Auto merge of #70800 - Dylan-DPC:rollup-9jjoptp, r=Dylan-DPC
Rollup of 6 pull requests
Successful merges:
- #70635 (rustc_target: Some cleanup to `no_default_libraries`)
- #70748 (Do not disable field reordering on enums with big discriminant)
- #70752 (Add slice::fill)
- #70766 (use ManuallyDrop instead of forget inside collections)
- #70768 (macro_rules: `NtLifetime` cannot start with an identifier)
- #70783 (comment refers to removed type)
Rollup merge of #70752 - yoshuawuyts:slice_fill, r=dtolnay
Add slice::fill
Adds the `slice::fill` method to fill a slice with an item. This replaces manual for loops where items are copied one-by-one. This is a counterpart to C++20's [`std::fill`](https://en.cppreference.com/w/cpp/algorithm/fill) function.
When compiling in release mode, for `[u8]` and `[u16]` this method will optimize to a `memset(3)` call ([godbolt](https://godbolt.org/z/85El_c)). The initial implementation relies on LLVM's optimizer to make it as fast as possible for any given input. But as @jonas-schievink [pointed out](https://twitter.com/sheevink/status/1245756597453885442) this can later be optimized through specialization to guarantee it has a specific performance profile.
## Why now?
Conversations about adding `slice::fill` are not new. In fact, https://github.com/rust-lang/rfcs/issues/2067 was opened 3 years ago about this exact topic. However discussion stranded while discussing implementation details, and it's not seen much forward motion since.
In ["The Hunt for the Fastest Zero"](https://travisdowns.github.io/blog/2020/01/20/zero.html) Travis Downs provides disects C++'s `std::fill` performance profile on gcc, comparing it among others to `memset(3)`. Even though `memset(3)` outperforms `std::fill` in their tests, the author notes the following:
> That the optimization fails, perhaps unexpectedly, in some cases is unfortunate but it’s nice that you can fix it yourself. [...] Do we throw out modern C++ idioms, at least where performance matters, for example by replacing std::fill with memset? I don’t think so.
Much of the article focuses on how how to fix the performance of `std::fill` by providing specializations for specific input. In Rust we don't have any dedicated methods to fill slices with values, so it either needs to be optimized at the MIR layer, or more likely rely on LLVM's optimizer.
By adding a dedicated method for filling slices with values it opens up the ability for us to in the future guarantee that e.g. `Vec<u8>` will always optimize to `memset` even in debug mode. Or perhaps provide stronger guarantees about memory when zeroing values when a certain flag is passed. But regardless of that, it improves general ergonomics of working with slices by providing a dedicated method with documentation and examples.
## References
- [slice-fill prototype on docs.rs](https://docs.rs/slice-fill/1.0.1/slice_fill/)
- [The Hunt For The Fastest Zero](https://travisdowns.github.io/blog/2020/01/20/zero.html)
- [Safe memset for slices](https://github.com/rust-lang/rfcs/issues/2067)
- [C++20 std::fill](https://en.cppreference.com/w/cpp/algorithm/fill)
- [ASM output on Godbolt](https://godbolt.org/z/5-XU66)
Auto merge of #70272 - eddyb:type-of-impl-trait, r=nikomatsakis
typeck/type_of: let wfcheck handle generics in opaque types' substs.
I was working on #70164, and `type_of`'s handling of opaque types seemed to be, by far, the trickiest use of `Ty::walk`, but I believe it wasn't doing anything (see https://github.com/rust-lang/rust/pull/57896#discussion_r396064431 - I suspect, based on glancing at the PR discussion, that an early attempt was kept in, despite becoming just an overcomplicated way to do exactly the same as the previous simple type equality check).
I would've loved to remove `ResolvedOpaqueTy` (keep the `Ty` and lose the `Substs`), but it looks like the MIR borrowck part of the process needs that now, so it would've been added anyway since #57896, even if that PR hadn't happened.
<hr/>
In the process, I've moved the remaining substitution validation to `wfcheck`, which was already handling lifetimes, and kept only `delay_span_bug`s in `type_of`, as an insurance policy.
I've added tests for lifetime and const cases, they seem to be checked correctly now.
(and more uniform than they were in https://github.com/rust-lang/rust/issues/63063#issuecomment-602162804)
However, the quality of the errors is maybe a bit worse, and they don't trigger when there are other errors (not sure if this is due to compilation stop points or something more specific to one opaque type).
r? @nikomatsakis cc @matthewjasper @oli-obk @Aaron1011
Auto merge of #70136 - hermitcore:network_tcp, r=dtolnay
add basic IP support in HermitCore
- add initial version to support sockets
- use TcpStream as test case
- HermitCore uses smoltcp as IP stack for pure Rust applications
- further functionalities (e.g. UDP support) will be added step by step
- in principle, the current PR is a revision of #69404
LLVM supports placing the hash of source files inside the debug info.
This information can be used by a debugger to verify that the source code matches
the executable.
This change adds support for both hash algorithms supported by LLVM, MD5 and SHA1, controlled by a target option.
* DWARF only supports MD5
* LLVM IR supports MD5 and SHA1 (and SHA256 in LLVM 11).
* CodeView (.PDB) supports MD5, SHA1, and SHA256.
Fixes #68980.
Tracking issue: #70401
rustc dev guide PR with further details: https://github.com/rust-lang/rustc-dev-guide/pull/623
Auto merge of #70156 - michaelwoerister:incr-cgus, r=nikomatsakis
Make the rustc respect the `-C codegen-units` flag in incremental mode.
This PR implements (the as of yet unapproved) major change proposal at https://github.com/rust-lang/compiler-team/issues/245. See the description there for background and rationale.
The changes are pretty straightforward and should be easy to rebase if the proposal gets accepted at some point.
Auto merge of #70747 - Centril:rollup-2vx9bve, r=Centril
Rollup of 9 pull requests
Successful merges:
- #69860 (Use associated numeric consts in documentation)
- #70576 (Update the description of the ticket to point at RFC 1721)
- #70597 (Fix double-free and undefined behaviour in libstd::syn::unix::Thread::new)
- #70640 (Hide `task_context` when lowering body)
- #70641 (Remove duplicated code in trait selection)
- #70707 (Remove unused graphviz emitter)
- #70720 (Place TLS initializers with relocations in .tdata)
- #70735 (Clean up E0502 explanation)
- #70741 (Add test for #59023)
Rollup merge of #70597 - vakaras:thread_new_double_free_bug_fix, r=Amanieu
Fix double-free and undefined behaviour in libstd::syn::unix::Thread::new
While working on concurrency support for Miri, I found that the `libstd::syn::unix::Thread::new` method has two potential problems: double-free and undefined behaviour.
**Double-free** could occur if the following events happened (credit for pointing this out goes to @RalfJung):
1. The call to `pthread_create` successfully launched a new thread that executed to completion and deallocated `p`.
2. The call to `pthread_attr_destroy` returned a non-zero value causing the `assert_eq!` to panic.
3. Since `mem::forget(p)` was not yet executed, the destructor of `p` would be executed and cause a double-free.
As far as I understand, this code also violates the stacked-borrows aliasing rules and thus would result in **undefined behaviour** if these rules were adopted. The problem is that the ownership of `p` is passed to the newly created thread before the call to `mem::forget`. Since the call to `mem::forget` is still a call, it counts as a use of `p` and triggers UB.
This pull request changes the code to use `mem::ManuallyDrop` instead of `mem::forget`. As a consequence, in case of a panic, `p` would be potentially leaked, which while undesirable is probably better than double-free or undefined behaviour.
Rollup merge of #69860 - faern:use-assoc-int-consts, r=dtolnay
Use associated numeric consts in documentation
Now when the associated constants on int/float types are stabilized and the recommended way of accessing said constants (#68952). We can start using it in this repository, and recommend it via documentation example code.
This PR is the reincarnation of #67913 minus the actual adding + stabilization of said constants. (EDIT: Now it's only changing the documentation. So users will see the new consts, but we don't yet update the internal code)
Because of how fast bit rot happens to PRs that touch this many files, it does not try to replace 100% of the old usage of the constants in the entire repo, but a good chunk of them.
Auto merge of #70734 - Dylan-DPC:rollup-xmncatq, r=Dylan-DPC
Rollup of 6 pull requests
Successful merges:
- #70696 (Extend #69020 test to include reversed operand order.)
- #70706 (Minor cleanup in rustdoc --check-theme)
- #70725 (Avoid `.unwrap()`s on `.span_to_snippet(...)`s)
- #70728 (Minor doc improvements on `AllocRef`)
- #70730 (Fix link in task::Wake docs)
- #70731 (Minor follow-up after renaming librustc(_middle))
Rollup merge of #70730 - yoshuawuyts:fix-wake-docs-link, r=Dylan-DPC
Fix link in task::Wake docs
`task::Wake` was introduced in https://github.com/rust-lang/rust/pull/68700. While I was browsing the docs I noticed a link to `sync::Arc` wasn't resolving correctly. This patch fixes that. Thanks!
## Before
## Proposed
Rollup merge of #70706 - gizmondo:check-theme, r=GuillaumeGomez
Minor cleanup in rustdoc --check-theme
Expand and remove try_something macro. Since https://github.com/rust-lang/rust/commit/2f6226518bd5085896a0f27cfd3ea396367ecd50 there has been only one invocation.
Rollup merge of #70698 - nikomatsakis:x-py-json-output, r=Mark-Simulacrum
bootstrap: add `--json-output` for rust-analyzer
Motivation is that this allows us to customize rust-analyzer's "cargo watch" integration to run x.py. You simply have to set the command to run to be `x.py --json-output`
r? @Mark-Simulacrum -- feel free to make changes, this is quick and dirty for sure
Rollup merge of #70224 - GuillaumeGomez:clean-up-rustdoc-js-testers, r=Dylan-DPC
Clean up rustdoc js testers
I realized after the improvement made by @ollie27 on the rustdoc-js-tester that a lot of code was actually duplicated. This PR intends to remove this duplication, making it simpler to update in case of future main.js updates.
Auto merge of #70642 - eddyb:remap-sysroot-src, r=Mark-Simulacrum
Translate the virtual `/rustc/$hash` prefix back to a real directory.
Closes #53486 and fixes #53081, by undoing the remapping to `/rustc/$hash` on the fly, when appropriate (e.g. our testsuites, or user crates that depend on `libstd`), but not during the Rust build itself (as that could leak the absolute build directory into the artifacts, breaking deterministic builds).
Tested locally by setting `remap-debuginfo = true` in `config.toml`, which without these changes, was causing 56 tests to fail (see https://github.com/rust-lang/rust/issues/53081#issuecomment-606703215 for more details).
Auto merge of #70722 - Centril:rollup-ar4gn1x, r=Centril
Rollup of 7 pull requests
Successful merges:
- #70487 (Stabilize float::to_int_unchecked)
- #70595 (Remove unused discriminant reads from MIR bodies)
- #70691 (Improve docs in `AllocRef`)
- #70694 (Use Self over specific type in return position)
- #70700 (Expand on platform details of `include_xxx` macros)
- #70708 (Fix typo in u8::to_ascii_uppercase and u8::to_ascii_lowercase)
- #70716 (Unerase regions in infer_placeholder_type)
Rollup merge of #70700 - jrvidal:include-macro-paths, r=Dylan-DPC
Expand on platform details of `include_xxx` macros
This is a small detail that is not explicitly mentioned, but it left me scratching my head for a while until I looked into its implementation details. Maybe worth mentioning.
Rollup merge of #70487 - Mark-Simulacrum:float-unchecked-casts, r=SimonSapin
Stabilize float::to_int_unchecked
This renames and stabilizes unsafe floating point to integer casts, which are intended to be the substitute for the currently unsound `as` behavior, once that changes to safe-but-slower saturating casts. As such, I believe this also likely unblocks #10184 (our oldest I-unsound issue!), as once this rolls out to stable it would be far easier IMO to change the behavior of `as` to be safe by default.
This does not stabilize the trait or the associated method, as they are deemed internal implementation details (and consumers should not, generally, want to expose them, as in practice all callers likely know statically/without generics what the return type is).
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