This alters the diagnostics a bit, as the trait method is still stable.
The only thing this check does is ensure that compilation fails if a
trait implementation is declared const-stable.
Rather than deferring to const eval for checking if a trait is const, we
now check up-front. This allows the error to be emitted earlier, notably
at the same time as other stability checks.
Also included in this commit is a change of the default const stability
level to UNstable. Previously, an item that was `const` but did not
explicitly state it was unstable was implicitly stable.
Remove libstd's calls to `C-unwind` foreign functions
Remove all libstd and its dependencies' usage of `extern "C-unwind"`.
This is a prerequiste of a WIP PR which will forbid libraries calling `extern "C-unwind"` functions to be compiled in `-Cpanic=unwind` and linked against `panic_abort` (this restriction is necessary to address soundness bug #96926).
Cargo will ensure all crates are compiled with the same `-Cpanic` but the std is only compiled `-Cpanic=unwind` but needs the ability to be linked into `-Cpanic=abort`.
Currently there are two places where `C-unwind` is used in libstd:
* `__rust_start_panic` is used for interfacing to the panic runtime. This could be `extern "Rust"`
* `_{rdl,rg}_oom`: a shim `__rust_alloc_error_handler` will be generated by codegen to call into one of these; they can also be `extern "Rust"` (in fact, the generated shim is used as `extern "Rust"`, so I am not even sure why these are not, probably because they used to `extern "C"` and was changed to `extern "C-unwind"` when we allow alloc error hooks to unwind, but they really should just be using Rust ABI).
For dependencies, there is only one `extern "C-unwind"` function call, in `unwind` crate. This can be expressed as a re-export.
More dicussions can be seen in the Zulip thread: https://rust-lang.zulipchat.com/#narrow/stream/210922-project-ffi-unwind/topic/soundness.20in.20mixed.20panic.20mode
`@rustbot` label: T-libs F-c_unwind
Move some settings DOM generation out of JS
The first commit reduce the JS size a bit by moving some DOM content generation into the HTML file directly.
The second commit is an update of the `browser-ui-test` version which improves `wait-for-*` command (if the element doesn't exist, it'll wait for it instead of failing).
r? ``@notriddle``
Switch CI bucket uploads to intelligent tiering
We currently upload approximately 166 GB/day into this bucket (estimate based on
duration of storage and total current size). My estimate is that this change
should decrease our costs (which are currently in credits) and is in the worst
case (if all objects are brought into hot storage due to unanticipated frequent
access) only going to add an additional ~$4 to the monthly bill. If access is
rare (as expected) to most objects then we expect to save approximately
~$350/month (after this change takes full effect in ~168 days).
r? ``@pietroalbini``
Permit `asm_const` and `asm_sym` to reference generic params
Related #96557
These constructs will be allowed:
```rust
fn foofoo<const N: usize>() {}
unsafe fn foo<const N: usize>() {
asm!("/* {0} */", const N);
asm!("/* {0} */", const N + 1);
asm!("/* {0} */", sym foofoo::<N>);
}
fn barbar<T>() {}
unsafe fn bar<T>() {
asm!("/* {0} */", const std::mem::size_of::<T>());
asm!("/* {0} */", const std::mem::size_of::<(T, T)>());
asm!("/* {0} */", sym barbar::<T>);
asm!("/* {0} */", sym barbar::<(T, T)>);
}
```
`@Amanieu,` I didn't switch inline asms to use `DefKind::InlineAsm`, as I see little value doing that; given that no type inference is needed, it will only make typecking slower and more complex but will have no real gains. I did switch them to follow the same code path as inline asm during symbol resolution, though.
The `error: unconstrained generic constant` you mentioned in #76001 is due to the fact that `to_const` will actually add a wfness obligation to the constant, which we don't need for `asm_const`, so I have that removed.
`@rustbot` label: +A-inline-assembly +F-asm
--remap-path-prefix: Fix duplicated path components in debuginfo
This PR fixes an issue with `--remap-path-prefix` where path components could appear twice in the remapped version of the path (e.g. https://github.com/rust-lang/rust/issues/78479). The underlying problem was that `--remap-path-prefix` is often used to map an absolute path to something that looks like a relative path, e.g.:
```
--remap-path-prefix=/home/calvin/.cargo/registry/src/github.com-1ecc6299db9ec823=crates.io",
```
and relative paths in debuginfo are interpreted as being relative to the compilation directory. So if Cargo invokes the compiler with `/home/calvin/.cargo/registry/src/github.com-1ecc6299db9ec823/some_crate-0.1.0/src/lib.rs` as input and `/home/calvin/.cargo/registry/src/github.com-1ecc6299db9ec823/some_crate-0.1.0` as the compiler's working directory, then debuginfo will state that the working directory was `crates.io/some_crate-0.1.0` and the file is question was `crates.io/some_crate-0.1.0/src/lib.rs`, which combined gives the path:
```
crates.io/some_crate-0.1.0/crates.io/some_crate-0.1.0/src/lib.rs
```
With this PR the compiler will detect this situation and set up debuginfo in LLVM in a way that makes it strip the duplicated path components when emitting DWARF.
The PR also extracts the logic for making remapped paths absolute into a common helper function that is now used by debuginfo too (instead of just during crate metadata generation).
Add PID to PGO profile data filename
After experimenting with PGO, it looks like the generated profile data files can be sometimes overwritten if there is a race condition, because multiple `rustc` processes are usually invoked in parallel by `cargo`. Adding the PID to the resulting profile filename pattern makes sure that the profiles will be stored in separate files.
This generates ~20 GiB more space on disk on the CI run, but that seems harmless (?). Merging the profiles is not a bottleneck, the perf. run took the same amount of time as usually (~1h 24m).
r? `@lqd`
Clean fix for #96223
Okay, so here we are (hopefully) 👍Closes#96223
Thanks a lot to `@jackh726` for your help and explanation 🙏
- Modified `InferCtxt::mk_trait_obligation_with_new_self_ty` to take as argument a `Binder<(TraitPredicate, Ty)>` instead of a `Binder<TraitPredicate>` and a separate `Ty` with no bound vars.
- Modified all call places to avoid calling `Binder::no_bounds_var` or `Binder::skip_binder` when it is not safe.
r? `@jackh726`
Make HashMap fall back to RtlGenRandom if BCryptGenRandom fails
With PR #84096, Rust `std::collections::hash_map::RandomState` changed from using `RtlGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom)) to `BCryptGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom)) as its source of secure randomness after much discussion ([here](https://github.com/rust-random/getrandom/issues/65#issuecomment-753634074), among other places).
Unfortunately, after that PR landed, Mozilla Firefox started experiencing fairly-rare crashes during startup while attempting to initialize the `env_logger` crate. ([docs for env_logger](https://docs.rs/env_logger/latest/env_logger/)) The root issue is that on some machines, `BCryptGenRandom()` will fail with an `Access is denied. (os error 5)` error message. ([Bugzilla issue 1754490](https://bugzilla.mozilla.org/show_bug.cgi?id=1754490)) (Discussion in issue #94098)
Note that this is happening upon startup of Firefox's unsandboxed Main Process, so this behavior is different and separate from previous issues ([like this](https://bugzilla.mozilla.org/show_bug.cgi?id=1746254)) where BCrypt DLLs were blocked by process sandboxing. In the case of sandboxing, we knew we were doing something abnormal and expected that we'd have to resort to abnormal measures to make it work.
However, in this case we are in a regular unsandboxed process just trying to initialize `env_logger` and getting a panic. We suspect that this may be caused by a virus scanner or some other security software blocking the loading of the BCrypt DLLs, but we're not completely sure as we haven't been able to replicate locally.
It is also possible that Firefox is not the only software affected by this; we just may be one of the pieces of Rust software that has the telemetry and crash reporting necessary to catch it.
I have read some of the historical discussion around using `BCryptGenRandom()` in Rust code, and I respect the decision that was made and agree that it was a good course of action, so I'm not trying to open a discussion about a return to `RtlGenRandom()`. Instead, I'd like to suggest that perhaps we use `RtlGenRandom()` as a "fallback RNG" in the case that BCrypt doesn't work.
This pull request implements this fallback behavior. I believe this would improve the robustness of this essential data structure within the standard library, and I see only 2 potential drawbacks:
1. Slight added overhead: It should be quite minimal though. The first call to `sys::rand::hashmap_random_keys()` will incur a bit of initialization overhead, and every call after will incur roughly 2 non-atomic global reads and 2 easily predictable branches. Both should be negligible compared to the actual cost of generating secure random numbers
2. `RtlGenRandom()` is deprecated by Microsoft: Technically true, but as mentioned in [this comment on GoLang](https://github.com/golang/go/issues/33542#issuecomment-626124873), this API is ubiquitous in Windows software and actually removing it would break lots of things. Also, Firefox uses it already in [our C++ code](https://searchfox.org/mozilla-central/rev/5f88c1d6977e03e22d3420d0cdf8ad0113c2eb31/mfbt/RandomNum.cpp#25), and [Chromium uses it in their code as well](https://source.chromium.org/chromium/chromium/src/+/main:base/rand_util_win.cc) (which transitively means that Microsoft uses it in their own web browser, Edge). If there did come a time when Microsoft truly removes this API, it should be easy enough for Rust to simply remove the fallback in the code I've added here
Mention traits and types involved in unstable trait upcasting
Fixes#95972 by printing the traits being upcasted and the types being coerced that cause that upcasting...
---
the poor span mentioned in the original issue has nothing to do with trait upcasting diagnostic here...
> The original example I had that made me run into this issue had an even longer expression there (multiple chained
iterator methods) which just got all highlighted as one big block saying "somewhere here trait coercion is used and it's not allowed".
I don't think I can solve that issue in general without fixing the ObligationCauseCode and span that gets passed into Coerce.
Suggest dereferencing non-lval mutable reference on assignment
1. Adds deref suggestions for LHS of assignment (or assign-binop) when it implements `DerefMut`
2. Fixes missing deref suggestions for LHS when it isn't a place expr
Fixes#46276Fixes#93980
interpret/validity: reject references to uninhabited types
According to https://doc.rust-lang.org/reference/behavior-considered-undefined.html, this is definitely UB. And we can check this without actually looking up anything in memory, we just need the reference value and its type, making this a great candidate for a validity invariant IMO and my favorite resolution of https://github.com/rust-lang/unsafe-code-guidelines/issues/77.
With this PR, Miri with `-Zmiri-check-number-validity` implements all my preferred options for what the validity invariants of our types could be. :)
CTFE has been doing recursive checking anyway, so this is backwards compatible but might change the error output. I will submit a PR with the new Miri tests soon.
r? `@oli-obk`
Add tmm_reg clobbers
This adds support for naming the 8 tile registers from intel AMX as clobbers from `asm!` invocations on x86_64 (only). It does not add the registers as input or output operands.
