Link `std` statically in `rustc_driver`
This makes `rustc_driver` statically link to `std`. This is done by not passing `-C prefer-dynamic` when building `rustc_driver`. However building `rustc-main` won't work currently as it tries to dynamically link to both `rustc_driver` and `std` resulting in a crate graph with `std` duplicated. To fix that new command line option `-Z prefer_deps_of_dynamic` is added which prevents linking to a dylib if there's a static variant of it already statically linked into another dylib dependency.
The main motivation for this change is to enable `#[global_allocator]` to be used in `rustc_driver` allowing overriding the allocator used in rustc on all platforms.
---
Instead of adding `-Z prefer_deps_of_dynamic`, this PR is changed to crate opt-in to the linking change via the `rustc_private` feature instead, as that would be typically needed to link to `rustc_driver` anyway.
---
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: dist-x86_64-msvc
try-job: aarch64-gnu
Tidy up `dump-ice-to-disk` and make assertion failures dump ICE messages
For the future traveler: **if you did a `git blame` and found this PR that last modified `dump-ice-to-disk` because the test failed in a completely unrelated PR, then I'm afraid our ICE dump may have regressed or somehow behaves differently on `i686-mingw`.**
A bit of clean up to the `dump-ice-to-disk` test.
- Fixes/updates the top-level comment.
- Add a FIXME pointing to #128911 for flakiness.
- Instead of trying to manually cleanup `rustc-ice*.txt` dumps, run each test instance in a separate temp directory.
- Explicitly make `RUSTC_ICE` unavailable in one of the `-Zmetrics-dir` test case to not have interference from environment.
- Make assertion failures (on ICE dump line count mismatch) extremely verbose to help debug why this test is flakey in CI (#128911).
Contains a fix by `@saethlin` in #128909, should wait until that is merged then rebase on top.
try-job: aarch64-gnu
try-job: aarch64-apple
try-job: x86_64-msvc
try-job: i686-mingw
try-job: test-various
rm `import.used`
By the way, `import_used_map` will only be used during `build_reduced_graph` and `finalize`, so it can be split from `Resolver` in the future.
r? ``@petrochenkov``
Use more slice patterns inside the compiler
Nothing super noteworthy. Just replacing the common 'fragile' pattern of "length check followed by indexing or unwrap" with slice patterns for legibility and 'robustness'.
r? ghost
Promote aarch64-apple-darwin to Tier 1
This promotes aarch64-apple-darwin to Tier 1 status as per rust-lang/rfcs#3671 and tracking issue #73908. Not sure what else is necessary for this to impement the aforementioned RFC, however I figured I'd try. I did read in previous issues and PRs that the necessary infrastructure was already in place for the aarch64-apple-darwin target, and the RFC mentions the same. So this should be all thats necessary in order for the target to be promoted.
This is a recreation of my previous PR because I accidentally did an incorrect git rebase which caused unnecessary changes to various commit SHAs. So this PR is a recreation of my previous PR without said stumble. My bad.
Preliminary cleanup of `WitnessPat` hoisting/printing
Follow-up to #128430.
The eventual goal is to remove `print::Pat` entirely, but in the course of working towards that I made so many small improvements that it seems wise to let those be reviewed/merged on their own first.
Best reviewed commit-by-commit, most of which should be pretty simple and straightforward.
r? ``@Nadrieril``
core: optimise Debug impl for ascii::Char
Rather than writing character at a time, optimise Debug implementation
for core::ascii::Char such that it writes the entire representation
with a single write_str call.
With that, add tests for Display and Debug.
Issue: https://github.com/rust-lang/rust/issues/110998
Fix `ElaborateBoxDerefs` on debug varinfo
Slightly simplifies the `ElaborateBoxDerefs` pass to fix cases where it was applying the wrong projections to debug var infos containing places that deref boxes.
From what I can tell[^1], we don't actually have any tests (or code anywhere, really) that exercise `debug x => *(...: Box<T>)`, and it's very difficult to trigger this in surface Rust, so I wrote a custom MIR test.
What happens is that the pass was turning `*(SOME_PLACE: Box<T>)` into `*(*((((SOME_PLACE).0: Unique<T>).0: NonNull<T>).0: *const T))` in debug var infos. In particular, notice the *double deref*, which was wrong.
This is the root cause of #128554, so this PR fixes#128554 as well. The reason that async closures was affected is because of the way that we compute the [`ByMove` body](https://github.com/rust-lang/rust/blob/master/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs), which resulted in `*(...: Box<T>)` in debug var info. But this really has nothing to do with async closures.
[^1]: Validated by literally replacing the `if elem == PlaceElem::Deref && base_ty.is_box() { ... }` innards with a `panic!()`, which compiled all of stage2 without panicking.
[rustdoc] Stop showing impl items for negative impls
Fixes https://github.com/rust-lang/rust/issues/128799.
As discussed with `@fmease,` they have a broader patch in progress, so this (small) PR will at least allow for them to have a regression test. :)
r? `@fmease`
Differentiate between methods and associated functions in diagnostics
Accurately refer to assoc fn without receiver as assoc fn instead of methods. Add `AssocItem::descr` method to centralize where we call methods and associated functions.
run-make: explaing why fmt-write-bloat is ignore-windows
The trouble here is that libc doesn't exist on Windows. Well it kinda does but it isn't called that so we substitute a name that works. Ideally finding necessary libs for the platform would be done at a higher level but until then this should work.
try-job: x86_64-msvc
try-job: x86_64-mingw
try-job: i686-msvc
try-job: i686-mingw
Improve `Ord` violation help
Recent experience in #128083 showed that the panic message when an Ord violation is detected by the new sort implementations can be confusing. So this PR aims to improve it, together with minor bug fixes in the doc comments for sort*, sort_unstable* and select_nth_unstable*.
Is it possible to get these changes into the 1.81 release? It doesn't change behavior and would greatly help when users encounter this panic for the first time, which they may after upgrading to 1.81.
Tagging `@orlp`
Stabilize `min_exhaustive_patterns`
## Stabilisation report
I propose we stabilize the [`min_exhaustive_patterns`](https://github.com/rust-lang/rust/issues/119612) language feature.
With this feature, patterns of empty types are considered unreachable when matched by-value. This allows:
```rust
enum Void {}
fn foo() -> Result<u32, Void>;
fn main() {
let Ok(x) = foo();
// also
match foo() {
Ok(x) => ...,
}
}
```
This is a subset of the long-unstable [`exhaustive_patterns`](https://github.com/rust-lang/rust/issues/51085) feature. That feature is blocked because omitting empty patterns is tricky when *not* matched by-value. This PR stabilizes the by-value case, which is not tricky.
The not-by-value cases (behind references, pointers, and unions) stay as they are today, e.g.
```rust
enum Void {}
fn foo() -> Result<u32, &Void>;
fn main() {
let Ok(x) = foo(); // ERROR: missing `Err(_)`
}
```
The consequence on existing code is some extra "unreachable pattern" warnings. This is fully backwards-compatible.
### Comparison with today's rust
This proposal only affects match checking of empty types (i.e. types with no valid values). Non-empty types behave the same with or without this feature. Note that everything below is phrased in terms of `match` but applies equallly to `if let` and other pattern-matching expressions.
To be precise, a visibly empty type is:
- an enum with no variants;
- the never type `!`;
- a struct with a *visible* field of a visibly empty type (and no #[non_exhaustive] annotation);
- a tuple where one of the types is visibly empty;
- en enum with all variants visibly empty (and no `#[non_exhaustive]` annotation);
- a `[T; N]` with `N != 0` and `T` visibly empty;
- all other types are nonempty.
(An extra change was proposed below: that we ignore #[non_exhaustive] for structs since adding fields cannot turn an empty struct into a non-empty one)
For normal types, exhaustiveness checking requires that we list all variants (or use a wildcard). For empty types it's more subtle: in some cases we require a `_` pattern even though there are no valid values that can match it. This is where the difference lies regarding this feature.
#### Today's rust
Under today's rust, a `_` is required for all empty types, except specifically: if the matched expression is of type `!` (the never type) or `EmptyEnum` (where `EmptyEnum` is an enum with no variants), then the `_` is not required.
```rust
let foo: Result<u32, !> = ...;
match foo {
Ok(x) => ...,
Err(_) => ..., // required
}
let foo: Result<u32, &!> = ...;
match foo {
Ok(x) => ...,
Err(_) => ..., // required
}
let foo: &! = ...;
match foo {
_ => ..., // required
}
fn blah(foo: (u32, !)) {
match foo {
_ => ..., // required
}
}
unsafe {
let ptr: *const ! = ...;
match *ptr {} // allowed
let ptr: *const (u32, !) = ...;
match *ptr {
(x, _) => { ... } // required
}
let ptr: *const Result<u32, !> = ...;
match *ptr {
Ok(x) => { ... }
Err(_) => { ... } // required
}
}
```
#### After this PR
After this PR, a pattern of an empty type can be omitted if (and only if):
- the match scrutinee expression has type `!` or `EmptyEnum` (like before);
- *or* the empty type is matched by value (that's the new behavior).
In all other cases, a `_` is required to match on an empty type.
```rust
let foo: Result<u32, !> = ...;
match foo {
Ok(x) => ..., // `Err` not required
}
let foo: Result<u32, &!> = ...;
match foo {
Ok(x) => ...,
Err(_) => ..., // required because `!` is under a dereference
}
let foo: &! = ...;
match foo {
_ => ..., // required because `!` is under a dereference
}
fn blah(foo: (u32, !)) {
match foo {} // allowed
}
unsafe {
let ptr: *const ! = ...;
match *ptr {} // allowed
let ptr: *const (u32, !) = ...;
match *ptr {
(x, _) => { ... } // required because the matched place is under a (pointer) dereference
}
let ptr: *const Result<u32, !> = ...;
match *ptr {
Ok(x) => { ... }
Err(_) => { ... } // required because the matched place is under a (pointer) dereference
}
}
```
### Documentation
The reference does not say anything specific about exhaustiveness checking, hence there is nothing to update there. The nomicon does, I opened https://github.com/rust-lang/nomicon/pull/445 to reflect the changes.
### Tests
The relevant tests are in `tests/ui/pattern/usefulness/empty-types.rs`.
### Unresolved Questions
None that I know of.
try-job: dist-aarch64-apple
