privacy: Refactor top-level visiting in `NamePrivacyVisitor`
Full hierarchical visiting (`nested_filter::All`) is not necessary, visiting all item-likes in isolation is enough.
Tracking current item is not necessary, passing any `HirId` with the same parent module to `adjust_ident_and_get_scope` is enough.
Follow up to https://github.com/rust-lang/rust/pull/120284.
Remove special-case handling of `vec.split_off(0)`
#76682 added special handling to `Vec::split_off` for the case where `at == 0`. Instead of copying the vector's contents into a freshly-allocated vector and returning it, the special-case code steals the old vector's allocation, and replaces it with a new (empty) buffer with the same capacity.
That eliminates the need to copy the existing elements, but comes at a surprising cost, as seen in #119913. The returned vector's capacity is no longer determined by the size of its contents (as would be expected for a freshly-allocated vector), and instead uses the full capacity of the old vector.
In cases where the capacity is large but the size is small, that results in a much larger capacity than would be expected from reading the documentation of `split_off`. This is especially bad when `split_off` is called in a loop (to recycle a buffer), and the returned vectors have a wide variety of lengths.
I believe it's better to remove the special-case code, and treat `at == 0` just like any other value:
- The current documentation states that `split_off` returns a “newly allocated vector”, which is not actually true in the current implementation when `at == 0`.
- If the value of `at` could be non-zero at runtime, then the caller has already agreed to the cost of a full memcpy of the taken elements in the general case. Avoiding that copy would be nice if it were close to free, but the different handling of capacity means that it is not.
- If the caller specifically wants to avoid copying in the case where `at == 0`, they can easily implement that behaviour themselves using `mem::replace`.
Fixes#119913.
Don't manually resolve async closures in `rustc_resolve`
There's a comment here that talks about doing this "[so] closure [args] are detected as upvars rather than normal closure arg usages", but we do upvar analysis on the HIR now:
cd6d8f2a04/compiler/rustc_passes/src/upvars.rs (L21-L29)
Removing this ad-hoc logic makes it so that `async |x: &str|` now introduces an implicit binder, like regular closures.
r? ```@oli-obk```
Builtin macros effectively have implicit #[collapse_debuginfo(yes)]
If collapse_debuginfo attribute for builtin macro is not specified explicitly, it will be effectively set to `#[collapse_debuginfo(yes)]`.
Split assembly tests for ELF and MachO
On ELF, the text section is opened with ".text", on MachO with ".section __TEXT,__text".
Previously, on ELF this test was actually matching a GNU note section, which is no longer emitted on Solaris starting with LLVM 18.
Fixes https://github.com/rust-lang/rust/issues/120105.
r? ```@davidtwco```
Specialize `Bytes` on `StdinLock<'_>`
I noticed recently, while profiling a little project, that I was spending a lot of time reading from stdin (even with locking). I was using the `.bytes()` iterator adaptor; I figured, since `StdinLock` is a `BufReader` internally, it would work just as fast. But this is not the case, as `Bytes` is only specialized for the raw `BufReader`, and not the `StdinLock`/`MutexGuard` wrapper. Performance improved significantly when I wrapped the lock in a new `BufReader`, but I was still a bit sore about the double buffer indirection.
This PR attempts to specialize it, by simply calling the already specialized implementation on `BufReader`.
Initial implementation of `str::from_raw_parts[_mut]`
ACP (accepted): rust-lang/libs-team#167
Tracking issue: #119206
Thanks to ``@Kixiron`` for previous work on this (#107207)
``@rustbot`` label +T-libs-api -T-libs
r? ``@thomcc``
Closes#107207.
Add the `min_exhaustive_patterns` feature gate
## Motivation
Pattern-matching on empty types is tricky around unsafe code. For that reason, current stable rust conservatively requires arms for empty types in all but the simplest case. It has long been the intention to allow omitting empty arms when it's safe to do so. The [`exhaustive_patterns`](https://github.com/rust-lang/rust/issues/51085) feature allows the omission of all empty arms, but hasn't been stabilized because that was deemed dangerous around unsafe code.
## Proposal
This feature aims to stabilize an uncontroversial subset of exhaustive_patterns. Namely: when `min_exhaustive_patterns` is enabled and the data we're matching on is guaranteed to be valid by rust's operational semantics, then we allow empty arms to be omitted. E.g.:
```rust
let x: Result<T, !> = foo();
match x { // ok
Ok(y) => ...,
}
let Ok(y) = x; // ok
```
If the place is not guaranteed to hold valid data (namely ptr dereferences, ref dereferences (conservatively) and union field accesses), then we keep stable behavior i.e. we (usually) require arms for the empty cases.
```rust
unsafe {
let ptr: *const Result<u32, !> = ...;
match *ptr {
Ok(x) => { ... }
Err(_) => { ... } // still required
}
}
let foo: Result<u32, &!> = ...;
match foo {
Ok(x) => { ... }
Err(&_) => { ... } // still required because of the dereference
}
unsafe {
let ptr: *const ! = ...;
match *ptr {} // already allowed on stable
}
```
Note that we conservatively consider that a valid reference can point to invalid data, hence we don't allow arms of type `&!` and similar cases to be omitted. This could eventually change depending on [opsem decisions](https://github.com/rust-lang/unsafe-code-guidelines/issues/413). Whenever opsem is undecided on a case, we conservatively keep today's stable behavior.
I proposed this behavior in the [`never_patterns`](https://github.com/rust-lang/rust/issues/118155) feature gate but it makes sense on its own and could be stabilized more quickly. The two proposals nicely complement each other.
## Unresolved Questions
Part of the question is whether this requires an RFC. I'd argue this doesn't need one since there is no design question beyond the intent to omit unreachable patterns, but I'm aware the problem can be framed in ways that require design (I'm thinking of the [original never patterns proposal](https://smallcultfollowing.com/babysteps/blog/2018/08/13/never-patterns-exhaustive-matching-and-uninhabited-types-oh-my/), which would frame this behavior as "auto-nevering" happening).
EDIT: I initially proposed a future-compatibility lint as part of this feature, I don't anymore.
Remove unused/unnecessary features
~~The bulk of the actual code changes here is replacing try blocks with equivalent closures. I'm not entirely sure that's a good idea since it may have perf impact, happy to revert if that's the case/the change is unwanted.~~
I also removed a lot of `recursion_limit = "256"` since everything seems to build fine without that and most don't have any comment justifying it.
remove StructuralEq trait
The documentation given for the trait is outdated: *all* function pointers implement `PartialEq` and `Eq` these days. So the `StructuralEq` trait doesn't really seem to have any reason to exist any more.
One side-effect of this PR is that we allow matching on some consts that do not implement `Eq`. However, we already allowed matching on floats and consts containing floats, so this is not new, it is just allowed in more cases now. IMO it makes no sense at all to allow float matching but also sometimes require an `Eq` instance. If we want to require `Eq` we should adjust https://github.com/rust-lang/rust/pull/115893 to check for `Eq`, and rule out float matching for good.
Fixes https://github.com/rust-lang/rust/issues/115881
Rollup of 8 pull requests
Successful merges:
- #118208 (Rewrite the BTreeMap cursor API using gaps)
- #120099 (linker: Refactor library linking methods in `trait Linker`)
- #120288 (Bump `askama` version)
- #120306 (Clean up after clone3 removal from pidfd code (docs and tests))
- #120316 (Don't call `walk_` functions directly if there is an equivalent `visit_` method)
- #120330 (Remove coroutine info when building coroutine drop body)
- #120332 (Remove unused struct)
- #120338 (Fix links to [strict|exposed] provenance sections of `[std|core]::ptr`)
r? `@ghost`
`@rustbot` modify labels: rollup
Remove coroutine info when building coroutine drop body
Coroutine drop shims are not themselves coroutines, so erase the "`coroutine`" field from the body so that helper fns like `yield_ty` and `coroutine_kind` properly return `None` for the drop shim.
Don't call `walk_` functions directly if there is an equivalent `visit_` method
I was working on https://github.com/rust-lang/rust/issues/77773 and realized in one of my experiments that the `visit_path` method was not always called whereas it should have. This fixes it.
r? ``@davidtwco``
Clean up after clone3 removal from pidfd code (docs and tests)
https://github.com/rust-lang/rust/pull/113939 removed clone3 from pidfd code. This patchset does necessary clean up: fixes docs and tests
linker: Refactor library linking methods in `trait Linker`
Linkers are not aware of Rust libraries, they look like regular static or dynamic libraries to them, so Rust-specific methods in `trait Linker` do not make much sense.
They can be either removed or renamed to something more suitable.
Commits after the second one are cleanups.
Consolidating rustc Dependencies
changelog: none
For dependencies in rustc where there are multiple versions used, this moves the older dependency to the newer dependency. These are the updates to clippy as mentioned here: https://github.com/rust-lang/rust/pull/120177
On ELF, the text section is opened with ".text", on MachO with
".section __TEXT,__text".
Previously, on ELF this test was actually matching a GNU note
section, which is no longer emitted on Solaris starting with
LLVM 18.
Fixes https://github.com/rust-lang/rust/issues/120105.
Rollup of 10 pull requests
Successful merges:
- #119305 (Add `AsyncFn` family of traits)
- #119389 (Provide more context on recursive `impl` evaluation overflow)
- #119895 (Remove `track_errors` entirely)
- #120230 (Assert that a single scope is passed to `for_scope`)
- #120278 (Remove --fatal-warnings on wasm targets)
- #120292 (coverage: Dismantle `Instrumentor` and flatten span refinement)
- #120315 (On E0308 involving `dyn Trait`, mention trait objects)
- #120317 (pattern_analysis: Let `ctor_sub_tys` return any Iterator they want)
- #120318 (pattern_analysis: Reuse most of the `DeconstructedPat` `Debug` impl)
- #120325 (rustc_data_structures: use either instead of itertools)
r? `@ghost`
`@rustbot` modify labels: rollup
rustc_data_structures: use either instead of itertools
`itertools::Either` is a re-export from `either`, so we might as well use the source.
This flattens the compiler build tree a little, but I don't really expect it to make much difference overall.
pattern_analysis: Reuse most of the `DeconstructedPat` `Debug` impl
The `DeconstructedPat: Debug` is best-effort because we'd need `tcx` to get things like field names etc. Since rust-analyzer has a similar constraint, this PR moves most the impl to be shared between the two. While I was at it I also fixed a nit in the `IntRange: Debug` impl.
r? `@compiler-errors`
pattern_analysis: Let `ctor_sub_tys` return any Iterator they want
I noticed that we always `.cloned()` and allocate the output of `TypeCx::ctor_sub_tys` now, so there was no need to force it to return a slice. `ExactSizeIterator` is not super important but saves some manual counting.
r? `@compiler-errors`
On E0308 involving `dyn Trait`, mention trait objects
When encountering a type mismatch error involving `dyn Trait`, mention the existence of boxed trait objects if the other type involved implements `Trait`.
Fix#102629.
coverage: Dismantle `Instrumentor` and flatten span refinement
This is a combination of two refactorings that are unrelated, but would otherwise have a merge conflict.
No functional changes, other than a small tweak to debug logging as part of rearranging some functions.
Ignoring whitespace is highly recommended, since most of the modified lines have just been reindented.
---
The first change is to dismantle `Instrumentor` into ordinary functions.
This is one of those cases where encapsulating several values into a struct ultimately hurts more than it helps. With everything stored as local variables in one main function, and passed explicitly into helper functions, it's easier to see what is used where, and make changes as necessary.
---
The second change is to flatten the functions for extracting/refining coverage spans.
Consolidating this code into flatter functions reduces the amount of pointer-chasing required to read and modify it.
Remove --fatal-warnings on wasm targets
These were added with good intentions, but a recent change in LLVM 18 emits a warning while examining .rmeta sections in .rlib files. Since this flag is a nice-to-have and users can update their LLVM linker independently of rustc's LLVM version, we can just omit the flag.
See [this comment on wasm targets' uses of `--fatal-warnings`](https://github.com/llvm/llvm-project/pull/78658#issuecomment-1906651390).
Remove `track_errors` entirely
follow up to https://github.com/rust-lang/rust/pull/119869
r? `@matthewjasper`
There are some diagnostic changes adding new diagnostics or not emitting some anymore. We can improve upon that in follow-up work imo.
