Change how the `0` flag works in format!
Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.
Here's a short summary of how similar format strings work in Python and Rust:
```
:05 :<05 :>05 :^05
Python 3.6 |-0001| |-1000| |000-1| |0-100|
Rust before |-0001| |-1000| |-0001| |-0100|
Rust after |-0001| |-0001| |-0001| |-0001|
:#05x :<#05x :>#05x :^#05x
Python 3.6 |0x001| |0x100| |000x1| |00x10|
Rust before |0x001| |0x100| |000x1| |0x010|
Rust after |0x001| |0x001| |0x001| |0x001|
```
Fixes#39997 [breaking-change]
minor wording tweak to slice::{as_ptr, as_mut_ptr}
Per #37334, the slice-as-pointer methods mentioned that "modifying the slice may cause its buffer to be reallocated", when in fact modifying the *slice* itself would cause no such change. (It is a borrow, after all!) This is a tweak to the wording of that line to stress it's the *collection* that could cause the buffer to be reallocated.
r? @steveklabnik
Now it always implies right-alignment, so that padding zeroes are placed after the sign (if any) and before the digits. In other words, it always takes precedence over explicitly specified `[[fill]align]`. This also affects the '#' flag: zeroes are placed after the prefix (0b, 0o, 0x) and before the digits.
:05 :<05 :>05 :^05
before |-0001| |-1000| |-0001| |-0100|
after |-0001| |-0001| |-0001| |-0001|
:#05x :<#05x :>#05x :^#05x
before |0x001| |0x100| |000x1| |0x010|
after |0x001| |0x001| |0x001| |0x001|
Fixes#39997 [breaking-change]
Leftovers from #39594; From<Box> impls
These are a few more impls that follow the same reasoning as those from #39594.
What's included:
* `From<Box<str>> for String`
* `From<Box<[T]>> for Vec<T>`
* `From<Box<CStr>> for CString`
* `From<Box<OsStr>> for OsString`
* `From<Box<Path>> for PathBuf`
* `Into<Box<str>> for String`
* `Into<Box<[T]>> for Vec<T>`
* `Into<Box<CStr>> for CString`
* `Into<Box<OsStr>> for OsString`
* `Into<Box<Path>> for PathBuf`
* `<Box<CStr>>::into_c_string`
* `<Box<OsStr>>::into_os_string`
* `<Box<Path>>::into_path_buf`
* Tracking issue for latter three methods + three from previous PR.
Currently, the opposite direction isn't doable with `From` (only `Into`) because of the separation between `liballoc` and `libcollections`. I'm holding off on those for a later PR.
Added remove_from to vec.rs (#38143)
Turns out that if you push to someone's PR branch and cause the PR to close, you lose delegation 😞.
@madseagames I'm really sorry about that 😭
Reduce std_unicode’s public API
* Only keep one copy of the `UTF8_CHAR_WIDTH` table instead of one of each of libcore and libstd_unicode.
* Move the `utf8_char_width` function to `core::str` under the `str_internals` unstable feature.
* Remove `std_unicode::str::is_utf16`. It was only accessible through the `#[unstable]` crate std_unicode. It has never been used in the compiler or standard library since 47e7a05 added it in 2012 “for OS API interop”. It can be replaced with a one-liner:
```rust
fn is_utf16(slice: &[u16]) -> bool {
std::char::decode_utf16(s).all(|r| r.is_ok())
}
```
Panic on errors in `format!` or `<T: Display>::to_string`
… instead of silently ignoring a result.
`fmt::Write for String` never returns `Err`, so implementations of `Display` (or other traits of that family) never should either.
Fixes#40103
… instead of silently ignoring a result.
`fmt::Write for String` never returns `Err`,
so implementations of `Display` (or other traits of that family)
never should either.
Fixes#40103
impl RangeArgument for RangeInclusive and add appropriate tests
Now that `RangeArgument` returns a `Bound`, the impl for `RangeInclusive` is natural to implement and all that's required are tests around it.
Update std::fmt module docs for landing of #33642.
Since #33642, it's no longer true that all references to a given format argument must use the same type. The docs don't seem to have been updated.
1. Clarify that `String::split_off` returns one string and modifies self
in-place. The documentation implied that it returns two new strings.
2. Make the documentation mirror `Vec::split_off`.
