Move `select_unpredictable` to the `hint` module
There has been considerable discussion in both the ACP (rust-lang/libs-team#468) and tracking issue (#133962) about whether the `bool::select_unpredictable` method should be in `core::hint` instead.
I believe this is the right move for the following reasons:
- The documentation explicitly says that it is a hint, not a codegen guarantee.
- `bool` doesn't have a corresponding `select` method, and I don't think we should be adding one.
- This shouldn't be something that people reach for with auto-completion unless they specifically understand the interactions with branch prediction. Using conditional moves can easily make code *slower* by preventing the CPU from speculating past the condition due to the data dependency.
- Although currently `core::hint` only contains no-ops, this isn't a hard rule (for example `unreachable_unchecked` is a bit of a gray area). The documentation only status that the module contains "hints to compiler that affects how code should be emitted or optimized". This is consistent with what `select_unpredictable` does.
End all lines in src/stage0 with trailing newline
Most tools that process text files prefer if every line ends in \n. Text files without the last newline are aberrant and usually not what you want.
**Before:**
```console
$ cat src/stage0 src/stage0
dist_server=https://static.rust-lang.org
artifacts_server=https://ci-artifacts.rust-lang.org/rustc-builds
...
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.gz=986f6c594d37bcbd3833e053640ba8775f68d26a65c5618386654ef55d7b3542
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.xz=c0d9a88c30d2ab38ec3a11fabb5515ed9bc3ac1a8e35a438d68bf7ff82f6b843dist_server=https://static.rust-lang.org
artifacts_server=https://ci-artifacts.rust-lang.org/rustc-builds
...
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.gz=986f6c594d37bcbd3833e053640ba8775f68d26a65c5618386654ef55d7b3542
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.xz=c0d9a88c30d2ab38ec3a11fabb5515ed9bc3ac1a8e35a438d68bf7ff82f6b843$ ▌
```
**After:**
```console
$ cat src/stage0 src/stage0
dist_server=https://static.rust-lang.org
artifacts_server=https://ci-artifacts.rust-lang.org/rustc-builds
...
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.gz=986f6c594d37bcbd3833e053640ba8775f68d26a65c5618386654ef55d7b3542
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.xz=c0d9a88c30d2ab38ec3a11fabb5515ed9bc3ac1a8e35a438d68bf7ff82f6b843
dist_server=https://static.rust-lang.org
artifacts_server=https://ci-artifacts.rust-lang.org/rustc-builds
...
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.gz=986f6c594d37bcbd3833e053640ba8775f68d26a65c5618386654ef55d7b3542
dist/2025-04-02/rustc-nightly-x86_64-unknown-netbsd.tar.xz=c0d9a88c30d2ab38ec3a11fabb5515ed9bc3ac1a8e35a438d68bf7ff82f6b843
$ ▌
```
Use `with_native_path` for Windows
Ideally, each platform should use their own native path type internally. This will, for example, allow passing a UTF-16 string directly to `std::fs::File::open` and therefore avoid the need for allocating a new null-terminated wide string. However, doing that for every function and platform all at once makes for a large PR that is way too prone to breaking. So this just does some of the Windows parts.
As with the previous Unix PR (#138832) this is intended to be merely a refactoring so I've avoided anything that may require more substantial changes.
Fix profiler_builtins build script to handle full path to profiler lib
LLVM_PROFILER_RT_LIB may be set to an absolute path (e.g., in Fedora builds), but `-l` expects a library name, not a path. After #138273, this caused builds to fail with a "could not find native static library" error.
This patch updates the build script to split the path into directory and filename, using `cargo::rustc-link-search` for the directory and `cargo::rustc-link-lib=+verbatim` for the file. This allows profiler_builtins to correctly link the static library even when an absolute path is provided.
compiletest: Make `SUGGESTION` annotations viral
If one of them is expected in a test file, then others should be annotated as well, in the same way as with `HELP`s and `NOTE`s.
This doesn't require much of an additional annotation burden, but simplifies the rules.
r? ```@jieyouxu```
update ```miniz_oxide``` to 0.8.8
I would normally let the auto actions handle this but it turns out 0.8.7 can trigger a panic when debug assertions are enabled in a few cases so I feel it's important it gets sorted more quickly. (and I would ideally like to yank that version but was worried that could cause some issues had been pulled in as a dependency by this repo already before I discovered the problem)
As it can only happen when debug assertions are enabled (the overflow results in the intended result so it doesn't cause any issue in release mode) and using the wrapping buffer mode when decompressing it is very unlikely to cause any issues here but I would like to get it sorted just to be safe. ```miniz_oxide``` is used in the standard library (and some tools) via ```backtrace-rs ``` which doesn't use a wrapping buffer, and thus won't trigger this condition. There does however seem like there are some tools that do dependency on ```flate2``` which does use ```miniz_oxide``` decompression using a a wrapping buffer and could in theory trigger it if they are run when compiled with debug assertions enabled.
It's kinda unclear what version what tool uses though as several of them specify older versions of flate2 which depended on ```miniz_oxide``` 0.7.x in cargo.toml, and ```miniz_oxide```, and not all have a cargo.lock and due to an older version of ```backtrace``` being in the root Cargo.lock which still depended on ```miniz_oxide``` 0.7.4, so that version is also pulled in alongside the newer version.
libtest: Pass the test's panic payload as Option instead of Result
Passing a `Result<(), &dyn Any>` to `calc_result` requires awkward code at both call sites to build a fake result, for no real benefit. It's much easier to just pass the payload as `Option<&dyn Any>`.
No functional change.
std: Fix build for NuttX targets
Fix std build for all NuttX targets. It is the single largest set of failures on <https://does-it-build.noratrieb.dev/>. Although, ESP-IDF also requires these same gates, there are other issues for those targets.
This can verified be running `x check library/std --target=` for all NuttX targets.
cc ``@no1wudi``
Use the chaining methods on PartialOrd for slices too
#138135 added these doc-hidden trait methods to improve the tuple codegen. This PR adds more implementations and callers so that the codegen for slice (and array) comparisons also improves.
Rollup of 6 pull requests
Successful merges:
- #139107 (std: make `cmath` functions safe)
- #139607 (Add regression test for #127424)
- #139691 (Document that `opt-dist` requires metrics to be enabled)
- #139707 (Fix comment in bootstrap)
- #139708 (Fix name of field in doc comment)
- #139709 (bootstrap: fix typo in doc string)
r? `@ghost`
`@rustbot` modify labels: rollup
Add regression test for #127424
Fixes: https://github.com/rust-lang/rust/issues/127424
This ICE no longer reproduces, so it appears to have already been fixed.
This PR adds a regression test to ensure the issue doesn’t come back in the future.
Please let me know if there's anything I should improve or revise!
std: make `cmath` functions safe
The floating point intrinsics are more difficult, I'll probably wait until #119899 has merged before making them safe as well.
Polymorphize `array::IntoIter`'s iterator impl
Today we emit all the iterator methods for every different array width. That's wasteful since the actual array length never even comes into it -- the indices used are from the separate `alive: IndexRange` field, not even the `N` const param.
This PR switches things so that an `array::IntoIter<T, N>` stores a `PolymorphicIter<[MaybeUninit<T>; N]>`, which we *unsize* to `PolymorphicIter<[MaybeUninit<T>]>` and call methods on that non-`Sized` type for all the iterator methods.
That also necessarily makes the layout consistent between the different lengths of arrays, because of the unsizing. Compare that to today <https://rust.godbolt.org/z/Prb4xMPrb>, where different widths can't even be deduped because the offset to the indices is different for different array widths.
Use LTO to optimize Rust tools (cargo, miri, rustfmt, clippy, Rust Analyzer)
Trying if LTO/PGO can help RA's performance, and by how much. As `@Noratrieb` suggested, we could actually LTO optimize all the important tools.
CC `@Veykril` I realized that we don't even do LTO for Rust Analyzer, that could be a very low hanging fruit to improve its performance 😅
try-job: dist-x86_64-linux
Prepend temp files with per-invocation random string to avoid temp filename conflicts
https://github.com/rust-lang/rust/issues/139407 uncovered a very subtle unsoundness with incremental codegen, failing compilation sessions (due to assembler errors), and the "prefer hard linking over copying files" strategy we use in the compiler for file management.
Specifically, imagine we're building a single file 3 times, all with `-Csave-temps -Cincremental=...`. Let's call the object file we're building for the codegen unit for `main` "`XXX.o`" just for clarity since it's probably some gigantic hash name:
```
#[inline(never)]
#[cfg(any(rpass1, rpass3))]
fn a() -> i32 {
0
}
#[cfg(any(cfail2))]
fn a() -> i32 {
1
}
fn main() {
evil::evil();
assert_eq!(a(), 0);
}
mod evil {
#[cfg(any(rpass1, rpass3))]
pub fn evil() {
unsafe {
std::arch::asm!("/* */");
}
}
#[cfg(any(cfail2))]
pub fn evil() {
unsafe {
std::arch::asm!("missing");
}
}
}
```
Session 1 (`rpass1`):
* Type-check, borrow-check, etc.
* Serialize the dep graph to the incremental working directory `.../s-...-working/`.
* Codegen object file to a temp file `XXX.rcgu.o` which is spit out in the cwd.
* Hard-link[^1] `XXX.rcgu.o` to the incremental working directory `.../s-...-working/XXX.o`.
* Save-temps option means we don't delete `XXX.rgcu.o`.
* Link the binary and stuff.
* Finalize[^2] the working incremental session by renaming `.../s-...-working` to ` s-...-asjkdhsjakd` (some other finalized incr comp session dir name).
Session 2 (`cfail2`):
* Load artifacts from the previous *finalized* incremental session, namely the dep graph.
* Type-check, borrow-check, etc. since the file has changed, so most dep graph nodes are red.
* Serialize the dep graph to the incremental working directory `.../s-...-working/`.
* Codegen object file to a temp file `XXX.rcgu.o`. **HERE IS THE PROBLEM**: The hard-link is still set up to point to the inode from `XXX.o` from the first session, so this also modifies the `XXX.o` in the previous finalized session directory.
* Codegen emits an error b/c `missing` is not an instruction, so we abort before finalizing the incremental session. Specifically, this means that the *previous* session is the last finalized session.
Session 3 (`rpass3`):
* Load artifacts from the previous *finalized* incremental session, namely the dep graph. NOTE that this is from session 1.
* All the dep graph nodes are green since we are basically replaying session 1.
* codegen object file `XXX.o`, which is detected as *reused* from session 1 since dep nodes were green. That means we **reuse** `XXX.o` which had been dirtied from session 2.
* Link the binary and stuff.
This results in a binary which reuses some of the build artifacts from session 2, but thinks it's from session 1.
At this point, I hope it's clear to see that the incremental results from session 1 were dirtied from session 2, but we reuse them as if session 1 was the previous (finalized) incremental session we ran. This is at best really buggy, and at worst **unsound**.
This isn't limited to `-C save-temps`, since there are other combinations of flags that may keep around temporary files (hard linked) in the working directory (like `-C debuginfo=1 -C split-debuginfo=unpacked` on darwin, for example).
---
This PR implements a fix which is to prepend temp filenames with a random string that is generated per invocation of rustc. This string is not *deterministic*, but temporary files are transient anyways, so I don't believe this is a problem.
That means that temp files are now something like... `{crate-name}.{cgu}.{invocation_temp}.rcgu.o`, where `{invocation_temp}` is the new temporary string we generate per invocation of rustc.
Fixes https://github.com/rust-lang/rust/issues/139407
[^1]: 175dcc7773/compiler/rustc_fs_util/src/lib.rs (L60)
[^2]: 175dcc7773/compiler/rustc_incremental/src/persist/fs.rs (L1-L40)
1. added two new parts: Bootstrapping and Supporting Infrastructure;
2. touched up names of pre-existing parts, to match actual names in sidebar;
3. syntactic nits (start description of Analysis with a capital letter); and
4. make numbered list use only 1.
Co-authored-by: Tshepang Mbambo <tshepang@gmail.com>
Fix breakage when running compiletest with `--test-args=--edition=2015`
Compiletest has an `--edition` flag to change the default edition tests are run with. Unfortunately no test suite successfully executes when that flag is passed. If the edition is set to something greater than 2015 the breakage is expected, since the test suite currently supports only edition 2015 (Ferrous Systems will open an MCP about fixing that soonish). Surprisingly, the test suite is also broken if `--edition=2015` is passed to compiletest. This PR focuses on fixing the latter.
This PR fixes the two categories of failures happening when `--edition=2015` is passed:
* Some edition-specific tests set their edition through `//@ compile-flags` instead of `//@ edition`. Compiletest doesn't parse the compile flags, so it would see no `//@ edition` and add another `--edition` flag, leading to a rustc error.
* Compiletest would add the edition after `//@ compile-flags`, while some tests depend on flags passed to `//@ compile-flags` being the last flags in the rustc invocation.
Note that for the first category, I opted to manually go and replace all `//@ compile-flags` setting an edition with an explicit `//@ edition`. We could've changed compiletest to instead check whether an edition was set in `//@ compile-flags`, but I thought it was better to enforce a consistent way to set the edition in tests.
I also added the edition to the stamp, so that changing `--edition` results in tests being re-executed.
r? `@jieyouxu`
Improve `AssocItem::descr`.
The commit adds "associated" to the description of associated types and associated consts, to match the description of associated functions. This increases error message precision and consistency with `AssocKind::fmt`.
The commit also notes an imperfection in `AssocKind::fmt`; fixing this imperfection is possible but beyond the scope of this PR.
r? `@estebank`
Chris Denton
bors
Urgau
Tshepang Mbambo
许杰友 Jieyou Xu (Joe)
Oli Scherer
The Miri Cronjob Bot
Freya Arbjerg
Jakub Beránek
Stan Manilov
Stuart Cook