branchless .filter(_).count()
I found that the branchless version is only slower if we have little to no branch misses, which usually isn't the case. I notice speedups between -5% (perfect prediction) and 60% (real world data).
Add warning for () to ! switch
With feature(never_type) enabled diverging type variables will default to `!` instead of `()`. This can cause breakages where a trait is resolved on such a type.
This PR emits a future-compatibility warning when it sees this happen.
Add peek APIs to std::net
Adds "peek" APIs to `std::net` sockets, including:
- `UdpSocket.peek()`
- `UdpSocket.peek_from()`
- `TcpStream.peek()`
These methods enable socket reads without side-effects. That is, repeated calls to `peek()` return identical data. This is accomplished by providing the POSIX flag `MSG_PEEK` to the underlying socket read operations.
This also moves the current implementation of `recv_from` out of the platform-independent `sys_common` and into respective `sys/windows` and `sys/unix` implementations. This allows for more platform-dependent implementations where necessary.
Fixes#38980
Add 128-bit atomics
This is currently only supported on AArch64 since that is the only target which unconditionally supports 128-bit atomic operations.
cc #35118
Support unprivileged symlink creation in Windows
Symlink creation on Windows has in the past basically required admin; it’s being opened up a bit in the Creators Update, so that at least people who have put their computers into Developer Mode will be able to create symlinks without special privileges. (It’s unclear from what Microsoft has said whether Developer Mode will be required in the final Creators Update release, but sadly I expect it still will be, so this *still* won’t be as helpful as I’d like.)
Because of compatibility concerns, they’ve hidden this new functionality behind a new flag in the CreateSymbolicLink dwFlags: `SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE`. So we add this flag in order to join the party.
Sources:
- https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/ is the official announcement (search for CreateSymbolicLink)
- https://news.ycombinator.com/item?id=13096354 on why the new flag.
Expand documentation of process::exit and exec
Show a conventional way to use process::exit when destructors are considered important and also
mention that the same caveats wrt destructors apply to exec as well.
rustdoc: fix doctests with non-feature crate attrs
Fixes#38129.
The book says that any top-level crate attributes at the beginning of a doctest are moved outside the generated `fn main`, but it was only checking for `#![feature`, not `#![`.
These attributes previously caused warnings but were then ignored, so in theory this could change the behavior of doctests in the wild.
Implement kind="static-nobundle" (RFC 1717)
This implements the "static-nobundle" library kind (last item from #37403).
Rustc handles "static-nobundle" libs very similarly to dylibs, except that on Windows, uses of their symbols do not get marked with "dllimport". Which is the whole point of this feature.
These methods enable socket reads without side-effects. That is,
repeated calls to peek() return identical data. This is accomplished
by providing the POSIX flag MSG_PEEK to the underlying socket read
operations.
This also moves the current implementation of recv_from out of the
platform-independent sys_common and into respective sys/windows and
sys/unix implementations. This allows for more platform-dependent
implementations.
Previously, the note/message for the source of a lint being the command
line unconditionally named the individual lint, even if the actual
command specified a lint group (e.g., `-D warnings`); here, we take note
of the actual command options so we can be more specific.
This remains in the matter of #36846.
Warning or error messages set via a lint group attribute
(e.g. `#[deny(warnings)]`) should still make it clear which individual
lint (by name) was triggered, similarly to how we include "on by
default" language for default lints. This—and, while we're here, the
existing "on by default" language—can be tucked into a note rather than
cluttering the main error message. This occasions the slightest of
refactorings (we now have to get the diagnostic-builder with the main
message first, before matching on the lint source).
This is in the matter of #36846.
rewrite the predecessors code to create a reduced graph
The old code created a flat listing of "HIR -> WorkProduct" edges.
While perfectly general, this could lead to a lot of repetition if the
same HIR nodes affect many work-products. This is set to be a problem
when we start to skip typeck, since we will be adding a lot more
"work-product"-like nodes.
The newer code uses an alternative strategy: it "reduces" the graph
instead. Basically we walk the dep-graph and convert it to a DAG, where
we only keep intermediate nodes if they are used by multiple
work-products.
This DAG does not contain the same set of nodes as the original graph,
but it is guaranteed that (a) every output node is included in the graph
and (b) the set of input nodes that can reach each output node is
unchanged.
(Input nodes are basically HIR nodes and foreign metadata; output nodes
are nodes that have assocaited state which we will persist to disk in
some way. These are assumed to be disjoint sets.)
r? @michaelwoerister
Fixes#39494
Miscellaneous refactors around how lints and typeck interact
This is preparation for making incr. comp. skip typeck. The main gist of is trying to rationalize the outputs from typeck that are not part of tables:
- one bit of output is the `used_trait_imports` set, which becomes something we track for dependencies
- the other big of output are various lints; we used to store these into a table on sess, but this work stores them into the`TypeckTables`, and then makes the lint pass consult that
- I think it probably makes sense to handle errors similarly, eventually, but that's not necessary now
r? @eddyb
Fixes#39495
std: Add ToString trait specialization for Cow<'a, str> and String
There is a specialized version of ToString for str type in std. I think there are other types can also benefit from specialization. `Cow` and `String` are the most obvious one.
r? @bluss
Bump version, upgrade bootstrap
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
Use `String::with_capacity` in `format!`
Add an `Arguments::estimated_capacity` to estimate the length of formatted text and use it in `std::fmt::format` as the initial capacity of the buffer.
The capacity is calculated based on the literal parts of format string, see the details in the implementation.
Some benches:
```rust
empty: format!("{}", black_box(""))
literal: format!("Literal")
long: format!("Hello Hello Hello Hello, {}!", black_box("world"))
long_rev: format!("{}, hello hello hello hello!", black_box("world"))
long_rev_2: format!("{}{}, hello hello hello hello!", 1, black_box("world"))
short: format!("Hello, {}!", black_box("world"))
short_rev: format!("{}, hello!", black_box("world"))
short_rev_2: format!("{}{}, hello!", 1, black_box("world"))
surround: format!("aaaaa{}ccccc{}eeeee", black_box("bbbbb"), black_box("eeeee"))
two_spaced: format!("{} {}", black_box("bbbbb"), black_box("eeeee"))
worst_case: format!("{} a long piece...", black_box("and even longer argument. not sure why it has to be so long"))
```
```
empty 25 28 3 12.00%
literal 35 29 -6 -17.14%
long 80 46 -34 -42.50%
long_rev 79 45 -34 -43.04%
long_rev_2 111 66 -45 -40.54%
short 73 46 -27 -36.99%
short_rev 74 76 2 2.70%
short_rev_2 107 108 1 0.93%
surround 142 65 -77 -54.23%
two_spaced 111 115 4 3.60%
worst_case 89 101 12 13.48%
```
