This allows lints and other diagnostics to refer to items
by a unique ID instead of relying on whacky path
resolution schemes that may break when items are
relocated.
This prevents uninhabited fields from "infecting" the abi and
largest_niche of the generator layout.
This fixes a latent bug, where an uninhabited field could be promoted to
the generator prefix and cause the entire generator to become
uninhabited.
use visitor for #[structural_match] check
This changes the code so that we recur down the structure of a type of a const (rather than just inspecting at a shallow one or two levels) when we are looking to see if it has an ADT that did not derive `PartialEq` and `Eq`.
Fix#61188Fix#62307
Cc #62336
This lets you write methods using `self: Rc<Self>`, `self: Arc<Self>`, `self: Pin<&mut Self>`, `self: Pin<Box<Self>`, and other combinations involving `Pin` and another stdlib receiver type, without needing the `arbitrary_self_types`. Other user-created receiver types can be used, but they still require the feature flag to use.
This is implemented by introducing a new trait, `Receiver`, which the method receiver's type must implement if the `arbitrary_self_types` feature is not enabled. To keep composed receiver types such as `&Arc<Self>` unstable, the receiver type is also required to implement `Deref<Target=Self>` when the feature flag is not enabled.
This lets you use `self: Rc<Self>` and `self: Arc<Self>` in stable Rust, which was not allowed previously. It was agreed that they would be stabilized in #55786. `self: Pin<&Self>` and other pinned receiver types do not require the `arbitrary_self_types` feature, but they cannot be used on stable because `Pin` still requires the `pin` feature.
Fix tracking issue numbers for some unstable features
And also remove deprecated unstable `#[panic_implementation]` attribute that was superseded by stable `#[panic_handler]` and doesn't have an open tracking issue.
Rename `CoerceSized` to `DispatchFromDyn`, and reverse the direction so that, for example, you write
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const U> for *const T {}
```
instead of
```
impl<T: Unsize<U>, U> DispatchFromDyn<*const T> for *const U {}
```
this way the trait is really just a subset of `CoerceUnsized`.
The checks in object_safety.rs are updated for the new trait, and some documentation and method names in there are updated for the new trait name — e.g. `receiver_is_coercible` is now called `receiver_is_dispatchable`. Since the trait now works in the opposite direction, some code had to updated here for that too.
I did not update the error messages for invalid `CoerceSized` (now `DispatchFromDyn`) implementations, except to find/replace `CoerceSized` with `DispatchFromDyn`. Will ask for suggestions in the PR thread.
This trait is more-or-less the reverse of CoerceUnsized, and will be
used for object-safety checks. Receiver types like `Rc` will have to
implement `CoerceSized` so that methods that use `Rc<Self>` as the
receiver will be considered object-safe.
This commit extends the existing lang items functionality to assert
that the `#[lang_item]` attribute is only found on the appropriate item
for any given lang item. That is, language items representing traits
must only ever have their corresponding attribute placed on a trait, for
example.
This commit introduces language items for `Arc` and `Rc` so that types
can later be checked to be `Arc` or `Rc` in the NLL borrow checker. The
`lang` attribute is currently limited to `stage1` as it requires a
compiler built with knowledge of the expected language items.
This to-be-stable attribute is equivalent to `#[lang = "oom"]`.
It is required when using the alloc crate without the std crate.
It is called by `handle_alloc_error`, which is in turned called
by "infallible" allocations APIs such as `Vec::push`.
This is necessary if we want to implement `[T]::align_to` and is more
useful in general.
This implementation effort has begun during the All Hands and represents
a month of my futile efforts to do any sort of maths. Luckily, I
found the very very nice Chris McDonald (cjm) on IRC who figured out the
core formulas for me! All the thanks for existence of this PR go to
them!
Anyway… Those formulas were mangled by yours truly into the arcane forms
you see here to squeeze out the best assembly possible on most of the
modern architectures (x86 and ARM were evaluated in practice). I mean,
just look at it: *one actual* modulo operation and everything else is
just the cheap single cycle ops! Admitedly, the naive solution might be
faster in some common scenarios, but this code absolutely butchers the
naive solution on the worst case scenario.
Alas, the result of this arcane magic also means that the code pretty
heavily relies on the preconditions holding true and breaking those
preconditions will unleash the UB-est of all UBs! So don’t.
… previously in the unstable core::num::Float trait.
Per https://github.com/rust-lang/rust/issues/32110#issuecomment-379503183,
the `abs`, `signum`, and `powi` methods are *not* included for now
since they rely on LLVM intrinsics and we haven’t determined yet whether
those instrinsics lower to calls to libm functions on any platform.
