In particular, uses of inclusive ranges within the standard library are
still waiting. Slices and collections can be sliced with `usize` and
`Range*<usize>`, but not yet `Range*Inclusive<usize>`.
Also, we need to figure out what to do about `RangeArgument`. Currently
it has `start()` and `end()` methods which are pretty much identical to
`Range::start` and `Range::end`. For the same reason as Range itself,
these methods can't express a range such as `0...255u8` without
overflow. The easiest choice, it seems to me, is either changing the
meaning of `end()` to be inclusive, or adding a new method, say
`last()`, that is inclusive and specifying that `end()` returns `None`
in cases where it would overflow. Changing the semantics would be a
breaking change, but `RangeArgument` is unstable so maybe we should do
it anyway.
The range desugaring does not use the lang items. Hence I did not add
lang items for inclusive ranges. This cleanup commit removes the old
unused ones as well.
Whether the desugaring _should_ use lang items is another question:
see #30809. But if we decide on a strategy there we can add back these
lang items, and new ones for inclusive ranges.
For stage0 we need to keep the attributes as the lang items still exist
even if they are never used.
This is surprisingly not a breaking change. Unused #[lang] attributes do
not even trigger a lint (see #30881).
.copy_from_slice() does the same job of .clone_from_slice(), but the
former is explicitly for Copy elements and calls `memcpy` directly, and
thus is it efficient without optimization too.
Tracking issue: #31756
RFC: rust-lang/rfcs#1467
I've made these unstable for now. Should they be stabilized straight away since we've had plenty of experience with people using the unstable intrinsics?
fmt: Make sure write_fmt's implementation can use write_char
It looks like the Adapter inside write_fmt was never updated to forward
the write_char method.
`wrapping_shl` and `wrapping_shr` are easy to mistake for rotations, when in fact they work somewhat differently. The documentation currently available is a little sparse and easy to misinterpret, so I've added a warning to anyone who bumps into them that the equivalent rotate methods may actually be what they're looking for.
If it's deemed useful to add a symmetrical mention to the documentation for the `rotate_left` and `rotate_right` methods, I can certainly have a go at that, but my gut feeling is that people likely to want a rotate will already know about the wrapping-arithmetic methods, for example from writing CPU simulators.
This allows printing pointers to unsized types with the {:p} formatting
directive. The following impls are extended to unsized types:
- impl<'a, T: ?Sized> Pointer for &'a T
- impl<'a, T: ?Sized> Pointer for &'a mut T
- impl<T: ?Sized> Pointer for *const T
- impl<T: ?Sized> Pointer for *mut T
- impl<T: ?Sized> fmt::Pointer for Box<T>
- impl<T: ?Sized> fmt::Pointer for Rc<T>
- impl<T: ?Sized> fmt::Pointer for Arc<T>
This commit does two things:
* Re-works the module-level documentation.
* Cleaning up wording and adding links to where error types are used.
Part of #29364
This commit does two things:
* Re-works the module-level documentation.
* Cleaning up wording and adding links to where error types are used.
Part of #29364
Since a lexicographic ordering of a struct could vary based on which struct members are compared first, I ended up doing some testing to ensure that the behavior when deriving these traits was what I expected (ordered based on the top to bottom order of declaration of the members). I wanted to add this little bit of documentation to potentially save someone else the same effort. That is, assuming that my testing correctly reflects the intended behavior of the compiler.
r? @steveklabnik
This allows printing pointers to unsized types with the {:p} formatting
directive. The following impls are extended to unsized types:
- impl<'a, T: ?Sized> Pointer for &'a T
- impl<'a, T: ?Sized> Pointer for &'a mut T
- impl<T: ?Sized> Pointer for *const T
- impl<T: ?Sized> Pointer for *mut T
- impl<T: ?Sized> fmt::Pointer for Box<T>
- impl<T: ?Sized> fmt::Pointer for Rc<T>
- impl<T: ?Sized> fmt::Pointer for Arc<T>
Issue #31109 uncovered two semi-related problems:
* A panic in `str::parse::<f64>`
* A panic in `rustc::middle::const_eval::lit_to_const` where the result of float parsing was unwrapped.
This series of commits fixes both issues and also drive-by-fixes some things I noticed while tracking down the parsing panic.
This is a behavior that some find confusing, so it deserves its own example.
Fixes#31318
I think this wording might be a bit strange, but I couldn't come up with anything better. Feedback very welcome.
