Commit Graph

7555 Commits

Author SHA1 Message Date
bors
1e6fe5855a Auto merge of #94079 - petrochenkov:cstr, r=joshtriplett
library: Move `CStr` to libcore, and `CString` to liballoc

Closes https://github.com/rust-lang/rust/issues/46736

Interesting points:
- Stability:
    - To make `CStr(ing)` from libcore/liballoc unusable without enabling features I had to make these structures unstable, and reexport them from libstd using stable type aliases instead of `pub use` reexports. (Because stability of `use` items is not checked.)
- Relying on target ABI in libcore is ok:
    - https://github.com/rust-lang/rust/pull/94079#issuecomment-1044263371
- `trait CStrExt` (UPDATE: used only in `cfg(bootstrap)` mode, otherwise lang items are used instead)
    - https://github.com/rust-lang/rust/pull/94079#issuecomment-1047863450
- `strlen`
    - https://github.com/rust-lang/rust/pull/94079#issuecomment-1047863450

Otherwise it's just a code move + some minor hackery usual for liballoc in `cfg(test)` mode.
2022-04-15 15:47:17 +00:00
Eduardo Sánchez Muñoz
93ae6f80e3 Make some usize-typed masks definition agnostic to the size of usize
Some masks where defined as
```rust
const NONASCII_MASK: usize = 0x80808080_80808080u64 as usize;
```
where it was assumed that `usize` is never wider than 64, which is currently true.

To make those constants valid in a hypothetical 128-bit target, these constants have been redefined in an `usize`-width-agnostic way
```rust
const NONASCII_MASK: usize = usize::from_ne_bytes([0x80; size_of::<usize>()]);
```

There are already some cases where Rust anticipates the possibility of supporting 128-bit targets, such as not implementing `From<usize>` for `u64`.
2022-04-15 17:04:59 +02:00
bors
69a5ae35fe Auto merge of #95841 - ChrisDenton:pipe-server, r=m-ou-se
Windows: Use a pipe relay for chaining pipes

Fixes #95759

This fixes the issue by chaining pipes synchronously and manually pumping messages between them. It's not ideal but it has the advantage of not costing anything if pipes are not chained ("don't pay for what you don't use") and it also avoids breaking existing code that rely on our end of the pipe being asynchronous (which includes rustc's own testing framework).

Libraries can avoid needing this by using their own pipes to chain commands.
2022-04-15 13:19:25 +00:00
Keita Nonaka
3f46ba6028 chore: formatting 2022-04-15 01:30:05 -07:00
Keita Nonaka
3f2f4a35ed test: add try_insert() test cases for BTreeSet 2022-04-15 01:12:00 -07:00
Keita Nonaka
e1626020d3 test: add get_key_value() test cases for BTreeSet 2022-04-15 00:04:03 -07:00
Keita Nonaka
4117e8c2d3 test: add pop_first() pop_last() test cases for BTreeSet 2022-04-14 23:40:05 -07:00
Vadim Petrochenkov
6eaec56ef7 library: Remove definitions and reexports of strlen from libstd 2022-04-14 21:57:01 +03:00
Vadim Petrochenkov
afa2e6f2ff Fix targets not supporting target_has_atomic = "ptr" 2022-04-14 21:53:11 +03:00
Vadim Petrochenkov
7f3cc2fbbf library: Use type aliases to make CStr(ing) in libcore/liballoc unstable 2022-04-14 21:53:11 +03:00
Vadim Petrochenkov
5bee741a08 library: Move CStr to libcore, and CString to liballoc 2022-04-14 21:53:11 +03:00
Eduardo Sánchez Muñoz
2a91eeac1a Implement core::ptr::Unique on top of NonNull
Removes the use `rustc_layout_scalar_valid_range_start` and some `unsafe` blocks.
2022-04-14 19:35:40 +02:00
Mara Bos
7a35c0f52d Use u32 instead of i32 for futexes. 2022-04-14 11:44:12 +02:00
Boyd Kane
d73e32867f
Remove trailing whitespace
Co-authored-by: Mara Bos <m-ou.se@m-ou.se>
2022-04-14 11:19:49 +02:00
Boyd Kane
f6d957701f
docs: add link from zip to unzip
The docs for `Iterator::unzip` explain that it is kind of an inverse operation to `Iterator::zip` and guide the reader to the `zip` docs, but the `zip` docs don't let the user know that they can undo the `zip` operation with `unzip`. This change modifies the docs to help the user find `unzip`.
2022-04-14 09:51:47 +02:00
Keita Nonaka
50c339e8f5 test: add remove() test cases for BTreeSet 2022-04-13 22:19:08 -07:00
Keita Nonaka
21d3f8444a test: add is_superset test cases for BTreeSet 2022-04-13 22:09:03 -07:00
bors
dc4bfcbdff Auto merge of #95958 - jhpratt:bump-stdarch, r=Dylan-DPC
Update stdarch

library/stdarch bcbe0106...d215afe9 (7):
  - Add the rdm target feature to the sqrdmlsh intrinsic. (rust-lang/stdarch#1285)
  - Remove use of `#[rustc_deprecated]`
  - Remove feature gates for stabilized features
  - Change remaining _undefined_ functions to zero-init
  - Use SPDX license format and update packed_simd crate link (rust-lang/stdarch#1297)
  - Fix broken links (rust-lang/stdarch#1294)
  - Import the asm macro in std_detect (rust-lang/stdarch#1290)
2022-04-13 18:44:35 +00:00
bors
0d13f6afeb Auto merge of #96015 - Dylan-DPC:rollup-vhdprid, r=Dylan-DPC
Rollup of 6 pull requests

Successful merges:

 - #93217 (Improve Rustdoc UI for scraped examples with multiline arguments, fix overflow in line numbers)
 - #95885 (Improve error message in case of missing checksum)
 - #95962 (Document that DirEntry holds the directory open)
 - #95991 (fix: wrong trait import suggestion for T:)
 - #96005 (Add missing article to fix "few" to "a few".)
 - #96006 (Add a missing article)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
2022-04-13 16:04:06 +00:00
Dylan DPC
e95f2db98f
Rollup merge of #96006 - hkBst:patch-2, r=Dylan-DPC
Add a missing article

Add a missing article
2022-04-13 17:35:37 +02:00
Dylan DPC
e8050c0b0a
Rollup merge of #96005 - hkBst:patch-1, r=Dylan-DPC
Add missing article to fix "few" to "a few".

Add missing article to fix "few" (not many) to "a few" (some).
2022-04-13 17:35:35 +02:00
Dylan DPC
032358bd30
Rollup merge of #95962 - sourcefrog:doc-direntry, r=Dylan-DPC
Document that DirEntry holds the directory open

I had a bug where holding onto DirEntry structs caused file descriptor exhaustion, and thought it would be good to document this.
2022-04-13 17:35:33 +02:00
bors
ab33f71a8b Auto merge of #95727 - m-ou-se:futex-reentrantmutex, r=Amanieu
Replace ReentrantMutex by a futex-based one on Linux.

Tracking issue: https://github.com/rust-lang/rust/issues/93740

r? `@Amanieu`
2022-04-13 13:42:19 +00:00
Marijn Schouten
c008d45187
Add a missing article
Add a missing article
2022-04-13 13:33:09 +02:00
Marijn Schouten
212e98bc3e
Add missing article to fix "few" to "a few".
Add missing article to fix "few" (not many) to "a few" (some).
2022-04-13 13:24:28 +02:00
Nicholas Nethercote
9c59d04d55 Speed up Vec::clear().
Currently it just calls `truncate(0)`. `truncate()` is (a) not marked as
`#[inline]`, and (b) more general than needed for `clear()`.

This commit changes `clear()` to do the work itself. This modest change
was first proposed in rust-lang#74172, where the reviewer rejected it because
there was insufficient evidence that `Vec::clear()`'s performance
mattered enough to justify the change. Recent changes within rustc have
made `Vec::clear()` hot within `macro_parser.rs`, so the change is now
clearly worthwhile.

Although it doesn't show wins on CI perf runs, this seems to be because they
use PGO. But not all platforms currently use PGO. Also, local builds don't use
PGO, and `truncate` sometimes shows up in an over-represented fashion in local
profiles. So local profiling will be made easier by this change.

Note that this will also benefit `String::clear()`, because it just
calls `Vec::clear()`.

Finally, the commit removes the `vec-clear.rs` codegen test. It was
added in #52908. From before then until now, `Vec::clear()` just called
`Vec::truncate()` with a zero length. The body of Vec::truncate() has
changed a lot since then. Now that `Vec::clear()` is doing actual work
itself, and not just calling `Vec::truncate()`, it's not surprising that
its generated code includes a load and an icmp. I think it's reasonable
to remove this test.
2022-04-13 15:39:35 +10:00
Dylan DPC
633c391225
Rollup merge of #95984 - wcampbell0x2a:fix-spelling, r=thomcc
Fix spelling in docs for `can_not_overflow`

Introduced in https://github.com/rust-lang/rust/pull/95399
2022-04-13 05:54:13 +02:00
Dylan DPC
6aa875aa96
Rollup merge of #95914 - c410-f3r:meta-vars, r=petrochenkov
Implement tuples using recursion

Because it is c00l3r™, requires less repetition and can be used as a reference for external people.

This change is non-essential and I am not sure about potential performance impacts so feel free to close this PR if desired.

r? `@petrochenkov`
2022-04-12 23:16:58 +02:00
Caio
23bf977758 Implement tuples using recursion 2022-04-12 16:23:36 -03:00
wcampbell
9ea89e1d3d Fix spelling in docs for can_not_overflow 2022-04-12 13:29:56 -04:00
Ralf Jung
e886dc52ee portable-simd: use simd_arith_offset to avoid ptr-int transmutation 2022-04-12 11:09:26 -04:00
fee1-dead
1d76dd9ee7
Rollup merge of #95947 - cuviper:default-box, r=dtolnay
`impl const Default for Box<[T]>` and `Box<str>`

The unstable `const_default_impls` (#87864) already include empty `Vec<T>` and `String`. Now we extend that concept to `Box<[T]>` and `Box<str>` as well.

This obviates a hack in `rustc_ast`'s `P::<[T]>::new`.
2022-04-12 22:44:45 +10:00
fee1-dead
cdbdf1ef2e
Rollup merge of #95900 - o01eg:fix-wasm-doc, r=Mark-Simulacrum
Fix documentation for wasm32-unknown-unknown

Fixes https://github.com/rust-lang/rust/issues/76526#issuecomment-1094208720
2022-04-12 22:44:44 +10:00
Mara Bos
d4e44a6391 Add missing unsafe marker.
This is now necessary because of deny(unsafe_op_in_unsafe_fn).
2022-04-12 08:44:39 +02:00
Mara Bos
8a2c9a9615 Allow cvt_nz to be unused on some platforms. 2022-04-12 08:44:39 +02:00
Mara Bos
5b2591299a Add #[deny(unsafe_op_in_unsafe_fn)] to thread_local!(const).
This avoids 'unused unsafe' warnings when using this feature inside std.
2022-04-12 08:44:39 +02:00
Mara Bos
83e8b9e4dd Add debug asserts to futex ReentrantMutex impl. 2022-04-12 08:44:39 +02:00
Mara Bos
43651aa34f Initialize thread local with const{}. 2022-04-12 08:44:39 +02:00
Mara Bos
319a9b0f71 Move current_thread_unique_ptr to the only module that uses it. 2022-04-12 08:44:39 +02:00
Mara Bos
ebebe6f837 Make current_thread_unique_ptr work during thread destruction.
Otherwise we can't use println!() within atexit handlers etc.
2022-04-12 08:44:38 +02:00
Mara Bos
bd61bec67d Add futex-based ReentrantMutex on Linux. 2022-04-12 08:44:38 +02:00
Mara Bos
c62c8cb82d Add current_thread_unique_ptr() in std::sys_common. 2022-04-12 08:41:42 +02:00
bors
4e1927db3c Auto merge of #95399 - gilescope:plan_b, r=scottmcm
Faster parsing for lower numbers for radix up to 16 (cont.)

( Continuation of https://github.com/rust-lang/rust/pull/83371 )

With LingMan's change I think this is potentially ready.
2022-04-12 05:54:50 +00:00
Martin Pool
7cdef0876d Document that DirEntry holds the directory open 2022-04-11 19:00:29 -07:00
Jacob Pratt
2638e969c8
Bump stdarch 2022-04-11 21:40:31 -04:00
bors
36f4ded69e Auto merge of #93408 - liangyongrui:master, r=scottmcm
fix Layout struct member naming style
2022-04-12 00:18:51 +00:00
Josh Stone
a2902ebe57 impl const Default for Box<[T]> and Box<str> 2022-04-11 12:14:18 -07:00
Dylan DPC
ae6f75a0c3
Rollup merge of #95895 - CAD97:patch-2, r=Dylan-DPC
Clarify str::from_utf8_unchecked's invariants

Specifically, make it clear that it is immediately UB to pass ill-formed UTF-8 into the function. The previous wording left space to interpret that the UB only occurred when calling another function, which "assumes that `&str`s are valid UTF-8."

This does not change whether str being UTF-8 is a safety or a validity invariant. (As per previous discussion, it is a safety invariant, not a validity invariant.) It just makes it clear that valid UTF-8 is a precondition of str::from_utf8_unchecked, and that emitting an Abstract Machine fault (e.g. UB or a sanitizer error) on invalid UTF-8 is a valid thing to do.

If user code wants to create an unsafe `&str` pointing to ill-formed UTF-8, it must be done via transmutes. Also, just, don't.

Zulip discussion: https://rust-lang.zulipchat.com/#narrow/stream/136281-t-lang.2Fwg-unsafe-code-guidelines/topic/str.3A.3Afrom_utf8_unchecked.20Safety.20requirement
2022-04-11 20:00:44 +02:00
Dylan DPC
82a6463b1c
Rollup merge of #95894 - nyanpasu64:fix-pin-docs, r=Dylan-DPC
Fix formatting error in pin.rs docs

Not sure if there's more formatting issues I missed; I kinda lost interest reading midway through.
2022-04-11 20:00:43 +02:00
Dylan DPC
a15ac30162
Rollup merge of #95801 - m-ou-se:futex-rwlock, r=Amanieu
Replace RwLock by a futex based one on Linux

This replaces the pthread-based RwLock on Linux by a futex based one.

This implementation is similar to [the algorithm](https://gist.github.com/kprotty/3042436aa55620d8ebcddf2bf25668bc) suggested by `@kprotty,` but modified to prefer writers and spin before sleeping. It uses two futexes: One for the readers to wait on, and one for the writers to wait on. The readers futex contains the state of the RwLock: The number of readers, a bit indicating whether writers are waiting, and a bit indicating whether readers are waiting. The writers futex is used as a simple condition variable and its contents are meaningless; it just needs to be changed on every notification.

Using two futexes rather than one has the obvious advantage of allowing a separate queue for readers and writers, but it also means we avoid the problem a single-futex RwLock would have of making it hard for a writer to go to sleep while the number of readers is rapidly changing up and down, as the writers futex is only changed when we actually want to wake up a writer.

It always prefers writers, as we decided [here](https://github.com/rust-lang/rust/issues/93740#issuecomment-1070696128).

To be able to prefer writers, it relies on futex_wake to return the number of awoken threads to be able to handle write-unlocking while both the readers-waiting and writers-waiting bits are set. Instead of waking both and letting them race, it first wakes writers and only continues to wake the readers too if futex_wake reported there were no writers to wake up.

r? `@Amanieu`
2022-04-11 20:00:41 +02:00
O01eg
3f4bbd50fd
Fix documentation for wasm32-unknown-unknown 2022-04-11 19:16:51 +03:00
Mara Bos
8339381741 Use is_ or has_ prefix for pure -> bool functions. 2022-04-11 14:52:02 +02:00
Mara Bos
c4a4f48c52 Use compare_exchange_weak in futex rwlock implementation. 2022-04-11 14:29:32 +02:00
Mara Bos
1f2c2bb24f Add comments to futex rwlock implementation. 2022-04-11 14:27:06 +02:00
Mara Bos
7c28791565 Add doc comments to futex operations. 2022-04-11 14:26:52 +02:00
Matthias Krüger
5b8e2ea520
Rollup merge of #95917 - RalfJung:thin-box-test, r=dtolnay
thin_box test: import from std, not alloc

Importing from `alloc` makes [Miri fail](https://github.com/rust-lang/miri-test-libstd/runs/5964922742?check_suite_focus=true), probably due to the hack that we used to resolve https://github.com/rust-lang/miri-test-libstd/issues/4. There might be better ways around this, but for now this is the easiest thing to do -- no other alloc integration test is importing from `alloc::`.
2022-04-11 12:06:58 +02:00
Matthias Krüger
e25bc303f1
Rollup merge of #95743 - yaahc:binary-search-clarification, r=Mark-Simulacrum
Update binary_search example to instead redirect to partition_point

Inspired by discussion in the tracking issue for `Result::into_ok_or_err`: https://github.com/rust-lang/rust/issues/82223#issuecomment-1067098167

People are surprised by us not providing a `Result<T, T> -> T` conversion, and the main culprit for this confusion seems to be the `binary_search` API. We should instead redirect people to the equivalent API that implicitly does that `Result<T, T> -> T` conversion internally which should obviate the need for the `into_ok_or_err` function and give us time to work towards a more general solution that applies to all enums rather than just `Result` such as making or_patterns usable for situations like this via postfix `match`.

I choose to duplicate the example rather than simply moving it from `binary_search` to partition point because most of the confusion seems to arise when people are looking at `binary_search`. It makes sense to me to have the example presented immediately rather than requiring people to click through to even realize there is an example. If I had to put it in only one place I'd leave it in `binary_search` and remove it from `partition_point` but it seems pretty obviously relevant to `partition_point` so I figured the best option would be to duplicate it.
2022-04-11 12:06:52 +02:00
Giles Cope
3ee7bb19c6
better def of is signed in tests. 2022-04-11 07:37:53 +01:00
liangyongrui
03b2588837 fix Layout struct member naming style 2022-04-11 13:35:18 +08:00
Ralf Jung
dbc0afa215 thin_box test: import from std, not alloc 2022-04-10 22:59:51 -04:00
Christopher Durham
b92cd1a32c
Clarify str::from_utf8_unchecked's invariants
Specifically, make it clear that it is immediately UB to pass ill-formed UTF-8 into the function. The previous wording left space to interpret that the UB only occurred when calling another function, which "assumes that `&str`s are valid UTF-8."

This does not change whether str being UTF-8 is a safety or a validity invariant. (As per previous discussion, it is a safety invariant, not a validity invariant.) It just makes it clear that valid UTF-8 is a precondition of str::from_utf8_unchecked, and that emitting an Abstract Machine fault (e.g. UB or a sanitizer error) on invalid UTF-8 is a valid thing to do.

If user code wants to create an unsafe `&str` pointing to ill-formed UTF-8, it must be done via transmutes. Also, just, don't.
2022-04-10 15:04:57 -05:00
nyanpasu64
bb3a071df8
Fix formatting error in pin.rs docs 2022-04-10 12:41:31 -07:00
Dylan DPC
c0655dec7e
Rollup merge of #95566 - eduardosm:std_char_consts_and_methods, r=Mark-Simulacrum
Avoid duplication of doc comments in `std::char` constants and functions

For those consts and functions, only the summary is kept and a reference to the `char` associated const/method is included.

Additionaly, re-exported functions have been converted to function definitions that call the previously re-exported function. This makes it easier to add a deprecated attribute to these functions in the future.
2022-04-10 21:03:34 +02:00
Giles Cope
79e8653656
No need to use Default 2022-04-10 18:20:13 +01:00
Giles Cope
515906a669
Use Add, Sub, Mul traits instead of unsafe 2022-04-10 18:13:48 +01:00
bors
7af93292c2 Auto merge of #95621 - saethlin:remove-mpsc-transmute, r=RalfJung
Remove ptr-int transmute in std::sync::mpsc

Since https://github.com/rust-lang/rust/pull/95340 landed, Miri with `-Zmiri-check-number-validity` produces an error on the test suites of some crates which implement concurrency tools<sup>*</sup>, because it seems like such crates tend to use `std::sync::mpsc` in their tests. This fixes the problem by storing pointer bytes in a pointer.

<sup>*</sup> I have so far seen errors in the test suites of `once_cell`, `parking_lot`, and `crossbeam-utils`.
(just updating the list for fun, idk)
Also `threadpool`, `async-lock`, `futures-timer`, `fragile`, `scoped_threadpool`, `procfs`, `slog-async`, `scheduled-thread-pool`, `tokio-threadpool`, `mac`, `futures-cpupool`, `ntest`, `actix`, `zbus`, `jsonrpc-client-transports`, `fail`, `libp2p-gossipsub`, `parity-send-wrapper`, `async-broadcast,` `libp2p-relay`, `http-client`, `mockito`, `simple-mutex`, `surf`, `pollster`, and `pulse`. Then I turned the bot off.
2022-04-10 08:57:32 +00:00
Dylan DPC
7726265ae0
Rollup merge of #95831 - redzic:xor-uppercase, r=workingjubilee
Use bitwise XOR in to_ascii_uppercase

This saves an instruction compared to the previous approach, which
was to unset the fifth bit with bitwise OR.

Comparison of generated assembly on x86: https://godbolt.org/z/GdfvdGs39

This can also affect autovectorization, saving SIMD instructions as well: https://godbolt.org/z/cnPcz75T9

Not sure if `u8::to_ascii_lowercase` should also be changed, since using bitwise OR for that function does not require an extra bitwise negate since the code is setting a bit rather than unsetting a bit. `char::to_ascii_uppercase` already uses XOR, so no change seems to be required there.
2022-04-09 18:26:30 +02:00
Dylan DPC
2464ea2510
Rollup merge of #95817 - oconnor663:doc_comment2, r=yaahc
hide another #[allow] directive from a docs example

This is a repeat for Rc of e0e64a8930,
which cleaned up the same thing for Arc.
2022-04-09 18:26:29 +02:00
Dylan DPC
5092946041
Rollup merge of #95805 - c410-f3r:meta-vars, r=petrochenkov
Left overs of #95761

These are just nits. Feel free to close this PR if all modifications are not worth merging.

* `#![feature(decl_macro)]` is not needed anymore in `rustc_expand`
* `tuple_impls` does not require `$Tuple:ident`. I guess it is there to enhance readability?

r? ```@petrochenkov```
2022-04-09 18:26:27 +02:00
Dylan DPC
e4b4bf1535
Rollup merge of #95361 - scottmcm:valid-align, r=Mark-Simulacrum
Make non-power-of-two alignments a validity error in `Layout`

Inspired by the zulip conversation about how `Layout` should better enforce `size <= isize::MAX as usize`, this uses an N-variant enum on N-bit platforms to require at the validity level that the existing invariant of "must be a power of two" is upheld.

This was MIRI can catch it, and means there's a more-specific type for `Layout` to store than just `NonZeroUsize`.

It's left as `pub(crate)` here; a future PR could consider giving it a tracking issue for non-internal usage.
2022-04-09 18:26:25 +02:00
Dylan DPC
1ced0b61a4
Rollup merge of #94794 - mlodato517:mlodato517-clarify-string-indexing-docs, r=Mark-Simulacrum
Clarify indexing into Strings

**This Commit**
Adds some clarity around indexing into Strings.

**Why?**
I was reading through the `Range` documentation and saw an
implementation for `SliceIndex<str>`. I was surprised to see this and
went to read the [`String`][0] documentation and, to me, it seemed to
say (at least) three things:

1. you cannot index into a `String`
2. indexing into a `String` could not be constant-time
3. indexing into a `String` does not have an obvious return type

I absolutely agree with the last point but the first two seemed
contradictory to the documentation around [`SliceIndex<str>`][1]
which mention:

1. you can do substring slicing (which is probably different than
   "indexing" but, because the method is called `index` and I associate
   anything with square brackets with "indexing" it was enough to
   confuse me)
2. substring slicing is constant-time (this may be algorithmic ignorance
   on my part but if `&s[i..i+1]` is O(1) then it seems confusing that
   `&s[i]` _could not possibly_ be O(1))

So I was hoping to clarify a couple things and, hopefully, in this PR
review learn a little more about the nuances here that confused me in
the first place.

[0]: https://doc.rust-lang.org/stable/std/string/struct.String.html#utf-8
[1]: https://doc.rust-lang.org/stable/std/slice/trait.SliceIndex.html#impl-SliceIndex%3Cstr%3E
2022-04-09 18:26:25 +02:00
Mark Lodato
9cf35a6c06 Rework String UTF-8 Documentation
**This Commit**
Adds some clarity around indexing into Strings and the constraints
driving various decisions there.

**Why?**
The [`String` documentation][0] mentions how `String`s can't be indexed
but `Range` has an implementation for `SliceIndex<str>`. This can be
confusing. There are also several statements to explain the lack of
`String` indexing:

- the inability to index into a `String` is an implication of UTF-8
  encoding
- indexing into a `String` could not be constant-time with UTF-8
  encoding
- indexing into a `String` does not have an obvious return type

This last statement made sense but the first two seemed contradictory to
the documentation around [`SliceIndex<str>`][1] which mention:

- one can index into a `String` with a `Range` (also called substring
  slicing but it uses the same syntax and the method name is `index`)
- `Range` indexing into a `String` is constant-time

To resolve this seeming contradiction the documentation is reworked to
more clearly explain what factors drive the decision to disallow
indexing into a `String` with a single number.

[0]: https://doc.rust-lang.org/stable/std/string/struct.String.html#utf-8
[1]: https://doc.rust-lang.org/stable/std/slice/trait.SliceIndex.html#impl-SliceIndex%3Cstr%3E
2022-04-09 09:27:32 -04:00
Dylan DPC
af895b0715
Rollup merge of #95802 - RalfJung:unused-win, r=Dylan-DPC
fix unused constant warning on some Windows targets

When none of those `cfg_if!` apply (and on Miri), the constant remains unused.
2022-04-09 12:52:06 +02:00
Dylan DPC
e232cb42e6
Rollup merge of #95308 - bjorn3:more_stable_proc_macro, r=Mark-Simulacrum
Reduce the amount of unstable features used in libproc_macro

This makes it easier to adapt the source for stable when copying it into rust-analyzer to load rustc compiled proc macros.
2022-04-09 12:52:02 +02:00
Dylan DPC
8d7392232c
Rollup merge of #95787 - yaahc:panic-doc-update-v2, r=dtolnay
reword panic vs result section to remove recoverable vs unrecoverable framing

Based on feedback from the Error Handling FAQ: https://github.com/rust-lang/project-error-handling/issues/50#issuecomment-1090876982

r? ````@dtolnay````
2022-04-09 05:58:44 +02:00
Ben Kimock
dec73f58d8 Remove ptr-int transmute in std::sync::mpsc
Since https://github.com/rust-lang/rust/pull/95340 landed, Miri with
-Zmiri-check-number-validity produces an error on the test suites of
some crates which implement concurrency tools, because it seems like
such crates tend to use std::sync::mpsc in their tests. This fixes the
problem by storing pointer bytes in a pointer.
2022-04-08 23:28:31 -04:00
Scott McMurray
fe0c08a4f2 Make non-power-of-two alignments a validity error in Layout
Inspired by the zulip conversation about how `Layout` should better enforce `size < isize::MAX as usize`, this uses an N-variant enum on N-bit platforms to require at the validity level that the existing invariant of "must be a power of two" is upheld.

This was MIRI can catch it, and means there's a more-specific type for `Layout` to store than just `NonZeroUsize`.
2022-04-08 20:17:38 -07:00
Redzic
1e6365d075 Use bitwise XOR in to_ascii_uppercase
This saves an instruction compared to the previous approach, which
was to unset the fifth bit with bitwise OR.
2022-04-08 20:06:54 -05:00
Jack O'Connor
c1023e9e5f hide another #[allow] directive from a docs example
This is a repeat for Rc of e0e64a8930,
which cleaned up the same thing for Arc.
2022-04-08 10:29:50 -07:00
Jane Lusby
a87a0d089e Add ThinBox type for 1 stack pointer sized heap allocated trait objects
Relevant commit messages from squashed history in order:

Add initial version of ThinBox

update test to actually capture failure

swap to middle ptr impl based on matthieu-m's design

Fix stack overflow in debug impl

The previous version would take a `&ThinBox<T>` and deref it once, which
resulted in a no-op and the same type, which it would then print causing
an endless recursion. I've switched to calling `deref` by name to let
method resolution handle deref the correct number of times.

I've also updated the Drop impl for good measure since it seemed like it
could be falling prey to the same bug, and I'll be adding some tests to
verify that the drop is happening correctly.

add test to verify drop is behaving

add doc examples and remove unnecessary Pointee bounds

ThinBox: use NonNull

ThinBox: tests for size

Apply suggestions from code review

Co-authored-by: Alphyr <47725341+a1phyr@users.noreply.github.com>

use handle_alloc_error and fix drop signature

update niche and size tests

add cfg for allocating APIs

check null before calculating offset

add test for zst and trial usage

prevent optimizer induced ub in drop and cleanup metadata gathering

account for arbitrary size and alignment metadata

Thank you nika and thomcc!

Update library/alloc/src/boxed/thin.rs

Co-authored-by: Josh Triplett <josh@joshtriplett.org>

Update library/alloc/src/boxed/thin.rs

Co-authored-by: Josh Triplett <josh@joshtriplett.org>
2022-04-08 09:00:16 -07:00
Mara Bos
307aa588f4
Fix typo in futex rwlock.
Co-authored-by: Amanieu d'Antras <amanieu@gmail.com>
2022-04-08 16:07:07 +02:00
Caio
e946aa3a74 Left overs of #95761 2022-04-08 10:30:24 -03:00
Ralf Jung
9c977530b5 fix some unused constant warning on some Windows targets 2022-04-08 08:36:56 -04:00
Mara Bos
6cb463cb11 Add futex-based RwLock on Linux. 2022-04-08 13:49:18 +02:00
bors
e4f5b15b88 Auto merge of #95798 - Dylan-DPC:rollup-51hx1wl, r=Dylan-DPC
Rollup of 7 pull requests

Successful merges:

 - #95102 (Add known-bug for #95034)
 - #95579 (Add `<[[T; N]]>::flatten{_mut}`)
 - #95634 (Mailmap update)
 - #95705 (Promote x86_64-unknown-none target to Tier 2 and distribute build artifacts)
 - #95761 (Kickstart the inner usage of `macro_metavar_expr`)
 - #95782 (Windows: Increase a pipe's buffer capacity to 64kb)
 - #95791 (hide an #[allow] directive from the Arc::new_cyclic doc example)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
2022-04-08 10:41:10 +00:00
Chris Denton
90130549f4
Windows: Use a pipe relay for chaining pipes 2022-04-08 11:35:29 +01:00
Dylan DPC
7b285d09e9
Rollup merge of #95791 - oconnor663:doc_comment, r=thomcc
hide an #[allow] directive from the Arc::new_cyclic doc example

A minor docs cleanup.
2022-04-08 11:48:26 +02:00
Dylan DPC
fdfdb336e2
Rollup merge of #95782 - ChrisDenton:pipe-buffer-size, r=thomcc
Windows: Increase a pipe's buffer capacity to 64kb

This brings it inline with typical Linux defaults: https://www.man7.org/linux/man-pages/man7/pipe.7.html

> Since Linux 2.6.11, the pipe capacity is 16 pages (i.e., 65,536 bytes in a system with a page size of 4096 bytes).

This may also help with #45572 and #95759 but does not fix either issue. It simply makes them much less likely to be encountered.
2022-04-08 11:48:25 +02:00
Dylan DPC
1f80881a94
Rollup merge of #95761 - c410-f3r:meta-var-stuff, r=petrochenkov
Kickstart the inner usage of `macro_metavar_expr`

There can be more use-cases but I am out of ideas.

cc #83527
r? ``@petrochenkov``
2022-04-08 11:48:24 +02:00
Dylan DPC
d5232c6b93
Rollup merge of #95579 - Cyborus04:slice_flatten, r=scottmcm
Add `<[[T; N]]>::flatten{_mut}`

Adds `flatten` to convert `&[[T; N]]` to `&[T]` (and `flatten_mut` for `&mut [[T; N]]` to `&mut [T]`)
2022-04-08 11:48:21 +02:00
bors
1a4b9a8563 Auto merge of #95775 - RalfJung:miri-windows-compat, r=ChrisDenton
make windows compat_fn (crudely) work on Miri

With https://github.com/rust-lang/rust/pull/95469, Windows `compat_fn!` now has to be supported by Miri to even make stdout work. Unfortunately, it relies on some outside-of-Rust linker hacks (`#[link_section = ".CRT$XCU"]`) that are rather hard to make work in Miri. So I came up with this crude hack to make this stuff work in Miri regardless. It should come at no cost for regular executions, so I hope this is okay.

Cc https://github.com/rust-lang/rust/issues/95627 `@ChrisDenton`
2022-04-08 08:13:21 +00:00
Cyborus04
06788fd7a4 add <[[T; N]]>::flatten, <[[T; N]]>::flatten_mut, and Vec::<[T; N]>::into_flattened 2022-04-08 00:54:39 -04:00
Jack O'Connor
e0e64a8930 hide an #[allow] directive from the Arc::new_cyclic doc example 2022-04-07 18:00:46 -07:00
Jacob Pratt
a3dd654ae9
Add documentation 2022-04-07 20:03:24 -04:00
Jacob Pratt
abf2b4c04d
Stabilize derive_default_enum 2022-04-07 20:03:19 -04:00
Jane Lusby
aa3c141c86 reword panic vs result section to remove recoverable vs unrecoverable framing 2022-04-07 13:44:57 -07:00
Chris Denton
6a4b44426b
Windows: Increase a pipe's buffer capacity to 64kb
This brings it inline with typical Linux defaults: https://www.man7.org/linux/man-pages/man7/pipe.7.html
2022-04-07 20:34:55 +01:00
Ralf Jung
c599a4cfc3 do not round-trip function pointer through integer 2022-04-07 15:00:07 -04:00
Ralf Jung
fe85591989 make windows compat_fn (crudely) work on Miri 2022-04-07 14:07:02 -04:00
Caio
3191d27f48 Kickstart the inner usage of macro_metavar_expr 2022-04-07 08:13:41 -03:00