Add future-incompat lint for `doc(primitive)`
## What is `doc(primitive)`?
`doc(primitive)` is an attribute recognized by rustdoc which adds documentation for the built-in primitive types, such as `usize` and `()`. It has been stable since Rust 1.0.
## Why change anything?
`doc(primitive)` is useless for anyone outside the standard library. Since rustdoc provides no way to combine the documentation on two different primitive items, you can only replace the docs, and since the standard library already provides extensive documentation there is no reason to do so.
While fixing rustdoc's handling of primitive items (https://github.com/rust-lang/rust/pull/87073) I discovered that even rustdoc's existing handling of primitive items was broken if you had more than two crates using it (it would pick randomly between them). That meant both:
- Keeping rustdoc's existing treatment was nigh-impossible, because it was random.
- doc(primitive) was even more useless than it would otherwise be.
The only use-case for this outside the standard library is for no-std libraries which want to link to primitives (https://github.com/rust-lang/rust/issues/73423) which is being fixed in https://github.com/rust-lang/rust/pull/87073.
https://github.com/rust-lang/rust/pull/87073 makes various breaking changes to `doc(primitive)` (breaking in the sense that they change the semantics, not in that they cause code to fail to compile). It's not possible to avoid these and still fix rustdoc's issues.
## What can we do about it?
As shown by the crater run (https://github.com/rust-lang/rust/pull/87050#issuecomment-886166706), no one is actually using doc(primitive), there wasn't a single true regression in the whole run. We can either:
1. Feature gate it completely, breaking anyone who crater missed. They can easily fix the breakage just by removing the attribute.
2. add it to the `INVALID_DOC_ATTRIBUTES` future-incompat lint, and at the same time make it a no-op unless you add a feature gate. That would mean rustdoc has to look at the features of dependent crates, because it needs to know where primitives are defined in order to link to them.
3. add it to `INVALID_DOC_ATTRIBUTES`, but still use it to determine where primitives come from
4. do nothing; the behavior will silently change in https://github.com/rust-lang/rust/pull/87073.
My preference is for 2, but I would also be happy with 1 or 3. I don't think we should silently change the behavior.
This PR currently implements 3.
Uplift the invalid_atomic_ordering lint from clippy to rustc
This is mostly just a rebase of https://github.com/rust-lang/rust/pull/79654; I've copy/pasted the text from that PR below.
r? `@lcnr` since you reviewed the last one, but feel free to reassign.
---
This is an implementation of https://github.com/rust-lang/compiler-team/issues/390.
As mentioned, in general this turns an unconditional runtime panic into a (compile time) lint failure. It has no false positives, and the only false negatives I'm aware of are if `Ordering` isn't specified directly and is comes from an argument/constant/whatever.
As a result of it having no false positives, and the alternative always being strictly wrong, it's on as deny by default. This seems right.
In the [zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Uplift.20the.20.60invalid_atomic_ordering.60.20lint.20from.20clippy/near/218483957) `@joshtriplett` suggested that lang team should FCP this before landing it. Perhaps libs team cares too?
---
Some notes on the code for reviewers / others below
## Changes from clippy
The code is changed from [the implementation in clippy](68cf94f6a6/clippy_lints/src/atomic_ordering.rs) in the following ways:
1. Uses `Symbols` and `rustc_diagnostic_item`s instead of string literals.
- It's possible I should have just invoked Symbol::intern for some of these instead? Seems better to use symbol, but it did require adding several.
2. The functions are moved to static methods inside the lint struct, as a way to namespace them.
- There's a lot of other code in that file — which I picked as the location for this lint because `@jyn514` told me that seemed reasonable.
3. Supports unstable AtomicU128/AtomicI128.
- I did this because it was almost easier to support them than not — not supporting them would have (ideally) required finding a way not to give them a `rustc_diagnostic_item`, which would have complicated an already big macro.
- These don't have tests since I wasn't sure if/how I should make tests conditional on whether or not the target has the atomic... This is to a certain extent an issue of 64bit atomics too, but 128-bit atomics are much less common. Regardless, the existing tests should be *more* than thorough enough here.
4. Minor changes like:
- grammar tweaks ("loads cannot have `Release` **and** `AcqRel` ordering" => "loads cannot have `Release` **or** `AcqRel` ordering")
- function renames (`match_ordering_def_path` => `matches_ordering_def_path`),
- avoiding clippy-specific helper methods that don't exist in rustc_lint and didn't seem worth adding for this case (for example `cx.struct_span_lint` vs clippy's `span_lint_and_help` helper).
## Potential issues
(This is just about the code in this PR, not conceptual issues with the lint or anything)
1. I'm not sure if I should have used a diagnostic item for `Ordering` and its variants (I couldn't figure out how really, so if I should do this some pointers would be appreciated).
- It seems possible that failing to do this might possibly mean there are more cases this lint would miss, but I don't really know how `match_def_path` works and if it has any pitfalls like that, so maybe not.
2. I *think* I deprecated the lint in clippy (CC `@flip1995` who asked to be notified about clippy changes in the future in [this comment](https://github.com/rust-lang/rust/pull/75671#issuecomment-718731659)) but I'm not sure if I need to do anything else there.
- I'm kind of hoping CI will catch if I missed anything, since `x.py test src/tools/clippy` fails with a lot of errors with and without my changes (and is probably a nonsense command regardless). Running `cargo test` from src/tools/clippy also fails with unrelated errors that seem like refactorings that didnt update clippy? So, honestly no clue.
3. I wasn't sure if the description/example I gave good. Hopefully it is. The example is less thorough than the one from clippy here: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_atomic_ordering. Let me know if/how I should change it if it needs changing.
4. It pulls in the `if_chain` crate. This crate was already used in clippy, and seems like it's used elsewhere in rustc, but I'm willing to rewrite it to not use this if needed (I'd prefer not to, all things being equal).
- Deprecate clippy::invalid_atomic_ordering
- Use rustc_diagnostic_item for the orderings in the invalid_atomic_ordering lint
- Reduce code duplication
- Give up on making enum variants diagnostic items and just look for
`Ordering` instead
I ran into tons of trouble with this because apparently the change to
store HIR attrs in a side table also gave the DefIds of the
constructor instead of the variant itself. So I had to change
`matches_ordering` to also check the grandparent of the defid as well.
- Rename `atomic_ordering_x` symbols to just the name of the variant
- Fix typos in checks - there were a few places that said "may not be
Release" in the diagnostic but actually checked for SeqCst in the lint.
- Make constant items const
- Use fewer diagnostic items
- Only look at arguments after making sure the method matches
This prevents an ICE when there aren't enough arguments.
- Ignore trait methods
- Only check Ctors instead of going through `qpath_res`
The functions take values, so this couldn't ever be anything else.
- Add if_chain to allowed dependencies
- Fix grammar
- Remove unnecessary allow
BTree: merge the complication introduced by #81486 and #86031
Also:
- Deallocate the last few tree nodes as soon as an `into_iter` iterator steps beyond the end, instead of waiting around for the drop of the iterator (just to share more code).
- Symmetric code for backward iteration.
- Mark unsafe the methods on dying handles, modelling dying handles after raw pointers: it's the caller's responsibility to use them safely.
r? `@Mark-Simulacrum`
Deprecate llvm_asm!
We would like to remove `llvm_asm!` from the compiler once `asm!` is stabilized. This PR deprecates `llvm_asm!` to encourage any remaining users to migrate to `asm!` (or if `asm!` is not supported for their target, to add this support to rustc).
The only remaining user of `llvm_asm!` in the standard library was `black_box`, which has been rewritten to use volatile operations when `asm!` is not available on the current target.
cc `@rust-lang/wg-inline-asm`
cc `@RalfJung` for the changes to `black_box` which might affect Miri.
r? `@nagisa`
Test and fix `size_hint` for slice’s [r]split* iterators
Adds extensive test (of `size_hint`) for all the _[r]split*_ iterators.
Fixes `size_hint` upper bound for _split_inclusive*_ iterators which was one higher than necessary for non-empty slices.
Fixes `size_hint` lower bound for _[r]splitn*_ iterators when _n == 0_, which was one too high.
**Lower bound being one too high was a logic error, violating the correctness condition of `size_hint`.**
_Edit:_ I’ve opened an issue for that bug, so this PR fixes#87978
Add support for clobber_abi to asm!
This PR adds the `clobber_abi` feature that was proposed in #81092.
Fixes#81092
cc `@rust-lang/wg-inline-asm`
r? `@nagisa`
Lint against named asm labels
This adds a deny-by-default lint to prevent the use of named labels in inline `asm!`. Without a solution to #81088 about whether the compiler should rewrite named labels or a special syntax for labels, a lint against them should prevent users from writing assembly that could break for internal compiler reasons, such as inlining or anything else that could change the number of actual inline assembly blocks emitted.
This does **not** resolve the issue with rewriting labels, that still needs a decision if the compiler should do any more work to try to make them work.
Specialize `Vec::clone_from` for `Copy` types
This should improve performance and reduce code size.
This also improves `clone_from` for `String`, `OsString` and `PathBuf`.
Try filtering out non-const impls when we expect const impls
**TL;DR**: Associated types on const impls are now bounded; we now disallow calling a const function with bounds when the specified type param only has a non-const impl.
r? `@oli-obk`
Move some UI tests to more suitable subdirs
The classifui result: https://gist.github.com/JohnTitor/c9e00840990b5e4a8fc562ec3571e427/e06c42226c6038da91e403c33b9947843420cf44
Some notes:
- backtrace-debuginfo.rs: previously I skipped this, I'm still not sure what the best dir is. Any ideas?
- estr-subtyping.rs: Seems a quite old test so removed, shouldn't?
- deref-suggestion.rs: moved to inference as `suggestions` is not an ideal dir.
- issue-43023.rs: a bit misclassified, moved to `derives`
cc #73494
r? `@petrochenkov`
Name the captured upvars for closures/generators in debuginfo
Previously, debuggers print closures as something like
```
y::main::closure-0 (0x7fffffffdd34)
```
The pointer actually references to an upvar. It is not very obvious, especially for beginners.
It's because upvars don't have names before, as they are packed into a tuple. This PR names the upvars, so we can expect to see something like
```
y::main::closure-0 {_captured_ref__b: 0x[...]}
```
r? `@tmandry`
Discussed at https://github.com/rust-lang/rust/pull/84752#issuecomment-831639489 .
Associated functions that contain extern indicator or have `#[rustc_std_internal_symbol]` are reachable
Previously these fails to link with ``undefined reference to `foo'``:
<details>
<summary>Example 1</summary>
```rs
struct AssocFn;
impl AssocFn {
#[no_mangle]
fn foo() {}
}
fn main() {
extern "Rust" {
fn foo();
}
unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=f1244afcdd26e2a28445f6e82ca46b50))
</details>
<details>
<summary>Example 2</summary>
```rs
#![crate_name = "lib"]
#![crate_type = "lib"]
struct AssocFn;
impl AssocFn {
#[no_mangle]
fn foo() {}
}
```
```rs
extern crate lib;
fn main() {
extern "Rust" {
fn foo();
}
unsafe { foo() }
}
```
</details>
But I believe they should link successfully, because this works:
<details>
```rs
#[no_mangle]
fn foo() {}
fn main() {
extern "Rust" {
fn foo();
}
unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=789b3f283ee6126f53939429103ed98d))
</details>
This PR fixes the problem, by adding associated functions that have "custom linkage" to `reachable_set`, just like normal functions.
I haven't tested whether #76211 and [Miri](https://github.com/rust-lang/miri/issues/1837) are fixed by this PR yet, but I'm submitting this anyway since this fixes the examples above.
I added a `run-pass` test that combines my two examples above, but I'm not sure if that's the right way to test this. Maybe I should add / modify an existing codegen test (`src/test/codegen/export-no-mangle.rs`?) instead?
Revert "Rollup merge of #87779 - Aaron1011:stmt-ast-id, r=petrochenkov"
Fixes#87877
This change interacts badly with `noop_flat_map_stmt`,
which synthesizes multiple statements with the same `NodeId`.
I'm working on a better fix that will still allow us to
remove this special case. For now, let's revert the change
to fix the ICE.
This reverts commit a4262cc984, reversing
changes made to 8ee962f88e.
Fix `command-create-pidfd` test inside unprivileged Docker containers
In `src/test/ui/command/command-create-pidfd.rs` (added #81825), the detection code to skip the test on unsupported platforms doesn't account for unprivileged Docker containers (CI uses privileged containers), which leads to a test failure as you can't call the `clone3` syscall in that environment. This PR enhances the detection code to also consider unprivileged containers.
Avoid ICE caused by suggestion
When suggesting dereferencing something that can be iterable in a `for`
loop, erase lifetimes and use a fresh `ty::ParamEnv` to avoid 'region
constraints already solved' panic.
Fix#87657, fix#87709, fix#87651.
