Remove no longer necessary comparison to Vec::splice.
`String::replace_range` was previously called `String::splice`, so this
note was necessary to differentiate it from the `Vec` method. Now that
it's renamed, this note no longer seems necessary.
`String::replace_range` was previously called `String::splice`, so this
note was necessary to differentiate it from the `Vec` method. Now that
it's renamed, this note no longer seems necessary.
std: Minimize size of panicking on wasm
This commit applies a few code size optimizations for the wasm target to
the standard library, namely around panics. We notably know that in most
configurations it's impossible for us to print anything in
wasm32-unknown-unknown so we can skip larger portions of panicking that
are otherwise simply informative. This allows us to get quite a nice
size reduction.
Finally we can also tweak where the allocation happens for the
`Box<Any>` that we panic with. By only allocating once unwinding starts
we can reduce the size of a panicking wasm module from 44k to 350 bytes.
Inline most of the code paths for conversions with boxed slices
This helps with the specific problem described in #49541, obviously without making any large change to how inlining works in the general case.
Everything involved in the conversions is made `#[inline]`, except for the `<Vec<T>>::into_boxed_slice` entry point which is made `#[inline(always)]` after checking that duplicating the function mentioned in the issue prevented its inlining if I only annotate it with
`#[inline]`.
For the record, that function was:
```rust
pub fn foo() -> Box<[u8]> {
vec![0].into_boxed_slice()
}
```
To help the inliner's job, we also hoist a `self.capacity() != self.len` check in `<Vec<T>>::shrink_to_fit` and mark it as `#[inline]` too.
Replace manual iterator exhaust with for_each(drop)
This originally added a dedicated method, `Iterator::exhaust`, and has since been replaced with `for_each(drop)`, which is more idiomatic.
<del>This is just shorthand for `for _ in &mut self {}` or `while let Some(_) = self.next() {}`. This states the intent a lot more clearly than the identical code: run the iterator to completion.
<del>At least personally, my eyes tend to gloss over `for _ in &mut self {}` without fully paying attention to what it does; having a `Drop` implementation akin to:
<del>`for _ in &mut self {}; unsafe { free(self.ptr); }`</del>
<del>Is not as clear as:
<del>`self.exhaust(); unsafe { free(self.ptr); }`
<del>Additionally, I've seen debate over whether `while let Some(_) = self.next() {}` or `for _ in &mut self {}` is more clear, whereas `self.exhaust()` is clearer than both.
Some modules were still using the deprecated `allocator` module, use the
`alloc` module instead.
Some modules were using `super` while it's not needed.
Some modules were more or less ordering them, and other not, so the
latter have been modified to match the others.
Create one canonical location which panics with "capacity overflow" instead of
having many. This reduces the size of a `panic!("{}", 1)` binary on wasm from
34k to 17k.
Deprecate offset_to; switch core&alloc to using offset_from instead
Bonus: might make code than uses `.len()` on slice iterators faster
cc https://github.com/rust-lang/rust/issues/41079
Merge the std_unicode crate into the core crate
[The standard library facade](https://github.com/rust-lang/rust/issues/27783) has historically contained a number of crates with different roles, but that number has decreased over time. `rand` and `libc` have moved to crates.io, and [`collections` was merged into `alloc`](https://github.com/rust-lang/rust/pull/42648). Today we have `core` that applies everywhere, `std` that expects a full operating system, and `alloc` in-between that only requires a memory allocator (which can be provided by users)… and `std_unicode`, which doesn’t really have a reason to be separate anymore. It contains functionality based on Unicode data tables that can be large, but as long as relevant functions are not called the tables should be removed from binaries by linkers.
This deprecates the unstable `std_unicode` crate and moves all of its contents into `core`, replacing them with `pub use` reexports. The crate can be removed later. This also removes the `CharExt` trait (replaced with inherent methods in libcore) and `UnicodeStr` trait (merged into `StrExt`). There traits were both unstable and not intended to be used or named directly.
A number of new items are newly-available in libcore and instantly stable there, but only if they were already stable in libstd.
Fixes#49319.
Use sort_by_cached_key where appropriate
A follow-up to https://github.com/rust-lang/rust/pull/48639, converting various slice sorting calls to `sort_by_cached_key` when the key functions are more expensive.
Rollup of 9 pull requests
Successful merges:
- #48658 (Add a generic CAS loop to std::sync::Atomic*)
- #49253 (Take the original extra-filename passed to a crate into account when resolving it as a dependency)
- #49345 (RFC 2008: Finishing Touches)
- #49432 (Flush executables to disk after linkage)
- #49496 (Add more vec![... ; n] optimizations)
- #49563 (add a dist builder to build rust-std components for the THUMB targets)
- #49654 (Host compiler documentation: Include private items)
- #49667 (Add more features to rust_2018_preview)
- #49674 (ci: Remove x86_64-gnu-incremental builder)
Failed merges:
Add more vec![... ; n] optimizations
vec![0; n], via implementations of SpecFromElem, has an optimization that uses with_capacity_zeroed instead of with_capacity, which will use calloc instead of malloc, and avoid an extra memset.
This PR adds the same optimization for ptr::null, ptr::null_mut, and None, when their in-memory representation is zeroes.
Introduce Vec::resize_with method (see #41758)
In #41758, the libs team decided they preferred `Vec::resize_with` over `Vec::resize_default()`. Here is an implementation to get this moving forward.
I don't know what the removal process for `Vec::resize_default()` should be, so I've left it in place for now. Would be happy to follow up with its removal.
