core: Add `BorrowedCursor::with_unfilled_buf`
Implementation of https://github.com/rust-lang/libs-team/issues/367.
This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`.
Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly.
Cc rust-lang/rust#78485rust-lang/rust#117693
Updates to random number generation APIs
Updates based on discussions about random number generation.
- Add comment on `RandomSource::fill_bytes` about multiple calls, to allow
efficient implementations for random sources that generate a word at a time.
- Drop the `Random` trait in favor of `Distribution<T>`, which will let people
make calls like random(1..=6), and which allows for future expansion to
non-uniform distributions, as well as floating-point. (For now, this is only
implemented for `RangeFull`, to get the interface in place. Subsequent PRs
will implement it for other range types.)
make `cfg_select` a builtin macro
tracking issue: https://github.com/rust-lang/rust/issues/115585
This parses mostly the same as the `macro cfg_select` version, except:
1. wrapping in double brackets is no longer supported (or needed): `cfg_select {{ /* ... */ }}` is now rejected.
2. in an expression context, the rhs is no longer wrapped in a block, so that this now works:
```rust
fn main() {
println!(cfg_select! {
unix => { "foo" }
_ => { "bar" }
});
}
```
3. a single wildcard rule is now supported: `cfg_select { _ => 1 }` now works
I've also added an error if none of the rules evaluate to true, and warnings for any arms that follow the `_` wildcard rule.
cc `@traviscross` if I'm missing any feature that should/should not be included
r? `@petrochenkov` for the macro logic details
constify `From` and `Into`
tracking issue rust-lang/rust#143773
r? ``````@fee1-dead``````
I did not mark any impls elsewhere as `const`, those can happen on their own timeframe and don't need to be part of this MVP. But if there are some core ones you think should be in there I'll happily add them, just couldn't think of any
New tracking issues for const_ops and const_cmp
Let's do a clean start with new tracking issues to avoid mixing things up with the previous constification.
I assume the fact that the `PartialEq` *trait* and *impls* used different feature names was a mistake (the feature name on the impl is entirely irrelevant anyway).
Part of https://github.com/rust-lang/rust/issues/143800, https://github.com/rust-lang/rust/issues/143802
r? ``@oli-obk``
This will let people make calls like random(1..=6), and allows for
future expansion to non-uniform distributions, as well as
floating-point.
For now, this is only implemented for `RangeFull`, to get the interface
in place. Subsequent commits will implement it for other range types.
Constify `Fn*` traits
r? `@compiler-errors` `@fee1-dead`
this should unlock a few things. A few `const_closures` tests have broken even more than before, but that feature is marked as incomplete anyway
cc rust-lang/rust#67792
docs: document trait upcasting rules in `Unsize` trait
The trait upcasting feature stabilized in 1.86 added new `Unsize` implementation, but this wasn't reflected in the trait's documentation.
doc(std): clarify `NonZero<T>` usage limitation in doc comment
Closesrust-lang/rust#142966
This PR clarifies `NonZero<T>` usage limitation in doc comment and fixes a typo.
r? libs
lib: more eagerly return `self.len()` from `ceil_char_boundary`
There is no reason to go through the complicated branch as it would
always return `self.len()` in this case. Also helps debug code somewhat
and I guess might make optimizations easier (although I haven't really a
sample to demonstrate this.)
ref. https://github.com/rust-lang/rust/issues/93743
Suggested by `@chrisduerr`
There is no reason to go through the complicated branch as it would
always return `self.len()` in this case. Also helps debug code somewhat
and I guess might make optimizations easier (although I haven't really a
sample to demonstrate this.)
ref. #93743
Suggested by @chrisduerr
use `is_multiple_of` and `div_ceil`
In tricky logic, these functions are much more informative than the manual implementations. They also catch subtle bugs:
- the manual `is_multiple_of` often does not handle division by zero
- manual `div_ceil` often does not consider overflow
The transformation is free for `is_multiple_of` if the divisor is compile-time known to be non-zero. For `div_ceil` there is a small cost to considering overflow. Here is some assembly https://godbolt.org/z/5zP8KaE1d.
move `va_copy`, `va_arg` and `va_end` to `core::intrinsics`
some questions:
- should these functions be `pub`?
- is a separate module justified?
r? `@RalfJung`
