Clarify licensing situation of MPSC and SPSC queue
Originally, these two files were licensed under the `BSD-2-Clause` license, as they were based off sample code on a blog licensing those snippets under that license:
* `library/std/src/sync/mpsc/mpsc_queue.rs`
* `library/std/src/sync/mpsc/spsc_queue.rs`
In 2017 though, the author of that blog agreed to relicense their code under the standard `MIT OR Apache-2.0` license in https://github.com/rust-lang/rust/pull/42149. This PR clarifies the situation in the files by expanding the comment at the top of the file.
r? ``@pnkfelix``
Fix `const_fn_trait_ref_impl`, add test for it
#99943 broke `#[feature(const_fn_trait_ref_impl)]`, this PR fixes this and adds a test for it.
r? ````@fee1-dead````
run alloc benchmarks in Miri and fix UB
Miri since recently has a "fake monotonic clock" that works even with isolation. Its measurements are not very meaningful but it means we can run these benches and check them for UB.
And that's a good thing since there was UB here: fixes https://github.com/rust-lang/rust/issues/104096.
r? ``@thomcc``
disable btree size tests on Miri
Seems fine not to run these in Miri, they can't have UB anyway. And this lets us do layout randomization in Miri.
r? ``@thomcc``
Specialize `iter::ArrayChunks::fold` for TrustedRandomAccess iterators
```
OLD:
test iter::bench_trusted_random_access_chunks ... bench: 368 ns/iter (+/- 4)
NEW:
test iter::bench_trusted_random_access_chunks ... bench: 30 ns/iter (+/- 0)
```
The resulting assembly is similar to #103166 but the specialization kicks in under different (partially overlapping) conditions compared to that PR. They're complementary.
In principle a TRA-based specialization could be applied to all `ArrayChunks` methods, including `next()` as we do for `Zip` but that would have all the same hazards as the Zip specialization. Only doing it for `fold` is far less hazardous. The downside is that it only helps with internal, exhaustive iteration. I.e. `for _ in` or `try_fold` will not benefit.
Note that the regular, `try_fold`-based and the specialized `fold()` impl have observably slightly different behavior. Namely the specialized variant does not fetch the remainder elements from the underlying iterator. We do have a few other places in the standard library where beyond-the-end-of-iteration side-effects are being elided under some circumstances but not others.
Inspired by https://old.reddit.com/r/rust/comments/yaft60/zerocost_iterator_abstractionsnot_so_zerocost/
The type is unsafe and now exposed to the whole crate.
Document it properly and add an unsafe method so the
caller can make it visible that something unsafe is happening.
Implement `std::marker::Tuple`, use it in `extern "rust-call"` and `Fn`-family traits
Implements rust-lang/compiler-team#537
I made a few opinionated decisions in this implementation, specifically:
1. Enforcing `extern "rust-call"` on fn items during wfcheck,
2. Enforcing this for all functions (not just ones that have bodies),
3. Gating this `Tuple` marker trait behind its own feature, instead of grouping it into (e.g.) `unboxed_closures`.
Still needing to be done:
1. Enforce that `extern "rust-call"` `fn`-ptrs are well-formed only if they have 1/2 args and the second one implements `Tuple`. (Doing this would fix ICE in #66696.)
2. Deny all explicit/user `impl`s of the `Tuple` trait, kinda like `Sized`.
3. Fixing `Tuple` trait built-in impl for chalk, so that chalkification tests are un-broken.
Open questions:
1. Does this need t-lang or t-libs signoff?
Fixes#99820
fix a comment in UnsafeCell::new
There are several safe methods that access the inner value: `into_inner` has existed since forever and `get_mut` also exists since recently. So this comment seems just wrong. But `&self` methods return raw pointers and thus require unsafe code (though the methods themselves are still safe).
libtest: run all tests in their own thread, if supported by the host
This reverts the threading changes of https://github.com/rust-lang/rust/pull/56243, which made it so that with `-j1`, the test harness does not spawn any threads. Those changes were done to enable Miri to run the test harness, but Miri supports threads nowadays, so this is no longer needed. Using a thread for each test is useful because the thread's name can be set to the test's name which makes panic messages consistent between `-j1` and `-j2` runs and also a bit more readable.
I did not revert the HashMap changes of https://github.com/rust-lang/rust/pull/56243; using a deterministic map seems fine for the test harness and the more deterministic testing is the better.
Fixes https://github.com/rust-lang/rust/issues/59122
Fixes https://github.com/rust-lang/rust/issues/70492
After rust-lang/rust#101946 this completes the move to cfg-if 1.0 by:
* Updating getrandom 0.1.14->0.1.16
* Updating panic_abort, panic_unwind, and unwind to cfg-if 1.0
Rewrite implementation of `#[alloc_error_handler]`
The new implementation doesn't use weak lang items and instead changes `#[alloc_error_handler]` to an attribute macro just like `#[global_allocator]`.
The attribute will generate the `__rg_oom` function which is called by the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom` function is defined in any crate then the compiler shim will call `__rdl_oom` in the alloc crate which will simply panic.
This also fixes link errors with `-C link-dead-code` with `default_alloc_error_handler`: `__rg_oom` was previously defined in the alloc crate and would attempt to reference the `oom` lang item, even if it didn't exist. This worked as long as `__rg_oom` was excluded from linking since it was not called.
This is a prerequisite for the stabilization of `default_alloc_error_handler` (#102318).
Include both benchmarks and tests in the numbers given to `TeFiltered{,Out}`
Fixes#103794
`#[bench]` is broken on nightly without this, sadly. It apparently has no test coverage. In addition to manually testing, I've added a run-make smokecheck for this (which would have caught the issue), but it would be nice to have a better way to test, err, libtest. For now we should get this in ASAP IMO
The new implementation doesn't use weak lang items and instead changes
`#[alloc_error_handler]` to an attribute macro just like
`#[global_allocator]`.
The attribute will generate the `__rg_oom` function which is called by
the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom`
function is defined in any crate then the compiler shim will call
`__rdl_oom` in the alloc crate which will simply panic.
This also fixes link errors with `-C link-dead-code` with
`default_alloc_error_handler`: `__rg_oom` was previously defined in the
alloc crate and would attempt to reference the `oom` lang item, even if
it didn't exist. This worked as long as `__rg_oom` was excluded from
linking since it was not called.
This is a prerequisite for the stabilization of
`default_alloc_error_handler` (#102318).
