Remove support for `dyn*` from the compiler
This PR removes support for `dyn*` (https://github.com/rust-lang/rust/issues/102425), which are a currently un-RFC'd experiment that was opened a few years ago to explore a component that we thought was necessary for AFIDT (async fn in dyn trait).
It doesn't seem like we are going to need `dyn*` types -- even in an not-exposed-to-the-user way[^1] -- for us to implement AFIDT. Given that AFIDT was the original motivating purpose of `dyn*` types, I don't really see a compelling reason to have to maintain their implementation in the compiler.
[^1]: Compared to, e.g., generators whih are an unstable building block we use to implement stable syntax like `async {}`.
We've learned quite a lot from `dyn*`, but I think at this point its current behavior leads to more questions than answers. For example, `dyn*` support today remains somewhat fragile; it ICEs in many cases where the current "normal" `dyn Trait` types rely on their unsizedness for their vtable-based implementation to be sound I wouldn't be surprised if it's unsound in other ways, though I didn't play around with it too much. See the examples below.
```rust
#![feature(dyn_star)]
trait Foo {
fn hello(self);
}
impl Foo for usize {
fn hello(self) {
println!("hello, world");
}
}
fn main() {
let x: dyn* Foo = 1usize;
x.hello();
}
```
And:
```rust
#![feature(dyn_star)]
trait Trait {
type Out where Self: Sized;
}
fn main() {
let x: <dyn* Trait as Trait>::Out;
}
```
...and probably many more problems having to do with the intersection of dyn-compatibility and `Self: Sized` bounds that I was too lazy to look into like:
* GATs
* Methods with invalid signatures
* Associated consts
Generally, `dyn*` types also end up getting in the way of working with [normal `dyn` types](https://github.com/rust-lang/rust/issues/102425#issuecomment-1712604409) to an extent that IMO outweighs the benefit of experimentation.
I recognize that there are probably other, more creative usages of `dyn*` that are orthogonal to AFIDT. However, I think any work along those lines should first have to think through some of the more fundamental interactions between `dyn*` and dyn-compatibility before we think about reimplementing them in the type system.
---
I'm planning on removing the `DynKind` enum and the `PointerLike` built-in trait from the compiler after this PR lands.
Closesrust-lang/rust#102425.
cc `@eholk` `@rust-lang/lang` `@rust-lang/types`
Closesrust-lang/rust#116979.
Closesrust-lang/rust#119694.
Closesrust-lang/rust#134591.
Closesrust-lang/rust#104800.
Remove `ItemKind::descr` method
Follow-up of rust-lang/rust#143234.
After this PR is merged, it will remain two `descr` methods:
* `hir::GenericArg::descr`
* `hir::AssocItemConstraintKind::descr`
For both these enums, I don't think there is the right equivalent in `hir::DefKind` so unless I missed something, we can't remove these two methods because we can't convert these enums into `hir::DefKind`.
r? `@oli-obk`
Do not enable LLD by default in the dist profile
History of us building & shipping LLD for `dist` builds:
1) We used to unconditionally build & ship LLD in bootstrap
2) This was causing problems for people doing custom `dist` builds (https://rust-lang.zulipchat.com/#narrow/stream/326414-t-infra.2Fbootstrap/topic/MSVC.20Runtime.20mismatch.20when.20building.20LLD)
3) https://github.com/rust-lang/rust/pull/126701 made shipping of LLD optional, but to preserve previous behavior, it forcefully enabled `rust.lld = true` in the `dist` profile by default, and overwrote the default to `false` on our CI for external LLVM builds.
- This also didn't match the documentation of `rust.lld` in `bootstrap.example.toml`, which I previously missed.
4) However, since the external LLVM opt-out was only implemented for our CI, and not for all `dist` users, this started causing issues for people `dist`ing with external LLVM (https://github.com/rust-lang/rust/issues/143076). The problem is that the default shouldn't be "true", but "LLD is enabled when LLVM isn't external", but this is not possible to do only in TOML.
So this PR reverses the behavior. LLD is not enabled by default in `dist` anymore. We switch our CI to *opt into* disting LLD, unless an external LLVM is used. External `dist` users can still opt into enabling LLD, but if they do so while also using external LLVM, they will now get a [hard error](https://github.com/rust-lang/rust/pull/143175).
r? `@jieyouxu`
try-job: `x86_64-mingw*`
try-job: dist-x86_64-linux
[COMPILETEST-UNTANGLE 2/N] Make some compiletest errors/warnings/help more visually obvious
This PR makes some compiletest errors/warnings/help more visually obvious. Note that this is only intended to help visually -- the error handling in compiletest is still a mess.
r? ghost
Upgrade dependencies in run-make-support
The main purpose of this is to upgrade `object` and `gimli`, which will allow us to drop outdated versions once backtrace also updates. The only semver breakage in `object`'s is in `elf::R_RISCV_GNU_*` and `pe::IMAGE_WEAK_EXTERN_*` constants, as well as Mach-O dyld, which don't appear to be used here. `gimli` is similar, there is only minor breakage related to dyld.
These version upgrades were also done in the library.
`bstr`, `similar`, and `regex` are also upgraded to the latest minor version here to match what the lockfile already uses. The `regex` comment about `memchr` version hasn't been relevant to this lockfile since e95d15a115 ("Pin memchr to 2.5.0 in the library rather than rustc_ast") and is no longer relevant in the library lockfile either.
Object Changelog: https://github.com/gimli-rs/object/blob/master/CHANGELOG.md#0370
Gimli changelog: https://github.com/gimli-rs/gimli/blob/master/CHANGELOG.md#0320
Introduce `ByteSymbol`
It's like `Symbol` but for byte strings. The interner is now used for both `Symbol` and `ByteSymbol`. E.g. if you intern `"dog"` and `b"dog"` you'll get a `Symbol` and a `ByteSymbol` with the same index and the characters will only be stored once.
The motivation for this is to eliminate the `Arc`s in `ast::LitKind`, to make `ast::LitKind` impl `Copy`, and to avoid the need to arena-allocate `ast::LitKind` in HIR. The latter change reduces peak memory by a non-trivial amount on literal-heavy benchmarks such as `deep-vector` and `tuple-stress`.
`Encoder`, `Decoder`, `SpanEncoder`, and `SpanDecoder` all get some changes so that they can handle normal strings and byte strings.
The main purpose of this is to upgrade `object` and `gimli`, which will
allow us to drop outdated versions once backtrace also updates.
The only semver breakage in `object`'s is in `elf::R_RISCV_GNU_*` and
`pe::IMAGE_WEAK_EXTERN_*` constants, as well as Mach-O dyld, which don't
appear to be used here. `gimli` is similar, there is only minor breakage
related to dyld.
These version upgrades were also done in the library.
`bstr`, `similar`, and `regex` are also upgraded to the latest minor
version here to match what the lockfile already uses. The `regex`
comment about `memchr` version hasn't been relevant to this lockfile
since e95d15a115 ("Pin memchr to 2.5.0 in the library rather than
rustc_ast") and is no longer relevant in the library lockfile either.
Object Changelog: https://github.com/gimli-rs/object/blob/master/CHANGELOG.md#0370
Gimli changelog: https://github.com/gimli-rs/gimli/blob/master/CHANGELOG.md#0320
Update books
## rust-lang/book
2 commits in 8a6d44e45b7b564eeb6bae30507e1fbac439d72d..ef1ce8f87a8b18feb1b6a9cf9a4939a79bde6795
2025-06-28 18:06:08 UTC to 2025-06-26 23:08:19 UTC
- Chapter 14 from tech review (rust-lang/book#4423)
- Chapter 13 from tech review (rust-lang/book#4421)
## rust-embedded/book
1 commits in 10fa1e084365f23f24ad0000df541923385b73b6..41f688a598a5022b749e23d37f3c524f6a0b28e1
2025-06-27 07:21:31 UTC to 2025-06-27 07:21:31 UTC
- Fix incorrect type for semihosted stdout stream rust-lang/rust#394 (rust-embedded/book#395)
## rust-lang/reference
4 commits in 50fc1628f36563958399123829c73755fa7a8421..e9fc99f107840813916f62e16b3f6d9556e1f2d8
2025-06-28 20:00:14 UTC to 2025-06-24 19:02:48 UTC
- fix: swap places for 2 words in associated-items.md sentence. (rust-lang/reference#1871)
- Add new temporary lifetime extension rule (rust-lang/reference#1813)
- Fix smart punctuation inside grammar terminals (rust-lang/reference#1869)
- Fix placement of codegen link definitions (rust-lang/reference#1868)
## rust-lang/rust-by-example
1 commits in 05c7d8bae65f23a1837430c5a19be129d414f5ec..288b4e4948add43f387cad35adc7b1c54ca6fe12
2025-06-25 12:35:59 UTC to 2025-06-25 12:35:59 UTC
- allow easy fixes (rust-lang/rust-by-example#1941)
[COMPILETEST-UNTANGLE 1/N] Move some some early config checks to the lib and move the compiletest binary
This is part of a patch series to untangle `compiletest` to hopefully nudge it towards being more maintainable.
This PR:
- Moves some early config checks (some warnings) to the compiletest library.
- Moves `src/main.rs` to `src/bin/main.rs` to make the separation (as in, compiletest's library component vs the tool binary component) more obvious.
r? ``@Kobzol`` (or reroll)
Use `tracing-forest` instead of `tracing-tree` for bootstrap tracing
I find the `tracing-forest` output easier to comprehend.
Note that this is not a strict improvement -- `tracing-forest` output contains some emojis and redundant log levels, but customizing it seems to be... non-trivial. Despite this, I still find `tracing-forest` easier to follow than `tracing-tree`, even when I tried to tune `tracing-tree` output.
### Preview
```bash
BOOTSTRAP_TRACING=debug ./x test library/std --dry-run
```
With `tracing-forest` (this PR), it looks like
With `tracing-tree` (before this PR), it looked like
r? `@Kobzol`
Make combining LLD with external LLVM config a hard error
Younger me made this only a warning in https://github.com/rust-lang/rust/pull/139853, because our post-dist tests were relying on this. But that was not a good idea, because there are a bunch of places in bootstrap that outright try to build LLD/copy LLD to sysroot when `lld_enabled` is true (rightfully so), which is causing issues (https://github.com/rust-lang/rust/issues/143076). Instead of piling more hacks, I'd like to just disallow this, and if we need to use a hack, do it only for our CI.
If this breaks the CI post-dist tests, I'll either add some special environment variable for it, or, as an alternative, make the error back into a warning, but also disable `lld_enabled` when this situation happens.
try-job: dist-x86_64-linux
Fixes: https://github.com/rust-lang/rust/pull/143175
give Pointer::into_parts a more scary name and offer a safer alternative
`into_parts` is a bit too innocent of a name for a somewhat subtle operation.
r? `@oli-obk`
Miri: handling of SNaN inputs in `f*::pow` operations
fixes [miri/#4286](https://github.com/rust-lang/miri/issues/4286) and related to rust-lang/rust#138062 and [miri/#4208](https://github.com/rust-lang/miri/issues/4208#issue-2879058184).
For the following cases of the powf or powi operations, Miri returns either `1.0` or an arbitrary `NaN`:
- `powf(SNaN, 0.0)`
- `powf(1.0, SNaN)`
- `powi(SNaN, 0)`
Also added a macro in `miri/tests/pass/float.rs` which conveniently checks if both are indeed returned from such an operation.
Made these changes in the rust repo so I could test against stdlib, since these were impacted some time ago and were fixed in rust-lang/rust#138062. Tested with:
```fish
env MIRIFLAGS=-Zmiri-many-seeds ./x miri --no-fail-fast std core coretests -- f32 f64
```
This was successful. This does take a while, so I recommend using `--no-doc` and separate use of `f32` or `f64`
The pr is somewhat split up into 3 main commits, which implement the cases described above. The first commit also introduces the macro, and the last commit is just a global refactor of some things.
r? `@RalfJung`
`tests/ui`: A New Order [13/N]
Some `tests/ui/` housekeeping, to trim down number of tests directly under `tests/ui/`. Part of rust-lang/rust#133895.
r? ```@jieyouxu```
It's like `Symbol` but for byte strings. The interner is now used for
both `Symbol` and `ByteSymbol`. E.g. if you intern `"dog"` and `b"dog"`
you'll get a `Symbol` and a `ByteSymbol` with the same index and the
characters will only be stored once.
The motivation for this is to eliminate the `Arc`s in `ast::LitKind`, to
make `ast::LitKind` impl `Copy`, and to avoid the need to arena-allocate
`ast::LitKind` in HIR. The latter change reduces peak memory by a
non-trivial amount on literal-heavy benchmarks such as `deep-vector` and
`tuple-stress`.
`Encoder`, `Decoder`, `SpanEncoder`, and `SpanDecoder` all get some
changes so that they can handle normal strings and byte strings.
This change does slow down compilation of programs that use
`include_bytes!` on large files, because the contents of those files are
now interned (hashed). This makes `include_bytes!` more similar to
`include_str!`, though `include_bytes!` contents still aren't escaped,
and hashing is still much cheaper than escaping.
