remove `feature(inline_const_pat)`
Summarizing https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/remove.20feature.28inline_const_pat.29.20and.20shared.20borrowck.
With https://github.com/rust-lang/types-team/issues/129 we will start to borrowck items together with their typeck parent. This is necessary to correctly support opaque types, blocking the new solver and TAIT/ATPIT stabilization with the old one. This means that we cannot really support `inline_const_pat` as they are implemented right now:
- we want to typeck inline consts together with their parent body to allow inference to flow both ways and to allow the const to refer to local regions of its parent.This means we also need to borrowck the inline const together with its parent as that's necessary to properly support opaque types
- we want the inline const pattern to participate in exhaustiveness checking
- to participate in exhaustiveness checking we need to evaluate it, which requires borrowck, which now relies on borrowck of the typeck root, which ends up checking exhaustiveness again. **This is a query cycle**.
There are 4 possible ways to handle this:
- stop typechecking inline const patterns together with their parent
- causes inline const patterns to be different than inline const exprs
- prevents bidirectional inference, we need to either fail to compile `if let const { 1 } = 1u32` or `if let const { 1u32 } = 1`
- region inference for inline consts will be harder, it feels non-trivial to support inline consts referencing local regions from the parent fn
- inline consts no longer participate in exhaustiveness checking. Treat them like `pat if pat == const { .. }` instead. We then only evaluate them after borrowck
- difference between `const { 1 }` and `const FOO: usize = 1; match x { FOO => () }`. This is confusing
- do they carry their weight if they are now just equivalent to using an if-guard
- delay exhaustiveness checking until after borrowck
- should be possible in theory, but is a quite involved change and may have some unexpected challenges
- remove this feature for now
I believe we should either delay exhaustiveness checking or remove the feature entirely. As moving exhaustiveness checking to after borrow checking is quite complex I think the right course of action is to fully remove the feature for now and to add it again once/if we've got that implementation figured out.
`const { .. }`-expressions remain stable. These seem to have been the main motivation for https://github.com/rust-lang/rfcs/issues/2920.
r? types
cc `@rust-lang/types` `@rust-lang/lang` #76001
Remove mention of `exhaustive_patterns` from `never` docs
The example shows an exhaustive match:
```rust
#![feature(exhaustive_patterns)]
use std::str::FromStr;
let Ok(s) = String::from_str("hello");
```
But https://github.com/rust-lang/rust/issues/119612 moved this functionality to `#![feature(min_exhaustive_patterns)` and then stabilized it.
Switch some rustc_on_unimplemented uses to diagnostic::on_unimplemented
The use on the SliceIndex impl appears unreachable, there is no mention of "vector indices" in any test output and I could not get it to show up in error messages.
Simplify expansion for format_args!().
Instead of calling `Placeholder::new()`, we can just use a struct expression directly.
Before:
```rust
Placeholder::new(…, …, …, …)
```
After:
```rust
Placeholder {
position: …,
flags: …,
width: …,
precision: …,
}
```
(I originally avoided the struct expression, because `Placeholder` had a lot of fields. But now that https://github.com/rust-lang/rust/pull/136974 is merged, it only has four fields left.)
This will make the `fmt` argument to `fmt::Arguments::new_v1_formatted()` a candidate for const promotion, which is important if we ever hope to tackle https://github.com/rust-lang/rust/issues/92698 (It doesn't change anything yet though, because the `args` argument to `fmt::Arguments::new_v1_formatted()` is not const-promotable.)
Instead of calling new(), we can just use a struct expression directly.
Before:
Placeholder::new(…, …, …, …)
After:
Placeholder {
position: …,
flags: …,
width: …,
precision: …,
}
std: deduplicate `errno` accesses
By marking `__errno_location` as `#[ffi_const]` and `std::sys::os::errno` as `#[inline]`, this PR allows merging multiple calls to `io::Error::last_os_error()` into one.
Start using `with_native_path` in `std::sys::fs`
Ideally, each platform should use their own native path type internally. This will, for example, allow passing a `CStr` directly to `std::fs::File::open` and therefore avoid the need for allocating a new null-terminated C 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 PR does some minimal refactoring which should help progress towards that goal. The changes are Unix-only and even then I avoided functions that require more changes so that this PR is just moving things around.
r? joboet
stabilize const_cell
``@rust-lang/libs-api`` ``@rust-lang/wg-const-eval`` I see no reason to wait any longer, so I propose we stabilize the use of `Cell` in `const fn` -- specifically the APIs listed here:
```rust
// core::cell
impl<T> Cell<T> {
pub const fn replace(&self, val: T) -> T;
}
impl<T: Copy> Cell<T> {
pub const fn get(&self) -> T;
}
impl<T: ?Sized> Cell<T> {
pub const fn get_mut(&mut self) -> &mut T;
pub const fn from_mut(t: &mut T) -> &Cell<T>;
}
impl<T> Cell<[T]> {
pub const fn as_slice_of_cells(&self) -> &[Cell<T>];
}
```
Unfortunately, `set` cannot be made `const fn` yet as it drops the old contents.
Fixes https://github.com/rust-lang/rust/issues/131283
Change the syntax of the internal `weak!` macro
Change the syntax to include parameter names and a trailing semicolon.
Motivation:
- Mirror the `syscall!` macro.
- Allow rustfmt to format it (when wrapped in parentheses, and when not inside `cfg_if!`).
- For better documentation (having the parameter names available in the source code is a bit nicer).
- Allow a future improvement to this macro where we can sometimes use the symbol directly when it's statically known to be available (and thus need the parameter names to be available), see https://github.com/rust-lang/rust/pull/136868.
r? libs
By marking `__errno_location` as `#[ffi_const]` and `std::sys::os::errno` as `#[inline]`, this PR allows merging multiple calls to `io::Error::last_os_error()` into one.
Change the syntax to include parameter names and a trailing semicolon.
Motivation:
- Mirror the `syscall!` macro.
- Allow rustfmt to format it (when wrapped in parentheses).
- For better documentation (having the parameter names available in
the source code is a bit nicer).
- Allow future improvements to this macro where we can sometimes use the
symbol directly when it's statically known to be available.
Override PartialOrd methods for bool
I noticed that `PartialOrd` implementation for `bool` does not override the individual operator methods, unlike the other primitive types like `char` and integers.
This commit extracts these `PartialOrd` overrides shared by the other primitive types into a macro and calls it on `bool` too.
CC `@scottmcm` for our recent adventures in `PartialOrd` land
Trusty: Fix build for anonymous pipes and std::sys::process
PRs #136842 (Add libstd support for Trusty targets), #137793 (Stablize anonymous pipe), and #136929 (std: move process implementations to `sys`) merged around the same time, so update Trusty to take them into account.
cc `@randomPoison`
add FCW to warn about wasm ABI transition
See https://github.com/rust-lang/rust/issues/122532 for context: the "C" ABI on wasm32-unk-unk will change. The goal of this lint is to warn about any function definition and calls whose behavior will be affected by the change. My understanding is the following:
- scalar arguments are fine
- including 128 bit types, they get passed as two `i64` arguments in both ABIs
- `repr(C)` structs (recursively) wrapping a single scalar argument are fine (unless they have extra padding due to over-alignment attributes)
- all return values are fine
`@bjorn3` `@alexcrichton` `@Manishearth` is that correct?
I am making this a "show up in future compat reports" lint to maximize the chances people become aware of this. OTOH this likely means warnings for most users of Diplomat so maybe we shouldn't do this?
IIUC, wasm-bindgen should be unaffected by this lint as they only pass scalar types as arguments.
Tracking issue: https://github.com/rust-lang/rust/issues/138762
Transition plan blog post: https://github.com/rust-lang/blog.rust-lang.org/pull/1531
try-job: dist-various-2
I noticed that `PartialOrd` implementation for `bool` does not override the
individual operator methods, unlike the other primitive types like `char`
and integers.
This commit extracts these `PartialOrd` overrides shared by the other
primitive types into a macro and calls it on `bool` too.
remove remnants of const_box feature
This feature requires major design work, and the few methods it gates currently aren't actually useful. Let's reset to a clean slate so when a design materializes, we can start from scratch.
Closes https://github.com/rust-lang/rust/issues/92521 by removing the feature it tracks.
r? ````@oli-obk````
Implement some basics in UEFI fs
- Just getting some basics out of the way while waiting for #138236 to be merged.
- Adds `fs::canonicalize`. Should be same as absolute in case of UEFI since there is no symlink support and absolute path is guaranteed to be uniqe according to spec.
- Make `fs::lstat` same as `fs::stat`. Should be same since UEFI does not have symlink support.
- Implement `OptionOptions`.
cc ````@nicholasbishop```` ````@dvdhrm````
UEFI does not have specific modes for create_new, truncate and append.
So those need to to be simulated after opening the file.
Signed-off-by: Ayush Singh <ayush@beagleboard.org>
- Should be same as absolute in UEFI since there are no symlinks.
- Also each absolute path representation should be unique according to
the UEFI specification.
Signed-off-by: Ayush Singh <ayush@beagleboard.org>
PRs #136842 (Add libstd support for Trusty targets), #137793 (Stablize
anonymous pipe), and #136929 (std: move process implementations to
`sys`) merged around the same time, so update Trusty to take them into
account.
bors