debug-fmt-detail option
I'd like to propose a new option that makes `#[derive(Debug)]` generate no-op implementations that don't print anything, and makes `{:?}` in format strings a no-op.
There are a couple of motivations for this:
1. A more thorough stripping of debug symbols. Binaries stripped of debug symbols still retain some of them through `Debug` implementations. It's hard to avoid that without compiler's help, because debug formatting can be used in many places, including dependencies, and their loggers, asserts, panics, etc.
* In my testing it gives about 2% binary size reduction on top of all other binary-minimizing best practices (including `panic_immediate_abort`). There are targets like Web WASM or embedded where users pay attention to binary sizes.
* Users distributing closed-source binaries may not want to "leak" any symbol names as a matter of principle.
2. Adds ability to test whether code depends on specifics of the `Debug` format implementation in unwise ways (e.g. trying to get data unavailable via public interface, or using it as a serialization format). Because current Rust's debug implementation doesn't change, there's a risk of it becoming a fragile de-facto API that [won't be possible to change in the future](https://www.hyrumslaw.com/). An option that "breaks" it can act as a [grease](https://www.rfc-editor.org/rfc/rfc8701.html).
This implementation is a `-Z fmt-debug=opt` flag that takes:
* `full` — the default, current state.
* `none` — makes derived `Debug` and `{:?}` no-ops. Explicit `impl Debug for T` implementations are left unharmed, but `{:?}` format won't use them, so they may get dead-code eliminated if they aren't invoked directly.
* `shallow` — makes derived `Debug` print only the type's name, without recursing into fields. Fieldless enums print their variant names. `{:?}` works.
The `shallow` option is a compromise between minimizing the `Debug` code, and compatibility. There are popular proc-macro crates that use `Debug::fmt` as a way to convert enum values into their Rust source code.
There's a corresponding `cfg` flag: `#[cfg(fmt_debug = "none")]` that can be used in user code to react to this setting to minimize custom `Debug` implementations or remove unnecessary formatting helper functions.
Fix path to run clippy on rustdoc
Took me a while to find out that the path clippy expected was `src/tools/rustdoc` and not `src/librustdoc`. I think it makes more sense this way as most commands rely on source paths.
r? ```@Kobzol```
Update books
## rust-lang/book
4 commits in 04bc1396bb857f35b5dda1d773c9571e1f253304..e7d217be2a75ef1753f0988d6ccaba4d7e376259
2024-08-14 01:19:47 UTC to 2024-08-13 16:51:00 UTC
- Backport/forward port ch12 (rust-lang/book#4008)
- Found some more things to fix in ch7; I forgot to update the snapshot (rust-lang/book#4007)
- Remove redundant sentence. Send to nostarch (rust-lang/book#4006)
- Fix: typo (rust-lang/book#4003)
## rust-lang/edition-guide
5 commits in aeeb287d41a0332c210da122bea8e0e91844ab3e..eeba2cb9c37ab74118a4fb5e5233f7397e4a91f8
2024-08-19 23:28:06 UTC to 2024-08-15 15:12:33 UTC
- 2024: Add rustdoc combined doctests (rust-lang/edition-guide#320)
- Update for unsafe attributes stabilization (rust-lang/edition-guide#319)
- 2024: Add macro-fragment-specifiers. (rust-lang/edition-guide#312)
- Fix deprecated_safe_2024 link (rust-lang/edition-guide#317)
- Add 2024 unsafe functions (rust-lang/edition-guide#304)
## rust-embedded/book
1 commits in 019f3928d8b939ec71b63722dcc2e46330156441..ff5d61d56f11e1986bfa9652c6aff7731576c37d
2024-08-20 07:26:19 UTC to 2024-08-20 07:26:19 UTC
- Use aligned address to demonstrate HardFault (rust-embedded/book#374)
## rust-lang/nomicon
1 commits in 6ecf95c5f2bfa0e6314dfe282bf775fd1405f7e9..14649f15d232d509478206ee9ed5105641aa60d0
2024-08-14 14:49:09 UTC to 2024-08-14 14:49:09 UTC
- CI: Switch to merge queue (rust-lang/nomicon#459)
## rust-lang/reference
14 commits in 62cd0df95061ba0ac886333f5cd7f3012f149da1..0668397076da350c404dadcf07b6cbc433ad3743
2024-08-11 21:06:12 +0000 to 2024-08-27 21:47:20 +0000
- Update enum.md (rust-lang/reference#1354)
- Be consistent about how "Edition differences" is capitalized (rust-lang/reference#1586)
- Sync denied lints with upstream (rust-lang/reference#1589)
- const_eval: update for const-fn float stabilization (rust-lang/reference#1566)
- Add spec identifier syntax to destructors.md (rust-lang/reference#1571)
- Say that `pub(in path)` can't depend on `use` statements (rust-lang/reference#1559)
- bytes inside implicitly const-promoted expressions are immutable (rust-lang/reference#1554)
- Tweak `repr(transparent)` to mention requiring *at most* one non-1-ZST (rust-lang/reference#1568)
- operator expressions: add &raw (rust-lang/reference#1567)
- Rewrite the automatic std link translation, and switch to automatic links (rust-lang/reference#1578)
- Add some basic docs for unsafe attrs (rust-lang/reference#1539)
- don't capitalize Undefined Behavior (rust-lang/reference#1575)
- add the `const` operand to docs for inline assembly (rust-lang/reference#1556)
- Typo: 'a' to 'an' in type-coercions.md (rust-lang/reference#1572)
## rust-lang/rust-by-example
1 commits in 8f94061936e492159f4f6c09c0f917a7521893ff..859786c5bc99301bbc22fc631a5c2b341860da08
2024-08-26 10:30:48 UTC to 2024-08-26 10:30:48 UTC
- Update primitives.md with examples (rust-lang/rust-by-example#1878)
## rust-lang/rustc-dev-guide
7 commits in 43d83780db545a1ed6d45773312fc578987e3968..fa928a6d19e1666d8d811dfe3fd35cdad3b4e459
2024-08-26 14:46:50 UTC to 2024-08-12 21:07:49 UTC
- Fix x.py reference (rust-lang/rustc-dev-guide#2049)
- Update `stabilization_guide.md` (rust-lang/rustc-dev-guide#2034)
- Explain the internal `#[rustc_*]` TEST attributes used for debugging and inside tests (rust-lang/rustc-dev-guide#2046)
- missing char (rust-lang/rustc-dev-guide#2047)
- Replace direct http links to rustc-dev-guide.rust-lang.org (rust-lang/rustc-dev-guide#2044)
- Update index.html, 39. The MIR: fix typo (rust-lang/rustc-dev-guide#2043)
- Update LLVM docs (rust-lang/rustc-dev-guide#2039)
Implement a first version of RFC 3525: struct target features
This PR is an attempt at implementing https://github.com/rust-lang/rfcs/pull/3525, behind a feature gate `struct_target_features`.
There's obviously a few tasks that ought to be done before this is merged; in no particular order:
- add proper error messages
- add tests
- create a tracking issue for the RFC
- properly serialize/deserialize the new target_features field in `rmeta` (assuming I even understood that correctly :-))
That said, as I am definitely not a `rustc` expert, I'd like to get some early feedback on the overall approach before fixing those things (and perhaps some pointers for `rmeta`...), hence this early PR :-)
Here's an example piece of code that I have been using for testing - with the new code, the calls to intrinsics get correctly inlined:
```rust
#![feature(struct_target_features)]
use std::arch::x86_64::*;
/*
// fails to compile
#[target_feature(enable = "avx")]
struct Invalid(u32);
*/
#[target_feature(enable = "avx")]
struct Avx {}
#[target_feature(enable = "sse")]
struct Sse();
/*
// fails to compile
extern "C" fn bad_fun(_: Avx) {}
*/
/*
// fails to compile
#[inline(always)]
fn inline_fun(_: Avx) {}
*/
trait Simd {
fn do_something(&self);
}
impl Simd for Avx {
fn do_something(&self) {
unsafe {
println!("{:?}", _mm256_setzero_ps());
}
}
}
impl Simd for Sse {
fn do_something(&self) {
unsafe {
println!("{:?}", _mm_setzero_ps());
}
}
}
struct WithAvx {
#[allow(dead_code)]
avx: Avx,
}
impl Simd for WithAvx {
fn do_something(&self) {
unsafe {
println!("{:?}", _mm256_setzero_ps());
}
}
}
#[inline(never)]
fn dosomething<S: Simd>(simd: &S) {
simd.do_something();
}
fn main() {
/*
// fails to compile
Avx {};
*/
if is_x86_feature_detected!("avx") {
let avx = unsafe { Avx {} };
dosomething(&avx);
dosomething(&WithAvx { avx });
}
if is_x86_feature_detected!("sse") {
dosomething(&unsafe { Sse {} })
}
}
```
Tracking:
- https://github.com/rust-lang/rust/issues/129107
interpret: do not make const-eval query result depend on tcx.sess
The check against calling functions with missing target features uses `tcx.sess` to determine which target features are available. However, this can differ between different crates in a crate graph, so the same const-eval query can come to different conclusions about whether a constant evaluates successfully or not -- which is bad, we should consistently get the same result everywhere.
const-eval: do not make UbChecks behavior depend on current crate's flags
Fixes https://github.com/rust-lang/rust/issues/129552
Let's see if we can get away with just always enabling these checks.
Make Tree Borrows Provenance GC compact the tree
Follow-up on #3833 and #3835. In these PRs, the TB GC was fixed to no longer cause a stack overflow. One test that motivated it was the test `fill::horizontal_line` in [`tiny-skia`](https://github.com/RazrFalcon/tiny-skia). But not causing stack overflows was not a large improvents, since it did not fix the fundamental issue: The tree was too large. The test now ran, but it required gigabytes of memory and hours of time (only for it to be OOM-killed 🤬), whereas it finishes within 24 seconds in Stacked Borrows. With this merged, it finishes in about 40 seconds under TB.
The problem in that test was that it used [`slice::chunked`](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks) to iterate a slice in chunks. That iterator is written to reborrow at each call to `next`, which creates a linear tree with a bunch of intermediary nodes, which also fragments the `RangeMap` for that allocation.
The solution is to now compact the tree, so that these interior nodes are removed. Care is taken to not remove nodes that are protected, or that otherwise restrict their children.
I am currently only 99% sure that this is sound, and I do also think that this could compact even more. So `@Vanille-N` please also have a look at whether I got the compacting logic right.
For a more visual comparison, [here is a gist](https://gist.github.com/JoJoDeveloping/ae4a7f7c29335a4c233ef42d2f267b01) of what the tree looks like at one point during that test, with and without compacting.
This new GC requires a different iteration order during accesses (since the current one can make the error messages non-deterministic), so it is rebased on top of #3843 and requires that PR to be merged first.
Stop storing a special inner body for the coroutine by-move body for async closures
...and instead, just synthesize an item which is treated mostly normally by the MIR pipeline.
This PR does a few things:
* We synthesize a new `DefId` for the by-move body of a closure, which has its `mir_built` fed with the output of the `ByMoveBody` MIR transformation, and some other relevant queries.
* This has the `DefKind::ByMoveBody`, which we use to distinguish it from "real" bodies (that come from HIR) which need to be borrowck'd. Introduce `TyCtxt::is_synthetic_mir` to skip over `mir_borrowck` which is called by `mir_promoted`; borrowck isn't really possible to make work ATM since it heavily relies being called on a body generated from HIR, and is redundant by the construction of the by-move-body.
* Remove the special `PassManager` hacks for handling the inner `by_move_body` stored within the coroutine's mir body. Instead, this body is fed like a regular MIR body, so it's goes through all of the `tcx.*_mir` stages normally (build -> promoted -> ...etc... -> optimized) ✨.
* Remove the `InstanceKind::ByMoveBody` shim, since now we have a "regular" def id, we can just use `InstanceKind::Item`. This also allows us to remove the corresponding hacks from codegen, such as in `fn_sig_for_fn_abi` ✨.
Notable remarks:
* ~~I know it's kind of weird to be using `DefKind::Closure` here, since it's not a distinct closure but just a new MIR body. I don't believe it really matters, but I could also use a different `DefKind`... maybe one that we could use for synthetic MIR bodies in general?~~ edit: We're doing this now.
Support blocking for epoll
This PR enabled epoll to have blocking operation.
The changes introduced by this PR are:
- Refactored part of the logic in ``epoll_wait`` to ``blocking_epoll_callback``
- Added a new field ``thread_ids`` in ``Epoll`` for blocked thread ids
- Added a new ``BlockReason::Epoll``
Follow-up on #3833 and #3835. In these PRs, the TB GC was fixed to no
longer cause a stack overflow. One test that motivated it was the test
`fill::horizontal_line` in `tiny_skia`. But not causing stack overflows
was not a large improvents, since it did not fix the fundamental issue:
The tree was too large. The test now ran, but it required gigabytes of
memory and hours of time, whereas it finishes within seconds in Stacked
Borrows.
The problem in that test was that it used [`slice::chunked`](https://doc.rust-lang.org/std/primitive.slice.html#method.chunks) to iterate
a slice in chunks. That iterator is written to reborrow at each call to
`next`, which creates a linear tree with a bunch of intermediary nodes,
which also fragments the `RangeMap` for that allocation.
The solution is to now compact the tree, so that these interior nodes
are removed. Care is taken to not remove nodes that are protected, or
that otherwise restrict their children.
In preparation for #3837, the tree traversal needs to be made bottom-up,
because the current top-down tree traversal, coupled with that PR's
changes to the garbage collector, can introduce non-deterministic error
messages if the GC removes a parent tag of the accessed tag that would
have triggered the error first.
This is a breaking change for the diagnostics emitted by TB. The
implemented semantics stay the same.
Disable tree traversal optimization that is wrong due to lazy nodes.
See #3846 for more information.
For now, the optimization is disabled in a very "hotfix" way, while we think about potential fixes. Nonetheless, this fixes#3846
Add Trusty OS as tier 3 target
This PR adds support for the [Trusty secure operating system](https://source.android.com/docs/security/features/trusty) as a Tier 3 supported target. This upstreams [the patch that we have been using](https://cs.android.com/android/platform/superproject/+/master:external/rust/crates/libc/patches/trusty.patch;l=1;drc=122e586e93a534160230dc10ae3474cf31dd8f7f) internally. This also revives https://github.com/rust-lang/rust/pull/103895 which was closed due to inactivity, and is being resumed now that time allows.
And MCP has already been done for adding this platform: rust-lang/compiler-team/issues/568
# Target Tier Policy Acknowledgements
> A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
- Nicole LeGare (``@randomPoison)``
- Stephen Crane (``@rinon)``
- As a fallback trusty-dev-team@google.com can be contacted
> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
The two new Trusty targets, `aarch64-unknown-trusty` and `armv7-unknown-trusty` both follow the existing naming convention for similar targets.
> Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
👍
> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
There are no known legal issues or license incompatibilities.
> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
👍
> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
This PR only adds the targets for the platform. `std` support will be added once platform support is added to the libc crate, which depends on the language targets being added to rustc.
> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
👍
> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via ``@)`` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
👍
> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
👍
> Tier 3 targets must be able to produce assembly using at least one of rustc's supported backends from any host target. (Having support in a fork of the backend is not sufficient, it must be upstream.)
👍
miri weak memory emulation: put previous value into initial store buffer
Fixes https://github.com/rust-lang/miri/issues/2164 by doing a read before each atomic write so that we can initialize the store buffer. The read suppresses memory access hooks and UB exceptions, to avoid otherwise influencing the program behavior. If the read fails, we store that as `None` in the store buffer, so that when an atomic read races with the first atomic write to some memory and previously the memory was uninitialized, we can report UB due to reading uninit memory.
``@cbeuw`` this changes a bit the way we initialize the store buffers. Not sure if you still remember all this code, but if you could have a look to make sure this still makes sense, that would be great. :)
r? ``@saethlin``
More work on `zstd` compression
r? ``@Kobzol`` as we've discussed this.
This is a draft to show the current approach of supporting zstd in compiletest, and making the tests using it unconditional.
Knowing whether llvm/lld was built with `LLVM_ENABLE_ZSTD` is quite hard, so there are two strategies. There are details in the code, and we can discuss this approach. Until we know the config used to build CI artifacts, it seems our options are somewhat limited in any case.
zlib compression seems always enabled, so we only check this in its dedicated test, allowing the test to ignore errors due to zstd not being supported.
The zstd test is made unconditional in what it tests, by relying on `needs-llvm-zstd` to be ignored when `llvm.libzstd` isn't enabled in `config.toml`.
try-job: x86_64-gnu
try-job: x86_64-msvc
try-job: x86_64-gnu-distcheck
