Add documentation to more `From::from` implementations.
For users looking at documentation through IDE popups, this gives them relevant information rather than the generic trait documentation wording “Performs the conversion”. For users reading the documentation for a specific type for any reason, this informs them when the conversion may allocate or copy significant memory versus when it is always a move or cheap copy.
Notes on specific cases:
* The new documentation for `From<T> for T` explains that it is not a conversion at all.
* Also documented `impl<T, U> Into<U> for T where U: From<T>`, the other central blanket implementation of conversion.
* The new documentation for construction of maps and sets from arrays of keys mentions the handling of duplicates. Future work could be to do this for *all* code paths that convert an iterable to a map or set.
* I did not add documentation to conversions of a specific error type to a more general error type.
* I did not add documentation to unstable code.
This change was prepared by searching for the text "From<... for" and so may have missed some cases that for whatever reason did not match. I also looked for `Into` impls but did not find any worth documenting by the above criteria.
Destabilize cfg(target_has_atomic_load_store = ...)
This was not intended to be stabilized yet.
This keeps the cfg_target_has_atomic feature gate name since compiler-builtins otherwise depends on it and I'd rather not try to manage a bump across a crates.io published repository given the time-sensitivity here (we need to land this quickly to avoid a beta backport).
Closes https://github.com/rust-lang/rust/issues/32976
r? `@Amanieu`
Maintain broken symlink behaviour for the Windows exe resolver
When the resolver was updated to remove the current directory from the search path (see #87704), care was take to avoid unintentional changes that hadn't been discussed. However, I missed the broken symlink behaviour. This PR fixes that.
**Edit** This turned out to be more important than I first realised. There are some types of application stubs that will redirect to the actual process when run using `CreateProcessW`, but due to the way they're implemented they cannot be opened normally using a `File::open` that follows reparse points. So this doesn't work with our current `exists` and `try_exists` methods.
Fixes#91177
Update books
## nomicon
3 commits in 9493715a6280a1f74be759c7e1ef9999b5d13e6f..90993eeac93dbf9388992de92965f99cf6f29a03
2022-01-27 19:00:32 -0800 to 2022-02-13 12:44:12 +0900
- Fix a small typo in exception-safety.md (rust-lang/nomicon#341)
- Make `Vec::new` public in vec-alloc.md (rust-lang/nomicon#336)
- Fix a syntax error in leaking.md (rust-lang/nomicon#335)
## reference
6 commits in 411c2f0d5cebf48453ae2d136ad0c5e611d39aec..70fc73a6b908e08e66aa0306856c5211312f6c05
2022-01-30 12:46:37 -0800 to 2022-02-14 19:33:01 -0800
- Document pre-Rust-2021 special case for IntoIterator method lookup (rust-lang/reference#1154)
- Mention std::is_aarch64_feature_detected (rust-lang/reference#1061)
- Fix link to the Bastion of the Turbofish (rust-lang/reference#1161)
- Improve associated constant item CTFE timing section (rust-lang/reference#1147)
- document `#![feature(const_generics_defaults)]` (rust-lang/reference#1098)
- Update patterns allowed in @ patterns (rust-lang/reference#1158)
## book
6 commits in 98904efaa4fc968db8ff59cf2744d9f7ed158166..67b768c0b660a069a45f0e5d8ae2f679df1022ab
2022-01-29 21:22:31 -0500 to 2022-02-09 21:52:41 -0500
- Snapshot of ch18 for nostarch
- Remove mention of destructuring references as that's not covered currently
- Add note that exhaustiveness checking doesn't extend to match guards
- Change match guard example to actually be unexpressable with patterns alone
- Corrected listing number from 9-10 to 9-13
- Remove duplicate paragraph after No Starch related changes
## rustc-dev-guide
3 commits in 8763adb62c712df69b1d39ea3e692b6d696cc4d9..62f58394ba7b203f55ac35ddcc4c0b79578f5706
2022-01-26 14:01:40 -0800 to 2022-02-11 08:42:50 -0500
- Correction, building stage3 compiler (rust-lang/rustc-dev-guide#1298)
- Triage some date references (rust-lang/rustc-dev-guide#1293)
- mention test folders for cfg(bootstrap) (rust-lang/rustc-dev-guide#1294)
Fix inconsistent symbol mangling with -Zverbose
Always skip arguments that are the defaults of their respective
parameters, to avoid generating inconsistent symbols for builds
with `-Zverbose` flag and without it.
Support pretty printing of invalid constants
Make it possible to pretty print invalid constants by introducing a
fallible variant of `destructure_const` and falling back to debug
formatting when it fails.
Closes#93688.
Make [u8]::cmp implementation branchless
The current implementation generates rather ugly assembly code, branching when the common parts are equal. By performing the comparison of the lengths upfront using a subtraction, the assembly gets much prettier: https://godbolt.org/z/4e5fnEKGd.
This will probably not impact speed too much, as the expensive part is in most cases the `memcmp`, but it sure looks better (I'm porting a sorting algorithm currently, and that branch just bothered me).
Resolve concern of `derive_default_enum`
This resolves the concern in favor of prohibiting multiple instances of
the attribute. This is similar to non-helper attributes as introduced in
#88681.
``@rustbot`` label +S-waiting-on-review +T-libs-api
Treat static refs as `mir::ConstantKind::Val`
With the upcoming introduction of Valtrees we want to treat more values as `mir::ConstantKind::Val` directly.
r? `@lcnr`
cc `@oli-obk`
Always skip arguments that are the defaults of their respective
parameters, to avoid generating inconsistent symbols for builds
with `-Zverbose` flag and without it.
Make it possible to pretty print invalid constants by introducing a
fallible variant of `destructure_const` and falling back to debug
formatting when it fails.
Add support for control-flow protection
This change adds a flag for configuring control-flow protection in the LLVM backend. In Clang, this flag is exposed as `-fcf-protection` with options `none|branch|return|full`. This convention is followed for `rustc`, though as a codegen option: `rustc -Z cf-protection=<none|branch|return|full>`. Tracking issue for future work is #93754.
Rework GAT `where` clause check
rework the GAT where check to use a fixed-point algorithm, and check all GATs in a trait at once
fixes#93278
r? `@jackh726`
cc `@nikomatsakis`
Rollup of 5 pull requests
Successful merges:
- #93899 (Describe VecDeque with more consistent names)
- #93949 (Add basic platform support to library/{panic_}unwind for m68k)
- #93999 (suggest using raw strings when invalid escapes appear in literals)
- #94001 (llvm: migrate to new parameter-bearing uwtable attr)
- #94014 (Move transmute_undefined_repr back to nursery)
Failed merges:
- #94020 (Support pretty printing of invalid constants)
r? `@ghost`
`@rustbot` modify labels: rollup
Move transmute_undefined_repr back to nursery
There's still open discussion if this lint is ready to be enabled by
default. We want to give us more time to figure this out and prevent
this lint from getting to stable as an enabled-by-default lint.
cc https://github.com/rust-lang/rust-clippy/pull/8432
r? `@Manishearth` `@dtolnay`
I think this is the way to go here. We can re-enable this lint with the next sync, if we should decide to do so. But I would hold of for this release.
We have until Friday (beta branching) to decide if we want to merge this.
llvm: migrate to new parameter-bearing uwtable attr
In https://reviews.llvm.org/D114543 the uwtable attribute gained a flag
so that we can ask for sync uwtables instead of async, as the former are
much cheaper. The default is async, so that's what I've done here, but I
left a TODO that we might be able to do better.
While in here I went ahead and dropped support for removing uwtable
attributes in rustc: we never did it, so I didn't write the extra C++
bridge code to make it work. Maybe I should have done the same thing
with the `sync|async` parameter but we'll see.
