This feature is intended to provide expensive but thorough help for
developers who have an unexpected `TypeId` value and need to determine
what type it actually is. It causes `impl Debug for TypeId` to print
the type name in addition to the opaque ID hash, and in order to do so,
adds a name field to `TypeId`. The cost of this is the increased size of
`TypeId` and the need to store type names in the binary; therefore, it
is an optional feature.
It may be enabled via `cargo -Zbuild-std -Zbuild-std-features=debug_typeid`.
(Note that `-Zbuild-std-features` disables default features which you
may wish to reenable in addition; see
<https://doc.rust-lang.org/cargo/reference/unstable.html#build-std-features>.)
Example usage and output:
```
fn main() {
use std::any::{Any, TypeId};
dbg!(TypeId::of::<usize>(), drop::<usize>.type_id());
}
```
```
TypeId::of::<usize>() = TypeId(0x763d199bccd319899208909ed1a860c6 = usize)
drop::<usize>.type_id() = TypeId(0xe6a34bd13f8c92dd47806da07b8cca9a = core::mem::drop<usize>)
```
Also added feature declarations for the existing `debug_refcell` feature
so it is usable from the `rust.std-features` option of `config.toml`.
This fixes the issues described in
https://github.com/rust-lang/rust/issues/136102. Primarily, this
resolves some issues with how the documentation for the prelude is
generated:
- It avoids showing "unstable" for macros in the prelude that are
actually stable.
- Avoids duplication of some pages due to the previous lack of
`doc(no_inline)`.
- Makes the different edition preludes consistent, and sets a pattern
that can be used by future editions.
We may need to rearrange these modules in the future if we decide to
remove anything from the prelude again. If we do, I think we should look
into a different solution that avoids the documentation problems.
Update docs for impl keyword
This started as a fix for #79878, but also introduces some structure (headings), and elaborates a tiny bit on impl Trait syntax.
Improve examples for file locking
The `lock` and `try_lock` documentation states that "if the file not open for writing, it is unspecified whether this function returns an error." With this change, the examples use `File::create` instead of `File::open`, eliminating the possibility of someone blindly copying code with unspecified behavior.
rustfmt fails to format this match expression, because it has several
long string literals over the maximum line width. This seems to exhibit
rustfmt issues #3863 (Gives up on chains if any line is too long) and
#3156 (Fail to format match arm when other arm has long line).
Introduce CoercePointeeWellformed for coherence checks at typeck stage
Fix#135206
This is the first PR to introduce the "wellformedness" check for `derive(CoercePointee)`.
This patch introduces a new error code to cover all the prerequisites of the said macro. The checks that is enforced with this patch is whether the data is indeed `struct` and whether the layout is set to `repr(transparent)`.
A following series of patch will arrive later to address the following concern.
1. #135217 so that we would only admit one single coercion on one type parameter, and leave the rest for future consideration in tandem of development of other coercion rules.
1. Enforcement of data field requirements.
**An open question** is whether there is a good schema to encode the `#[pointee]` as well, so that we could also check if the `#[pointee]` type parameter is indeed `?Sized`.
``@rustbot`` label F-derive_coerce_pointee
Some miscellaneous edition-related library tweaks
Some library edition tweaks that can be done separately from upgrading the whole standard library to edition 2024 (which is blocked on getting the submodules upgraded, for example)
Use an `Option` for `FindNextFileHandle` in `ReadDir` instead of `INVALID_FILE_HANDLE` sentinel value
Sometimes we store an invalid handle when we don't want to return an error. We then check the handle before use in order to avoid actually using the invalid handle. However, using an `Option` for this is better and avoids us forgetting to check the handle is valid. This was noticed due to us closing the handle without checking for validity: bd6a6777f5/library/std/src/sys/pal/windows/fs.rs (L148-L151)
fix(libtest): Enable Instant on Emscripten targets
`Instant::now()` works correctly on Emscripten since https://github.com/rust-lang/libc/pull/3962. All wasm-family targets with OS support can now handle instants.
Improves #131738.
~~This changes the behavior of libtest on `unknown-unknown`/`unknown-none` wasm targets, but as far as I can see, libtest doesn't support them anyway. (Can anyone double-check?)~~ UPD: this patch no longer affects `unknown-unknown` targets.
``@rustbot`` label +A-libtest +T-testing-devex +O-emscripten +O-wasm -needs-triage
Update bootstrap compiler and rustfmt
The rustfmt version we previously used formats things differently from what the latest nightly rustfmt does. This causes issues for subtrees that get formatted both in-tree and in their own repo. Updating the rustfmt used in-tree solves those issues. Also bumped the bootstrap compiler as the stage0 update command always updates both at the same
time.
Rollup of 5 pull requests
Successful merges:
- #134679 (Windows: remove readonly files)
- #136213 (Allow Rust to use a number of libc filesystem calls)
- #136530 (Implement `x perf` directly in bootstrap)
- #136601 (Detect (non-raw) borrows of null ZST pointers in CheckNull)
- #136659 (Pick the max DWARF version when LTO'ing modules with different versions )
r? `@ghost`
`@rustbot` modify labels: rollup
Make `AsyncFnOnce`, `AsyncFnMut`, `AsyncFn` non-`#[fundamental]`
Address the issue #136723 on nightly (the issue will only *actually* be fixed with a beta backport).
Document `Sum::sum` returns additive identities for `[]`
Because the neutral element of `<fNN as iter::Sum>` was changed to `neg_zero`, the documentation needed to be updated, as it was reporting inadequate information about what should be expected from the return.
Relevant Commit: 4908188518
Relevant Pull Request: https://github.com/rust-lang/rust/pull/129321
---
The referenced commit causes unintended side effects on presentation layer applications like using Tera templates, for example. I'm not sure what the motivation was behind the original change, but it seems like more discussion should be put into this issue and potentially have that change reverted.
Clean up `HashMap` and `HashSet` docs.
This commit makes some small, pedantic changes to the docs for `HashMap` and `HashSet`, which fixes that:
* "HashMap" is not always formatted as code (as in `HashMap`), and that
* `HashSet` sometimes references `HashMap` instead of itself.
Detect (non-raw) borrows of null ZST pointers in CheckNull
Fixes#136568. Ensures that we check that borrows of derefs are non-null in the `CheckNull` pass **even if** it's a ZST pointee.
I'm actually surprised that this is UB in Miri, but if it's certainly UB, then this PR modifies the null check to be stricter. I couldn't find anywhere in https://doc.rust-lang.org/reference/behavior-considered-undefined.html that discusses this case specifically, but I didn't read it too closely, or perhaps it's just missing a bullet point.
On the contrary, if this is actually erroneous UB in Miri, then I'm happy to close this (and perhaps fix the null check in Miri to exclude ZSTs?)
On the double contrary, if this is still an "open question", I'm also happy to close this and wait for a decision to be made.
r? ``@saethlin`` cc ``@RalfJung`` (perhaps you feel strongly about this change)
