This change introduces a new module to StableMIR named `abi` with
information from `rustc_target::abi` and `rustc_abi`, that allow users
to retrieve more low level information required to perform
bit-precise analysis.

The layout of a type can be retrieved via `Ty::layout`, and the instance
ABI can be retrieved via `Instance::fn_abi()`.

To properly handle errors while retrieve layout information, we had
to implement a few layout related traits.

We should expand the information in PassMode later.

In [100753], `IncorrectCguReuseType` accidentally stopped being emitted.
Begin emitting it again rather than just blindly dropping it, and adjust
tests accordingly.

[100753]: rust-lang@706452e#diff-048389738ddcbe0f9765291a29db1fed9a5f03693d4781cfb5aaa97ffb3c7f84

…mease

Add check for possible CStr literals in pre-2021

Fixes [rust-lang#118654](rust-lang#118654)

Adds information to errors caused by possible CStr literals in pre-2021.

The lexer separates `c"str"` into two tokens if the edition is less than 2021, which later causes an error when parsing. This error now has a more helpful message that directs them to information about editions. However, the user might also have written `c "str"` in a later edition, so to not confuse people who _are_ using a recent edition, I also added a note about whitespace.

We could probably figure out exactly which scenario has been encountered by examining spans and editions, but I figured it would be better not to overcomplicate the creation of the error too much.

This is my first code PR and I tried to follow existing conventions as much as possible, but I probably missed something, so let me know!

… r=michaelwoerister

rustc_codegen_ssa: Don't drop `IncorrectCguReuseType` , make `rustc_expected_cgu_reuse` attr work

In [100753], `IncorrectCguReuseType` accidentally stopped being emitted by removing `diag.span_err(...)`. Begin emitting it again rather than just blindly dropping it, and adjust tests accordingly.

We assume that there are no bugs and that the currently actual CGU reuse is correct. If there are bugs, they will be discovered and fixed eventually, and the tests will then be updated.

[100753]: rust-lang@706452e#diff-048389738ddcbe0f9765291a29db1fed9a5f03693d4781cfb5aaa97ffb3c7f84

Closes rust-lang#118972

-Znext-solver: adapt overflow rules to avoid breakage

Do not erase overflow constraints if they are from equating the impl header when normalizing[^1].

This should be the minimal change to not break crates depending on the old project behavior of "apply impl constraints while only lazily evaluating any nested goals".

Fixes rust-lang/trait-system-refactor-initiative#70, see https://hackmd.io/ATf4hN0NRY-w2LIVgeFsVg for the reasoning behind this.

Only keeping constraints on overflow for `normalize-to` goals as that's the only thing needed for backcompat. It also allows us to not track the origin of root obligations. The issue with root goals would be something like the following:

```rust
trait Foo {}
trait Bar {}

trait FooBar {}
impl<T: Foo + Bar> FooBar for T {}

// These two should behave the same, rn we can drop constraints for both,
// but if we don't drop `Misc` goals we would only drop the constraints for
// `FooBar` unless we track origins of root obligations.
fn func1<T: Foo + Bar>() {}
fn func2<T: FooBaz>() {}
```

[^1]: mostly, the actual rules are slightly different

r? ``@compiler-errors``

…-const-trait, r=fee1-dead

effects: fix a comment

r? fee1-dead or compiler

…rrors

Add function ABI and type layout to StableMIR

This change introduces a new module to StableMIR named `abi` with information from `rustc_target::abi` and `rustc_abi`, that allow users to retrieve more low level information required to perform bit-precise analysis.

The layout of a type can be retrieved via `Ty::layout`, and the instance ABI can be retrieved via `Instance::fn_abi()`.

To properly handle errors while retrieve layout information, we had to implement a few layout related traits.

r? ```@compiler-errors```

…eywiser

Add arm-none-eabi and armv7r-none-eabi platform-support documentation.

Mostly collecting existing information that's common to all arm-none-eabi targets and putting it in one file and adding a new file with specific details about armv7r.

subtype_predicate: remove unnecessary probe

There is no reason to probe here. The failure either results in an actual type error, in which cases the probe is useless, or it is used inside of evaluate, in which case we're already inside of the `fn evaluation_probe`, so it is also not necessary.