Add suggestions to deprecation lints
Clippy used to do this suggestion, but the clippy lints happen after the deprecation lints so we ended up never seeing the structured suggestions.
Use LLVM intrinsics for saturating add/sub
Use the `[su](add|sub).sat` LLVM intrinsics, if we're compiling against LLVM 8, as they should optimize and codegen better than IR based on `[su](add|sub).with.overlow`.
For the fallback for LLVM < 8 I'm using the same expansion that target lowering in LLVM uses, which is not the same as Rust currently uses (in particular due to the use of selects rather than branches).
Fixes#55286.
Fixes#52203.
Fixes#44500.
r? @nagisa
Mark str::trim.* functions as #[must_use].
The functions return a reference to a new object and do not modify in-place
as the following code shows:
````
let s = String::from(" hello ");
s.trim();
assert_eq!(s, " hello ");
````
The new reference should be bound to a variable as now indicated by #[must_use].
Kill remaining uses of mem::uninitialized in libcore, liballoc
Kill remaining uses of mem::uninitialized in libcore and liballoc, and enable a lint that will warn when uses are added again in the future.
To avoid casting raw pointers around (which is always very dangerous because it is not typechecked at all -- it doesn't even get the "same size" sanity check that `transmute` gets), I also added two new functions to `MaybeUninit`:
```rust
/// Get a pointer to the first contained values.
pub fn first_ptr(this: &[MaybeUninit<T>]) -> *const T {
this as *const [MaybeUninit<T>] as *const T
}
/// Get a mutable pointer to the first contained values.
pub fn first_mut_ptr(this: &mut [MaybeUninit<T>]) -> *mut T {
this as *mut [MaybeUninit<T>] as *mut T
}
```
I changed some of the existing code to use array-of-`MaybeUninit` instead of `MaybeUninit`-of-array, successfully removing raw pointer casts there as well.
Use pinning for generators to make trait safe
I'm unsure whether there needs to be any changes to the actual generator transform. Tests are passing so the fact that `Pin<&mut T>` is fundamentally the same as `&mut T` seems to allow it to still work, but maybe there's something subtle here that could go wrong.
This is specified in [RFC 2349 § Immovable generators](https://github.com/rust-lang/rfcs/blob/master/text/2349-pin.md#immovable-generators) (although, since that RFC it has become safe to create an immovable generator, and instead it's unsafe to resume any generator; with these changes both are now safe and instead the unsafety is moved to creating a `Pin<&mut [static generator]>` which there are safe APIs for).
CC #43122
Refactor core::iter module
A while back, I refactored `core::ops` in #42523 because the module had become a giant mess and was difficult to modify. Now, I'm doing the same with the `core::iter` module.
Like the `core::ops` refactor, things have been split up into multiple commits to make rebasing easier, and so that you can follow changes. Although the diffs are hard to decipher, the only actual code changes I've made in the first few commits are to modify exports and imports. I save all of the actual code refactoring, e.g. modifying what methods are called, for the end.
This commit stabilizes the `Atomic{I,U}{8,16,32,64}` APIs in the
`std::sync::atomic` and `core::sync::atomic` modules. Proposed in #56753
and tracked in #32976 this feature has been unstable for quite some time
and is hopefully ready to go over the finish line now!
The API is being stabilized as-is. The API of `AtomicU8` and friends
mirrors that of `AtomicUsize`. A list of changes made here are:
* A portability documentation section has been added to describe the
current state of affairs.
* Emulation of smaller-size atomics with larger-size atomics has been
documented.
* As an added bonus, `ATOMIC_*_INIT` is now scheduled for deprecation
across the board in 1.34.0 now that `const` functions can be invoked
in statics.
Note that the 128-bit atomic types are omitted from this stabilization
explicitly. They have far less platform support than the other atomic
types, and will likely require further discussion about their best
location.
Closes#32976Closes#56753
Stabilize no_panic_pow
This would close#48320.
I'm not sure if I've done this right, I've just changed attribute name to stable and set `since` to two minor versions above current stable since that seemed like what others were doing.
