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.
FusedIterator is a marker trait that promises that the implementing
iterator continues to return `None` from `.next()` once it has returned
`None` once (and/or `.next_back()`, if implemented).
The effects of FusedIterator are already widely available through
`.fuse()`, but with stable `FusedIterator`, stable Rust users can
implement this trait for their iterators when appropriate.
The docs currently say, "If the closure returns false, it will try
again, and call the closure on the next element." But this happens
regardless of whether the closure returns true or false.
Make core::ops::Place an unsafe trait
Consumers of `Place` would reasonably expect that the `pointer` function returns a valid pointer to memory that can actually be written to.
Thew `_raw` prefix is included because the fact that `Box`’s ownership
semantics are "dissolved" or recreated seem more important than the exact
parameter type or return type.
Introduce LinkedList::drain_filter
This introduces `LinkedList::remove_if`.
This operation embodies one of the use-cases where `LinkedList` would typically be preferred over `Vec`: random removal and retrieval.
There are a number of considerations with this:
Should there be two `remove_if` methods? One where elements are only removed, one which returns a collection of removed elements.
Should this be implemented using a draining iterator pattern that covers both cases? I suspect that would incur a bit of overhead (moving the element into the iterator, then into a new collection). But I'm not sure. Maybe that's an acceptable compromise to maximize flexibility.
I don't feel I've had enough exposure to unsafe programming in rust to be certain the implementation is correct. This relies quite heavily on moving around copies of Shared pointers to make the code reasonable. Please help me out :).
Relates to rust-lang/rfcs#2140 - drain_filter for all collections
`drain_filter` is implemented instead of `LinkedList::remove_if` based
on review feedback.
This commit removes the `rand` crate from the standard library facade as
well as the `__rand` module in the standard library. Neither of these
were used in any meaningful way in the standard library itself. The only
need for randomness in libstd is to initialize the thread-local keys of
a `HashMap`, and that unconditionally used `OsRng` defined in the
standard library anyway.
The cruft of the `rand` crate and the extra `rand` support in the
standard library makes libstd slightly more difficult to port to new
platforms, namely WebAssembly which doesn't have any randomness at all
(without interfacing with JS). The purpose of this commit is to clarify
and streamline randomness in libstd, focusing on how it's only required
in one location, hashmap seeds.
Note that the `rand` crate out of tree has almost always been a drop-in
replacement for the `rand` crate in-tree, so any usage (accidental or
purposeful) of the crate in-tree should switch to the `rand` crate on
crates.io. This then also has the further benefit of avoiding
duplication (mostly) between the two crates!
remove FIXME(#13101) since `assert_receiver_is_total_eq` stays.
remove FIXME(#19649) now that stability markers render.
remove FIXME(#13642) now the benchmarks were moved.
remove FIXME(#6220) now that floating points can be formatted.
remove FIXME(#18248) and write tests for `Rc<str>` and `Rc<[u8]>`
remove reference to irelevent issues in FIXME(#1697, #2178...)
update FIXME(#5516) to point to getopts issue 7
update FIXME(#7771) to point to RFC 628
update FIXME(#19839) to point to issue 26925
