Update books
## nomicon
3 commits in f6d6126fc96ecf4a7f7d22da330df9506293b0d0..11f1165e8a2f5840467e748c8108dc53c948ee9a
2022-02-26 02:21:21 +0900 to 2022-03-19 16:02:00 -0400
- Make the Vec impl be slightly more careful with ZSTs and alignment.
- implement `IntoIterator` for `Vec` (rust-lang/nomicon#337)
- Add an explanation shared to exclusive transmute (rust-lang/nomicon#344)
## reference
2 commits in 0a2fe6651fbccc6416c5110fdf5b93fb3cb29247..c97d14fa6fed0baa9255432b8a93cb70614f80e3
2022-03-15 09:32:25 -0700 to 2022-03-19 18:18:10 -0700
- Fixed inconsistency in the usage of semicolon at end of scopes (rust-lang/reference#1182)
- Document ADX `target_feature` (rust-lang/reference#1172)
## book
23 commits in 036e88a4f135365de85358febe5324976a56030a..ea90bbaf53ba64ef4e2da9ac2352b298aec6bec8
2022-03-04 21:53:33 -0500 to 2022-03-28 21:59:34 -0400
- Fix nostarch snapshot
- Snapshot of chapter 7 for nostarch
- Add a forward reference to chapter 14, another example of pub use
- Clarify pub use example. Fixesrust-lang/book#2716.
- Fancy quotes
- Fix incorrectly worded sentence. Fixesrust-lang/book#3086.
- Reword description of how a listing came to be
- Call out binary+library crate practices
- Define binary and library crates more explicitly
- Clarify when a path is a crate name and when it should be literal crate
- Make it clearer the outer `mod` doesn't move to the file
- Don't wrap this example in main when copying. Fixesrust-lang/book#2930.
- Try to make clearer that `mod` is not an `import`
- Mention mod.rs file naming scheme
- Explain why submodule subdirectories are needed more
- Rename a separate example of serve_order to deliver_order
- Show an example that `use` only applies in its own scope
- quick modules guide
- Tweak a snippet of ch18-03
- Propagating edits to chapter 10 back
- Responses to nostarch questions of chapter 10
- Update src/ch04-01-what-is-ownership.md
- Add Danish translation link. Connects to rust-lang/book#3079.
## rust-by-example
2 commits in d504324f1e7dc7edb918ac39baae69f1f1513b8e..ec954f35eedf592cd173b21c05a7f80a65b61d8a
2022-03-07 09:26:32 -0300 to 2022-03-22 11:09:06 -0300
- PathBuf details and example (rust-lang/rust-by-example#1519)
- Move allow dead code attribute and add comment (rust-lang/rust-by-example#1518)
## rustc-dev-guide
1 commits in 0e4b961a9c708647bca231430ce1b199993e0196..155126b1d2e2cb01ddb1d7ba9489b90d7cd173ad
2022-03-14 08:40:37 -0700 to 2022-03-22 14:34:21 +0100
- update section for type system constants (rust-lang/rustc-dev-guide#1329)
## embedded-book
1 commits in d5fc1bce3f8eb398f9c25f1b15e0257d7537cd41..a6de8b6e3ea5d4f0de8b7b9a7e5c1405dc2c2ddb
2022-01-24 07:13:31 +0000 to 2022-03-17 21:21:39 +0000
- Update OpenOCD install instruction for rust-embedded/book#313 (rust-embedded/book#314)
bootstrap: better error message for no_std docs
Currently if one tries to build std documentation for a no_std target, you get a confusing error message:
`error: The argument '--package [<SPEC>...]' was provided more than once, but cannot be used multiple times`
This is because [`std_cargo`](600ec28483/src/bootstrap/compile.rs (L299-L305)) has a built-in `-p alloc` argument that conflicts with the `cargo rustdoc` command used in the Std doc step.
This just adds a better error message in this scenario. It may be possible to fix this correctly, but that would likely be a bit more of an invasive change that I don't have time for right now.
Refactor set_ptr_value as with_metadata_of
Replaces `set_ptr_value` (#75091) with methods of reversed argument order:
```rust
impl<T: ?Sized> *mut T {
pub fn with_metadata_of<U: ?Sized>(self, val: *mut U) -> *mut U;
}
impl<T: ?Sized> *const T {
pub fn with_metadata_of<U: ?Sized>(self, val: *const U) -> *const U;
}
```
By reversing the arguments we achieve several clarifications:
- The function closely resembles `cast` with an argument to
initialize the metadata. This is easier to teach and answers a long
outstanding question that had restricted cast to `Sized` pointee
targets. See multiples reviews of
<https://github.com/rust-lang/rust/pull/47631>
- The 'object identity', in the form of provenance, is now preserved
from the receiver argument to the result. This helps explain the method as
a builder-style, instead of some kind of setter that would modify
something in-place. Ensuring that the result has the identity of the
`self` argument is also beneficial for an intuition of effects.
- An outstanding concern, 'Correct argument type', is avoided by not
committing to any specific argument type. This is consistent with cast
which does not require its receiver to be a 'raw address'.
Hopefully the usage examples in `sync/rc.rs` serve as sufficient examples of the style to convince the reader of the readability improvements of this style, when compared to the previous order of arguments.
I want to take the opportunity to motivate inclusion of this method _separate_ from metadata API, separate from `feature(ptr_metadata)`. It does _not_ involve the `Pointee` trait in any form. This may be regarded as a very, very light form that does not commit to any details of the pointee trait, or its associated metadata. There are several use cases for which this is already sufficient and no further inspection of metadata is necessary.
- Storing the coercion of `*mut T` into `*mut dyn Trait` as a way to dynamically cast some an arbitrary instance of the same type to a dyn trait instance. In particular, one can have a field of type `Option<*mut dyn io::Seek>` to memorize if a particular writer is seekable. Then a method `fn(self: &T) -> Option<&dyn Seek>` can be provided, which does _not_ involve the static trait bound `T: Seek`. This makes it possible to create an API that is capable of utilizing seekable streams and non-seekable streams (instead of a possible less efficient manner such as more buffering) through the same entry-point.
- Enabling more generic forms of unsizing for no-`std` smart pointers. Using the stable APIs only few concrete cases are available. One can unsize arrays to `[T]` by `ptr::slice_from_raw_parts` but unsizing a custom smart pointer to, e.g., `dyn Iterator`, `dyn Future`, `dyn Debug`, can't easily be done generically. Exposing `with_metadata_of` would allow smart pointers to offer their own `unsafe` escape hatch with similar parameters where the caller provides the unsized metadata. This is particularly interesting for embedded where `dyn`-trait usage can drastically reduce code size.
Inline u8::is_utf8_char_boundary
Since Rust beta, Rust is incapable of inlining this function in the following example function.
```rust
pub fn safe_substr_to(s: &str, mut length: usize) -> &str {
loop {
if let Some(s) = s.get(..length) {
return s;
}
length -= 1;
}
}
```
When compiled with beta or nightly compiler on Godbolt with `-C opt-level=3` flag it prints the following assembly.
```asm
example::safe_substr_to:
push r15
push r14
push r12
push rbx
push rax
mov r14, rdi
test rdx, rdx
je .LBB0_8
mov rbx, rdx
mov r15, rsi
mov r12, qword ptr [rip + core::num::<impl u8>::is_utf8_char_boundary@GOTPCREL]
jmp .LBB0_4
.LBB0_2:
je .LBB0_9
.LBB0_3:
add rbx, -1
je .LBB0_8
.LBB0_4:
cmp rbx, r15
jae .LBB0_2
movzx edi, byte ptr [r14 + rbx]
call r12
test al, al
je .LBB0_3
mov r15, rbx
jmp .LBB0_9
.LBB0_8:
xor r15d, r15d
.LBB0_9:
mov rax, r14
mov rdx, r15
add rsp, 8
pop rbx
pop r12
pop r14
pop r15
ret
```
`qword ptr [rip + core::num::<impl u8>::is_utf8_char_boundary@GOTPCREL]` is not inlined. `-C remark=all` outputs the following message:
```
note: /rustc/7bccde19767082c7865a12902fa614ed4f8fed73/library/core/src/str/mod.rs:214:25: inline: _ZN4core3num20_$LT$impl$u20$u8$GT$21is_utf8_char_boundary17hace9f12f5ba07a7fE will not be inlined into _ZN4core3str21_$LT$impl$u20$str$GT$16is_char_boundary17hf2587e9a6b8c5e43E because its definition is unavailable
```
Stable compiler outputs more reasonable code:
```asm
example::safe_substr_to:
mov rcx, rdx
mov rax, rdi
test rdx, rdx
je .LBB0_9
mov rdx, rsi
jmp .LBB0_4
.LBB0_2:
cmp rdx, rcx
je .LBB0_7
.LBB0_3:
add rcx, -1
je .LBB0_9
.LBB0_4:
cmp rcx, rdx
jae .LBB0_2
cmp byte ptr [rax + rcx], -64
jl .LBB0_3
mov rdx, rcx
.LBB0_7:
ret
.LBB0_9:
xor edx, edx
ret
```
Link to std::io's platform-specific behavior disclaimer
This PR adds some links in standard library documentation to point to https://doc.rust-lang.org/std/io/index.html#platform-specific-behavior.
> ### Platform-specific behavior
>
> Many I/O functions throughout the standard library are documented to indicate what various library or syscalls they are delegated to. This is done to help applications both understand what’s happening under the hood as well as investigate any possibly unclear semantics. Note, however, that this is informative, not a binding contract. The implementation of many of these functions are subject to change over time and may call fewer or more syscalls/library functions.
Many of the `std::fs` APIs already link to this disclaimer when discussing system calls.
Fix yet another Box<T, A> ICE
Fixes#95036.
This widens the special case from #94414 to make sure that boxes with a custom allocator are never directly dereferenced.
parallel_compiler: hide dependencies behind feature
Separate dependencies for `parallel_compiler` feature, so they will not be compiled if feature not selected, reducing number of compiled crates from 238 to 224.
Rollup of 6 pull requests
Successful merges:
- #95301 (Remove `Nonterminal::NtTT`.)
- #95314 (Tell users that `||` operators are not currently supported in let chain expressions)
- #95350 (resolve: Simplify some diagnostic code to avoid an ICE)
- #95370 ([bootstrap] Don't print `Suite not skipped` unless `--verbose` is set)
- #95390 (Ignore doc comments in a declarative macro matcher.)
- #95401 (Remove duplicated and unused test files)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Ignore doc comments in a declarative macro matcher.
Fixes#95267. Reverts to the old behaviour before #95159 introduced a
regression.
r? `@petrochenkov`
