ignore higher-ranked object bound conditions created by WF
In the `issue-53548` test added in this PR, the `Box<dyn Trait>` type is expanded to `Box<dyn Trait + 'static>`, but the generator "witness" that results is `for<'r> { Box<dyn Trait + 'r> }`. The WF code was encountering an ICE (when debug-assertions were enabled) and an unexpected compilation error (without debug-asserions) when trying to process this `'r` region bound. In particular, to be WF, the region bound must meet the requirements of the trait, and hence we got `for<'r> { 'r: 'static }`. This would ICE because the `Binder` constructor we were using was assering that no higher-ranked regions were involved (because the WF code is supposed to skip those). The error (if debug-asserions were disabled) came because we obviously cannot prove that `'r: 'static` for any region `'r`. Pursuant with
our "lazy WF" strategy for higher-ranked regions, the fix is not to require that `for<'r> { 'r: 'static }` holds (this is also analogous to what we would do for higher-ranked regions appearing within the trait in other positions).
Fixes#53548
r? @pnkfelix
Reduces Code Repetitions like `!n >> amt`
Fixes#49937 .
This PR contains defining a function which operates bit inversion and reducing bit operation like `!0u128 >> (128 - size.bits())`.
Fix#54822 and associated faulty tests
Type checking associated constants can require trait bounds, but an empty
parameter environment was provided to the trait solver. Providing an
appropriate parameter environment seems to fix#54822 and also make one of the
cases in src/test/ui/nll/trait-associated-constant.rs that should compile
successfully do so. It also (slightly) improves the error message in
src/test/ui/associated-const/associated-const-generic-obligations.rs
Standardize `Range*` documentation
This updates the final example in the documentation for the types
`Range`, `RangeFrom`, `RangeFull`, `RangeInclusive`, `RangeTo`,
`RangeToInclusive`.
Use lifetime contravariance to elide more lifetimes in core+alloc+std
Sample:
```diff
- impl<'a, 'b, A: ?Sized, B: ?Sized> PartialEq<&'b mut B> for &'a mut A where A: PartialEq<B> {
+ impl<A: ?Sized, B: ?Sized> PartialEq<&mut B> for &mut A where A: PartialEq<B> {
#[inline]
- fn eq(&self, other: &&'b mut B) -> bool { PartialEq::eq(*self, *other) }
+ fn eq(&self, other: &&mut B) -> bool { PartialEq::eq(*self, *other) }
#[inline]
- fn ne(&self, other: &&'b mut B) -> bool { PartialEq::ne(*self, *other) }
+ fn ne(&self, other: &&mut B) -> bool { PartialEq::ne(*self, *other) }
}
```
[I didn't know this worked](https://internals.rust-lang.org/t/why-can-you-use-different-unconstrained-lifetimes-to-implement-traits/9544/2?u=scottmcm) until recently, but since defining methods contravariantly in their lifetimes this way has worked back to Rust 1.0, we might as well take advantage of combining it with IHLE.
Fix documentation of from_ne_bytes and from_le_bytes
Copypasta mistake, the documentation of `from_ne_bytes` and `from_le_bytes` used the big-endian variant in the example snippets.
Expand docs for `TryFrom` and `TryInto`.
The examples are still lacking for now, both for module docs and for methods/impl's. Will be adding those in further pushes.
Should hopefully resolve the doc concern in #33417 when finished?
In the `issue-53548` test added in this commit, the `Box<dyn Trait>`
type is expanded to `Box<dyn Trait + 'static>`, but the generator
"witness" that results is `for<'r> { Box<dyn Trait + 'r> }`. The WF
code was encountering an ICE (when debug-assertions were enabled) and
an unexpected compilation error (without debug-asserions) when trying
to process this `'r` region bound. In particular, to be WF, the region
bound must meet the requirements of the trait, and hence we got
`for<'r> { 'r: 'static }`. This would ICE because the `Binder`
constructor we were using was assering that no higher-ranked regions
were involved (because the WF code is supposed to skip those). The
error (if debug-asserions were disabled) came because we obviously
cannot prove that `'r: 'static` for any region `'r`. Pursuant with
our "lazy WF" strategy for higher-ranked regions, the fix is not to
require that `for<'r> { 'r: 'static }` holds (this is also analogous
to what we would do for higher-ranked regions appearing within the
trait in other positions).
