The current example of a spinlock was not correct. The lock is actually acquired
when old == result. So we only need to deschedule when this is not the case.
Similar to the stability attributes, a type annotated with `#[must_use =
"informative snippet"]` will print the normal warning message along with
"informative snippet". This allows the type author to provide some
guidance about why the type should be used.
---
It can be a little unintuitive that something like `v.iter().map(|x|
println!("{}", x));` does nothing: the majority of the iterator adaptors
are lazy and do not execute anything until something calls `next`, e.g.
a `for` loop, `collect`, `fold`, etc.
The majority of such errors can be seen by someone writing something
like the above, i.e. just calling an iterator adaptor and doing nothing
with it (and doing this is certainly useless), so we can co-opt the
`must_use` lint, using the message functionality to give a hint to the
reason why.
Fixes#14666.
It can be a little unintuitive that something like `v.iter().map(|x|
println!("{}", x));` does nothing: the majority of the iterator adaptors
are lazy and do not execute anything until something calls `next`, e.g.
a `for` loop, `collect`, `fold`, etc.
The majority of such errors can be seen by someone writing something
like the above, i.e. just calling an iterator adaptor and doing nothing
with it (and doing this is certainly useless), so we can co-opt the
`must_use` lint, using the message functionality to give a hint to the
reason why.
Fixes#14666.
Add libunicode; move unicode functions from core
- created new crate, libunicode, below libstd
- split `Char` trait into `Char` (libcore) and `UnicodeChar` (libunicode)
- Unicode-aware functions now live in libunicode
- `is_alphabetic`, `is_XID_start`, `is_XID_continue`, `is_lowercase`,
`is_uppercase`, `is_whitespace`, `is_alphanumeric`, `is_control`, `is_digit`,
`to_uppercase`, `to_lowercase`
- added `width` method in UnicodeChar trait
- determines printed width of character in columns, or None if it is a non-NULL control character
- takes a boolean argument indicating whether the present context is CJK or not (characters with 'A'mbiguous widths are double-wide in CJK contexts, single-wide otherwise)
- split `StrSlice` into `StrSlice` (libcore) and `UnicodeStrSlice` (libunicode)
- functionality formerly in `StrSlice` that relied upon Unicode functionality from `Char` is now in `UnicodeStrSlice`
- `words`, `is_whitespace`, `is_alphanumeric`, `trim`, `trim_left`, `trim_right`
- also moved `Words` type alias into libunicode because `words` method is in `UnicodeStrSlice`
- unified Unicode tables from libcollections, libcore, and libregex into libunicode
- updated `unicode.py` in `src/etc` to generate aforementioned tables
- generated new tables based on latest Unicode data
- added `UnicodeChar` and `UnicodeStrSlice` traits to prelude
- libunicode is now the collection point for the `std::char` module, combining the libunicode functionality with the `Char` functionality from libcore
- thus, moved doc comment for `char` from `core::char` to `unicode::char`
- libcollections remains the collection point for `std::str`
The Unicode-aware functions that previously lived in the `Char` and `StrSlice` traits are no longer available to programs that only use libcore. To regain use of these methods, include the libunicode crate and `use` the `UnicodeChar` and/or `UnicodeStrSlice` traits:
extern crate unicode;
use unicode::UnicodeChar;
use unicode::UnicodeStrSlice;
use unicode::Words; // if you want to use the words() method
NOTE: this does *not* impact programs that use libstd, since UnicodeChar and UnicodeStrSlice have been added to the prelude.
closes#15224
[breaking-change]
Extend the null ptr optimization to work with slices, closures, procs, & trait objects by using the internal pointers as the discriminant.
This decreases the size of `Option<&[int]>` (and similar) by one word.
- created new crate, libunicode, below libstd
- split Char trait into Char (libcore) and UnicodeChar (libunicode)
- Unicode-aware functions now live in libunicode
- is_alphabetic, is_XID_start, is_XID_continue, is_lowercase,
is_uppercase, is_whitespace, is_alphanumeric, is_control,
is_digit, to_uppercase, to_lowercase
- added width method in UnicodeChar trait
- determines printed width of character in columns, or None if it is
a non-NULL control character
- takes a boolean argument indicating whether the present context is
CJK or not (characters with 'A'mbiguous widths are double-wide in
CJK contexts, single-wide otherwise)
- split StrSlice into StrSlice (libcore) and UnicodeStrSlice
(libunicode)
- functionality formerly in StrSlice that relied upon Unicode
functionality from Char is now in UnicodeStrSlice
- words, is_whitespace, is_alphanumeric, trim, trim_left, trim_right
- also moved Words type alias into libunicode because words method is
in UnicodeStrSlice
- unified Unicode tables from libcollections, libcore, and libregex into
libunicode
- updated unicode.py in src/etc to generate aforementioned tables
- generated new tables based on latest Unicode data
- added UnicodeChar and UnicodeStrSlice traits to prelude
- libunicode is now the collection point for the std::char module,
combining the libunicode functionality with the Char functionality
from libcore
- thus, moved doc comment for char from core::char to unicode::char
- libcollections remains the collection point for std::str
The Unicode-aware functions that previously lived in the Char and
StrSlice traits are no longer available to programs that only use
libcore. To regain use of these methods, include the libunicode crate
and use the UnicodeChar and/or UnicodeStrSlice traits:
extern crate unicode;
use unicode::UnicodeChar;
use unicode::UnicodeStrSlice;
use unicode::Words; // if you want to use the words() method
NOTE: this does *not* impact programs that use libstd, since UnicodeChar
and UnicodeStrSlice have been added to the prelude.
closes#15224
[breaking-change]
This will break code that used the old `Index` trait. Change this code
to use the new `Index` traits. For reference, here are their signatures:
pub trait Index<Index,Result> {
fn index<'a>(&'a self, index: &Index) -> &'a Result;
}
pub trait IndexMut<Index,Result> {
fn index_mut<'a>(&'a mut self, index: &Index) -> &'a mut Result;
}
Closes#6515.
[breaking-change]
The current implementation of `rotate_left` and `rotate_right` are incorrect when the rotation amount is 0, or a multiple of the input's bitsize. When `n = 0`, the expression
(self >> n) | (self << ($BITS - n))
results in a shift left by `$BITS` bits, which is undefined behavior (see https://github.com/rust-lang/rust/issues/10183), and currently results in a hardcoded `-1` value, instead of the original input value. Reducing `($BITS - n)` modulo `$BITS`, simplified to `(-n % $BITS)`, fixes this problem.
Being able to index into the bytes of a string encourages
poor UTF-8 hygiene. To get a view of `&[u8]` from either
a `String` or `&str` slice, use the `as_bytes()` method.
Closes#12710.
[breaking-change]
This does two things:
* Reorganizes the declaration order to be more readable, less random.
* Removes the `slice::traits` module, a public module that does nothing but declare impls of `cmp` traits.
Closes#14358.
~~The tests are not yet moved to `utf16_iter`, so this probably won't compile. I'm submitting this PR anyway so it can be reviewed and since it was mentioned in #14611.~~ EDIT: Tests now use `utf16_iter`.
This deprecates `.to_utf16`. `x.to_utf16()` should be replaced by either `x.utf16_iter().collect::<Vec<u16>>()` (the type annotation may be optional), or just `x.utf16_iter()` directly, if it can be used in an iterator context.
[breaking-change]
cc @huonw
This deprecates `.to_utf16`. `x.to_utf16()` should be replaced by either
`x.utf16_units().collect::<Vec<u16>>()` (the type annotation may be optional), or
just `x.utf16_units()` directly, if it can be used in an iterator context.
Closes#14358
[breaking-change]
I ended up altering the semantics of Json's PartialOrd implementation.
It used to be the case that Null < Null, but I can't think of any reason
for an ordering other than the default one so I just switched it over to
using the derived implementation.
This also fixes broken `PartialOrd` implementations for `Vec` and
`TreeMap`.
# Note
This isn't ready to merge yet since libcore tests are broken as you end up with 2 versions of `Option`. The rest should be reviewable though.
RFC: 0028-partial-cmp
I ended up altering the semantics of Json's PartialOrd implementation.
It used to be the case that Null < Null, but I can't think of any reason
for an ordering other than the default one so I just switched it over to
using the derived implementation.
This also fixes broken `PartialOrd` implementations for `Vec` and
`TreeMap`.
RFC: 0028-partial-cmp
The bug #11084 causes `option::collect` and `result::collect` about twice as slower as it should because llvm is having some trouble optimizing away the scan closure. This gets rid of it so now those functions perform equivalent to a hand written version.
This also adds an impl of `Default` for `Rc` along the way.
Libcore's test infrastructure is complicated by the fact that many lang
items are defined in the crate. The current approach (realcore/realstd
imports) is hacky and hard to work with (tests inside of core::cmp
haven't been run for months!).
Moving tests to a separate crate does mean that they can only test the
public API of libcore, but I don't feel that that is too much of an
issue. The only tests that I had to get rid of were some checking the
various numeric formatters, but those are also exercised through normal
format! calls in other tests.
The bug #11084 causes these collect functions to run about
twice as slow as they should because llvm is having trouble
optimizing away the closure for some reason. This patch works
around that performance bug by using a simple adapter iterator
explicitly for capturing if the outer iterator returns an
error.
floating point numbers for real.
This will break code that looks like:
let mut x = 0;
while ... {
x += 1;
}
println!("{}", x);
Change that code to:
let mut x = 0i;
while ... {
x += 1;
}
println!("{}", x);
Closes#15201.
[breaking-change]
This change registers new snapshots, allowing `*T` to be removed from the language. This is a large breaking change, and it is recommended that if compiler errors are seen that any FFI calls are audited to determine whether they should be actually taking `*mut T`.
This can break code that looked like:
impl Foo for Box<Any> {
fn f(&self) { ... }
}
let x: Box<Any + Send> = ...;
x.f();
Change such code to:
impl Foo for Box<Any> {
fn f(&self) { ... }
}
let x: Box<Any> = ...;
x.f();
That is, upcast before calling methods.
This is a conservative solution to #5781. A more proper treatment (see
the xfail'd `trait-contravariant-self.rs`) would take variance into
account. This change fixes the soundness hole.
Some library changes had to be made to make this work. In particular,
`Box<Any>` is no longer showable, and only `Box<Any+Send>` is showable.
Eventually, this restriction can be lifted; for now, it does not prove
too onerous, because `Any` is only used for propagating the result of
task failure.
This patch also adds a test for the variance inference work in #12828,
which accidentally landed as part of DST.
Closes#5781.
[breaking-change]
This change starts denying `*T` in the parser. All code using `*T` should ensure
that the FFI call does indeed take `const T*` on the other side before renaming
the type to `*const T`.
Otherwise, all code can rename `*T` to `*const T`.
[breaking-change]
This will break code like:
fn f(x: &mut int) {}
let mut a = box 1i;
f(a);
Change it to:
fn f(x: &mut int) {}
let mut a = box 1i;
f(&mut *a);
RFC 33; issue #10504.
[breaking-change]
The f128 type has very little support in the compiler and the feature is
basically unusable today. Supporting half-baked features in the compiler can be
detrimental to the long-term development of the compiler, and hence this feature
is being removed.
