This commit makes two main changes.
1. It switches the spsc_queue node caching strategy from keeping a shared
counter of the number of nodes in the cache to keeping a consumer only counter
of the number of node eligible to be cached.
2. It separate the consumer and producers fields of spsc_queue and stream into
a producer cache line and consumer cache line.
The innermost type is not [u8] on all platforms but is assumed to have
the same memory layout as [u8] since this conversion was done via
mem::transmute before.
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
docs improvement std::sync::{PoisonError, TryLockError}
Addresses the `PoisonError` and `TryLockError` parts of #29377.
Adds examples and links.
r? @steveklabnik
Add blanket TryFrom impl when From is implemented.
Adds `impl<T, U> TryFrom<T> for U where U: From<T>`.
Removes `impl<'a, T> TryFrom<&'a str> for T where T: FromStr` (originally added in #40281) due to overlapping impls caused by the new blanket impl. This removal is to be discussed further on the tracking issue for TryFrom.
Refs #33417.
/cc @sfackler, @scottmcm (thank you for the help!), and @aturon
The local address's port is not 8080 in this example, that's the remote peer address port. On my machine, the local address is different every time, so I've changed `assert_eq` to only test the IP address
Allow replacing HashMap entries
This is an obvious API hole. At the moment the only way to retrieve an entry from a `HashMap` is to get an entry to it, remove it, and then insert a new entry. This PR allows entries to be replaced.
On Windows with the NTFS filesystem, `fs::copy` would return the sum of the
lengths of all streams, which can be different from the length reported by
`metadata` and thus confusing for users unaware of this NTFS peculiarity.
This makes `fs::copy` return the same length `metadata` reports which is the
value it used to return before PR #26751. Note that alternate streams are still
copied; their length is just not included in the returned value.
This change relies on the assumption that the stream with index 1 is always the
main stream in the `CopyFileEx` callback. I could not find any official
document confirming this but empirical testing has shown this to be true,
regardless of whether the alternate stream is created before or after the main
stream.
Resolves#44532
std::sync::RwLock docs improvement
Addresses the `RwLock` part of #29377.
r? @steveklabnik
Added examples, links to types, and a small comparison between RwLock and Mutex.
fix an incorrect assertion in the doc example for `std::io::copy`
I think this wasn't caught by CI because the `foo` wrapper function was only defined and not called. This seems to be the norm for doc examples that define a `foo` function. Is that on purpose?
Expand size_of docs
This PR does 3 things.
1. Adds a description of what pointer size means to the primitive pages for usize and isize.
2. Says the general size of things is not stable from compiler to compiler.
3. Adds a table of sizes of things that we do guarantee. As this is the first table in the libstd docs, I've included a picture of how that looks.

Retain suid/sgid/sticky bits in Metadata.permissions
Most users would expect set_permissions(Metadata.permissions()) to be
non-destructive. While we can't guarantee this, we can at least pass
the needed info to chmod.
Also update the PermissionsExt documentation to disambiguate what it
contains, and to refer to the underlying value as `st_mode` rather than
its type `mode_t`.
Closes#44147