The `is_power_of_two()` method of the `UnsignedInt` trait currently returns `true` for `self == 0`. Zero is not a power of two, assuming an integral exponent `k >= 0`. I've therefore moved this functionality to the new method `is_power_of_two_or_zero()` and reformed `is_power_of_two()` to return false for `self == 0`.
To illustrate the usefulness of the existence of both functions, consider `HashMap`. Its capacity must be zero or a power of two; conversely, it also requires a (non-zero) power of two for key and val alignment.
Also, added a small amount of documentation regarding #18604.
This commit, like the second pass of `Option`, largely just stablizes the
existing functionality after renaming a few iterators.
The specific actions taken were:
* The `Ok` and `Err` variants were marked `#[stable]` as the stability
inheritance was since removed.
* The `as_mut` method is now stable.
* The `map` method is now stable
* The `map_err` method is now stable
* The `iter`, `iter_mut`, and `into_iter` methods now returned structures named
after the method of iteration. The methods are also now all stable.
* The `and_then` method is now stable.
* The `or_else` method is now stable.
* The `unwrap` family of functions are now all stable: `unwrap_or`,
`unwrap_or_else`, `unwrap`, and `unwrap_err`.
There is a possible open extension to `Result::{and, and_then}` to make the
return type further generic over `FromError` (as proposed in #19078), but this
is a backwards compatible change due to the usage of default type parameters,
which makes the two functions safe to stabilize now regardless of the outcome of
that issue.
This removes the type SetAlgebraItems and replaces it with the
structs Intersection and Difference.
Rename the existing HashSet iterators according to RFC #344:
* SetItems -> Iter
* SetMoveItems -> IntoIter
* Remaining set combination iterators renamed to Union and SymmetricDifference
[breaking-change]
parse_ty() no longer takes a boolean parameter. quote_ty! implementation has not yet been modified accordingly.
As a matter of fact, quote_ty! was not covered by tests. One test (called qquotes) references it, but it has been ignored for nearly one year and now need heavy refactoring.
quote_token.rs seemed like a good place to test quote_ty!, many other quote_*! macros were asserted there.
This commit shuffles around some CLI flags of the compiler to some more stable
locations with some renamings. The changes made were:
* The `-v` flag has been repurposes as the "verbose" flag. The version flag has
been renamed to `-V`.
* The `-h` screen has been split into two parts. Most top-level options (not
all) show with `-h`, and the remaining options (generally obscure) can be
shown with `--help -v` which is a "verbose help screen"
* The `-V` flag (version flag now) has lost its argument as it is now requested
with `rustc -vV` "verbose version".
* The `--emit` option has had its `ir` and `bc` variants renamed to `llvm-ir`
and `llvm-bc` to emphasize that they are LLVM's IR/bytecode.
* The `--emit` option has grown a new variant, `dep-info`, which subsumes the
`--dep-info` CLI argument. The `--dep-info` flag is now deprecated.
* The `--parse-only`, `--no-trans`, and `--no-analysis` flags have
moved behind the `-Z` family of flags.
* The `--debuginfo` and `--opt-level` flags were moved behind the top-level `-C`
flag.
* The `--print-file-name` and `--print-crate-name` flags were moved behind one
global `--print` flag which now accepts one of `crate-name`, `file-names`, or
`sysroot`. This global `--print` flag is intended to serve as a mechanism for
learning various metadata about the compiler itself.
No warnings are currently enabled to allow tools like Cargo to have time to
migrate to the new flags before spraying warnings to all users.
- Various grammatical changes
- Place punctuation outside of key term quotes
- Change comment placement in 17.2 code block
- Replace double hyphens with en dashes
Rewrite how the HRTB algorithm matches impls against obligations. Instead of impls providing higher-ranked trait-references, impls now once again only have early-bound regions. The skolemization checks are thus moved out into trait matching itself. This allows to implement "perfect forwarding" impls like those described in #19730. This PR builds on a previous PR that was already reviewed by @pnkfelix.
r? @pnkfelix
Fixes#19730
This fixes#19978. The bug was introduced by 570325d, where if the type
of an Fn has not been inferred (strs[0] is "_") we slice from 1 to
0. We now explicitly check if `strs[0]` is a single element tuple.
lifetimes. This currently causes an ICE; it should (ideally) work, but
failing that at least give a structured error. For the purposes of
this PR, though, workaround is fine.
