rename ptr::from_exposed_addr -> ptr::with_exposed_provenance
As discussed on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/136281-t-opsem/topic/To.20expose.20or.20not.20to.20expose/near/427757066).
The old name, `from_exposed_addr`, makes little sense as it's not the address that is exposed, it's the provenance. (`ptr.expose_addr()` stays unchanged as we haven't found a better option yet. The intended interpretation is "expose the provenance and return the address".)
The new name nicely matches `ptr::without_provenance`.
Refactor stack overflow handling
Currently, every platform must implement a `Guard` that protects a thread from stack overflow. However, UNIX is the only platform that actually does so. Windows has a different mechanism for detecting stack overflow, while the other platforms don't detect it at all. Also, the UNIX stack overflow handling is split between `sys::pal::unix::stack_overflow`, which implements the signal handler, and `sys::pal::unix::thread`, which detects/installs guard pages.
This PR cleans this by getting rid of `Guard` and unifying UNIX stack overflow handling inside `stack_overflow` (commit 1). Therefore we can get rid of `sys_common::thread_info`, which stores `Guard` and the current `Thread` handle and move the `thread::current` TLS variable into `thread` (commit 2).
The second commit is not strictly speaking necessary. To keep the implementation clean, I've included it here, but if it causes too much noise, I can split it out without any trouble.
std:🧵 refine available_parallelism for solaris/illumos.
Rather than the system-wide available cpus fallback solution, we fetch the cpus bound to the current process.
Relax SeqCst ordering in standard library.
Every single SeqCst in the standard library is unnecessary. In all cases, Relaxed or Release+Acquire was sufficient.
As I [wrote](https://marabos.nl/atomics/memory-ordering.html#common-misconceptions) in my book on atomics:
> [..] when reading code, SeqCst basically tells the reader: "this operation depends on the total order of every single SeqCst operation in the program," which is an incredibly far-reaching claim. The same code would likely be easier to review and verify if it used weaker memory ordering instead, if possible. For example, Release effectively tells the reader: "this relates to an acquire operation on the same variable," which involves far fewer considerations when forming an understanding of the code.
>
> It is advisable to see SeqCst as a warning sign. Seeing it in the wild often means that either something complicated is going on, or simply that the author did not take the time to analyze their memory ordering related assumptions, both of which are reasons for extra scrutiny.
r? ````@Amanieu```` ````@joboet````
Use `UnsafeCell` for fast constant thread locals
This uses `UnsafeCell` instead of `static mut` for fast constant thread locals. This changes the type of the TLS shims to return `&UnsafeCell<T>` instead of `*mut T` which means they are always non-null so LLVM can optimize away the check for `Some` in `LocalKey::with` if `T` has no destructor.
LLVM is currently unable to do this optimization as we lose the fact that `__getit` always returns `Some` as it gets optimized to just returning the value of the TLS shim.
Bump windows-bindgen to 0.55.0
windows-bindgen is the crate used to generate std's Windows API bindings.
Not many changes for us, it's mostly just simplifying the generate code (e.g. no more `-> ()`). The one substantial change is some structs now use `i8` byte arrays instead of `u8`. However, this only impacts one test.
change std::process to drop supplementary groups based on CAP_SETGID
A trivial rebase of #95982
Should fix#39186 (from what I can tell)
Original description:
> Fixes#88716
>
> * Before this change, when a process was given a uid via `std::os::unix::process::CommandExt.uid`, there would be a `setgroups` call (when the process runs) to clear supplementary groups for the child **if the parent was root** (to remove potentially unwanted permissions).
> * After this change, supplementary groups are cleared if we have permission to do so, that is, if we have the CAP_SETGID capability.
>
> This new behavior was agreed upon in #88716 but there was a bit of uncertainty from `@Amanieu` here: [#88716 (comment)](https://github.com/rust-lang/rust/issues/88716#issuecomment-973366600)
>
> > I agree with this change, but is it really necessary to ignore an EPERM from setgroups? If you have permissions to change UID then you should also have permissions to change groups. I would feel more comfortable if we documented set_uid as requiring both UID and GID changing permissions.
>
> The way I've currently written it, we ignore an EPERM as that's what #88716 originally suggested. I'm not at all an expert in any of this so I'd appreciate feedback on whether that was the right way to go.
unix time module now return result
First try to fix#108277 without break anything.
if anyone who read this know tips to be able to check compilation for different target I could use some help. So far I installed many target with rustup but `./x check --all-targets` doesn't seem to use them.
TODO:
- [x] better error
- [ ] test, how ?
`@rustbot` label -S-waiting-on-author +S-waiting-on-review
The dead_code lint was previously eroneously missing this dead code.
Since this lint bug has been fixed, the unused field need
to be removed or marked as `#[allow(dead_code)]`.
These structures API is common to all platforms so the code cannot be
removed and is hence marked allow(dead_code).
The dead_code lint was previously eroneously missing this dead code.
Since this lint bug has been fixed, the unused field need
to be removed or marked as `#[allow(dead_code)]`.
Given the nature of this code, I don't feel confident removing the field
so it is only marked as allow(dead_code).
std support for wasm32 panic=unwind
Tracking issue: #118168
This adds std support for `-Cpanic=unwind` on wasm, and with it slightly more fleshed out rustc support. Now, the stable default is still panic=abort without exception-handling, but if you `-Zbuild-std` with `RUSTFLAGS=-Cpanic=unwind`, you get wasm exception-handling try/catch blocks in the binary:
```rust
#[no_mangle]
pub fn foo_bar(x: bool) -> *mut u8 {
let s = Box::<str>::from("hello");
maybe_panic(x);
Box::into_raw(s).cast()
}
#[inline(never)]
#[no_mangle]
fn maybe_panic(x: bool) {
if x {
panic!("AAAAA");
}
}
```
```wat
;; snip...
(try $label$5
(do
(call $maybe_panic
(local.get $0)
)
(br $label$1)
)
(catch_all
(global.set $__stack_pointer
(local.get $1)
)
(call $__rust_dealloc
(local.get $2)
(i32.const 5)
(i32.const 1)
)
(rethrow $label$5)
)
)
;; snip...
```
