x86.
Tweak future opaque ty pretty printing
1. The `Return` type of a generator doesn't need to be a lang item just for diagnostic printing of types
2. We shouldn't suppress the `Output = Ty` of a opaque future if the type is a int or float var.
Make `Debug` impl for `Term` useful
because `Term { ptr: 78942378998734298342, maker: PhantomData, }` does not excel at communicating the necessary information
Normalize before erasing late-bound regions in `equal_up_to_regions`
Normalize erasing regions **first**, before passing the type through a `BottomUpFolder` which erases late-bound regions too.
The root cause of this issue is due to 96d4137dee, which removes a `normalize_erasing_regions` that happens before this call to `equal_up_to_regions`. While reverting that commit might be a fix, I think it was suspicious to be erasing late-bound regions first _then_ normalizing types in the first place in `equal_up_to_regions`.
-----
I am tempted to ask the reviewer to review and `r+` this without a UI test, since the existing issues that I think this fixes are all incredibly difficult to minimize (anything hyper/warp related, given the nature of those libraries 😓) or impossible to reproduce locally (the miri test), namely:
* This recently reported issue with tokio + warp: #101430
* This issue from `@RalfJung` about Miri being broken: #101344
* This additional issue reported in a comment by `@tmandry` (issue with fuchsia + hyper): https://github.com/rust-lang/rust/issues/101344#issuecomment-1235974564
I have locally verified that the repro in #101430 is fixed with this PR, but after a couple of hours of attempting to minimize this error and either failing to actually repro the ICE, or being overwhelmed with the number of traits and functions I need to inline into a UI test, I have basically given up. Thoughts are appreciated on how best to handle this.
r? `@oli-obk` who is at the intersection of MIR and types-related stuff who may be able to give advice 😅
