Update `catch_unwind` doc comments for `c_unwind`
Updates `catch_unwind` doc comments to indicate that catching a foreign exception _will no longer_ be UB. Instead, there are two possible behaviors, though it is not specified which one an implementation will choose.
Nominated for t-lang to confirm that they are okay with making such a promise based on t-opsem FCP, or whether they would like to be included in the FCP.
Related: https://github.com/rust-lang/rust/issues/74990, https://github.com/rust-lang/rust/issues/115285, https://github.com/rust-lang/reference/pull/1226
Implement RFC3137 trim-paths sysroot changes - take 2
This PR is a continuation of https://github.com/rust-lang/rust/pull/118149. Nothing really changed, except for https://github.com/rust-lang/rust/pull/129408 which I was able to trigger locally.
Original description:
> Implement parts of #111540
>
> Right now, backtraces into sysroot always shows /rustc/$hash in diagnostics, e.g.
>
> ```
> thread 'main' panicked at 'hello world', map-panic.rs:2:50
> stack backtrace:
> 0: std::panicking::begin_panic
> at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/std/src/panicking.rs:616:12
> 1: map_panic::main::{{closure}}
> at ./map-panic.rs:2:50
> 2: core::option::Option<T>::map
> at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/option.rs:929:29
> 3: map_panic::main
> at ./map-panic.rs:2:30
> 4: core::ops::function::FnOnce::call_once
> at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/ops/function.rs:248:5
> note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
> ```
>
> [RFC 3127 said](https://rust-lang.github.io/rfcs/3127-trim-paths.html#changing-handling-of-sysroot-path-in-rustc)
>
> > We want to change this behaviour such that, when rust-src source files can be discovered, the virtual path is discarded and therefore the local path will be embedded, unless there is a --remap-path-prefix that causes this local path to be remapped in the usual way.
>
> This PR implements this behaviour. When `rust-src` is present at compile time, rustc replaces /rustc/$hash with a real path into local rust-src with best effort. To sanitise this, users must explicitly supply `--remap-path-prefix=<path to rust-src>=foo`.
cc `@cbeuw`
Fix#105907Fix#85463
try-job: dist-x86_64-linux
try-job: x86_64-msvc
try-job: dist-x86_64-msvc
try-job: armhf-gnu
Improve autovectorization of to_lowercase / to_uppercase functions
Refactor the code in the `convert_while_ascii` helper function to make it more suitable for auto-vectorization and also process the full ascii prefix of the string. The generic case conversion logic will only be invoked starting from the first non-ascii character.
The runtime on a microbenchmark with a small ascii-only input decreases from ~55ns to ~18ns per iteration. The new implementation also reduces the amount of unsafe code and encapsulates all unsafe inside the helper function.
Fixes#123712
Enable `f16` tests on platforms that were missing conversion symbols
The only requirement for `f16` support, aside from LLVM not crashing and no ABI issues, is that symbols to convert to and from `f32` are available. Since the update to compiler-builtins in https://github.com/rust-lang/rust/pull/125016, we now provide these on all platforms.
This also enables `f16` math since there are no further requirements.
Still excluded are platforms for which LLVM emits infinitely-recursing code.
try-job: arm-android
try-job: test-various
try-job: x86_64-fuchsia
This is done to cover the path of the test it-self as it may not live
on the same root directory as {{rust-src-base}}, which can be the case
if {{rust-src-base}} is coming from a extracted dist build (cc opt-dist)
in case the real paths into the libstd/libcore are located inside the
the build directory, maybe because it's coming from an extracted dist
component in the build dir (cc opt-dist)
Rollup of 5 pull requests
Successful merges:
- #128778 (atomics: allow atomic and non-atomic reads to race)
- #130918 (simplify LLVM submodule handling)
- #130960 (Only add an automatic SONAME for Rust dylibs)
- #130973 (compiletest: rename "runtest/crash.rs" to "runtest/crashes.rs" to be in line with the test directory)
- #130976 (remove couple redundant clones)
r? `@ghost`
`@rustbot` modify labels: rollup
Only add an automatic SONAME for Rust dylibs
#126094 added an automatic relative `SONAME` to all dynamic libraries, but it was really only needed for Rust `--crate-type="dylib"`. In Fedora, it was a surprise to see `SONAME` on `"cdylib"` libraries like Python modules, especially because that generates an undesirable RPM `Provides`. We can instead add a `SONAME` just for Rust dylibs by passing the crate-type argument farther.
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=2314879
atomics: allow atomic and non-atomic reads to race
We currently define our atomics in terms of C++ `atomic_ref`. That has the unfortunate side-effect of making it UB for an atomic and a non-atomic read to race (concretely, [this code](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=d1a743774e60923db33def7fe314d754) has UB). There's really no good reason for this, all the academic models of the C++ memory model I am aware of allow this -- C++ just disallows this because of their insistence on an "object model" with typed memory, where `atomic_ref` temporarily creates an "atomic object" that may not be accesses via regular non-atomic operations.
So instead of tying our operations to `atomic_ref`, let us tie them directly to the underlying C++ memory model. I am not sure what is the best way to phrase this, so here's a first attempt.
We also carve out an exception from the "no mixed-size atomic accesses" rule to permit mixed-size atomic reads -- given that we permit mixed-size non-atomic reads, it seems odd that this would be disallowed for atomic reads. However, when an atomic write races with any other atomic operation, they must use the same size.
With this change, it is finally the case that every non-atomic access can be replaced by an atomic access without introducing UB.
Cc `@rust-lang/opsem` `@chorman0773` `@m-ou-se` `@WaffleLapkin` `@Amanieu`
Fixes https://github.com/rust-lang/unsafe-code-guidelines/issues/483
add tests for validity of Box with custom allocator
Ensure that the validity visitor visits both parts of a box with custom allocator using the right types.
Rename a few tests to make tidy happier
A somewhat random smattering of tests that I have recently looked at, and thus had cause to research and write down the reason for their existence.
Allow instantiating trait object binder in ptr-to-ptr casts
For unsizing coercions between trait objects with the same principal, we already allow instantiating the for binder. For example, coercing `Box<dyn for<'a> Trait<'a>` to `Box<dyn Trait<'static>>` is allowed.
Since ptr-to-ptr casts will insert an unsizing coercion before the cast if possible, this has the consequence that the following compiles already:
```rust
// This compiles today.
fn cast<'b>(x: *mut dyn for<'a> Trait<'a>) -> *mut dyn Trait<'b> {
// lowered as (roughly)
// tmp: *mut dyn Trait<'?0> = Unsize(x) // requires dyn for<'a> Trait<'a> <: dyn Trait<'?0>
// ret: *mut dyn Trait<'b> = PtrToPtr(tmp) // requires dyn Trait<'?0> == dyn Trait<'b>
x as _
}
```
However, if no unsizing coercion is inserted then this currently fails to compile as one type is more general than the other. This PR will allow this code to compile, too, by changing ptr-to-ptr casts of pointers with vtable metadata to use sutyping instead of type equality.
```rust
// This will compile after this PR.
fn cast<'b>(x: *mut dyn for<'a> Trait<'a>) -> *mut Wrapper<dyn Trait<'b>> {
// lowered as (roughly)
// no Unsize here!
// ret: *mut Wrapper<dyn Trait<'b>> = PtrToPtr(x) // requires dyn for<'a> Trait<'a> == dyn Trait<'b>
x as _
}
```
Note that it is already possible to work around the current restrictions and make the code compile before this PR by splitting the cast in two, so this shouldn't allow a new class of programs to compile:
```rust
// Workaround that compiles today.
fn cast<'b>(x: *mut dyn for<'a> Trait<'a>) -> *mut Wrapper<dyn Trait<'b>> {
x as *mut dyn Trait<'_> as _
}
```
r? `@compiler-errors`
cc `@WaffleLapkin`
Revert space-saving operations
The "all of our artifacts" `mv` seems like it may save enough space to matter sometimes, since it can range up to a gigabyte of difference, if memory serves. For the rest, I think we're good.
try-job: dist-aarch64-apple
rustdoc: update `ProcMacro` docs section on helper attributes
I believe the mention of attribute macros in the section on proc macro helper attributes is erroneous. As far as I can tell, attribute macros cannot define helper attributes.
The following attribute macro is not valid (fails to build), no matter how I try to define (or skip defining) the helpers:
```rust
#[proc_macro_attribute(attributes(helper))]
pub fn attribute_helpers(_attr: TokenStream, item: TokenStream) -> TokenStream {
item
}
```
The [language reference](https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros) also doesn't seem to mention attribute macro helpers. The helpers subsection is inside the section on derive macros.
Make clashing_extern_declarations considering generic args for ADT field
In following example, G<u16> should be recognized as different from G<u32> :
```rust
#[repr(C)] pub struct G<T> { g: [T; 4] }
pub mod x { extern "C" { pub fn g(_: super::G<u16>); } }
pub mod y { extern "C" { pub fn g(_: super::G<u32>); } }
```
fixes#130851
