Use `discriminant_value` intrinsic for `derive(PartialOrd)`
[breaking-change]
This is a [breaking-change] because it can change the result of comparison operators when enum discriminants have been explicitly assigned. Notably in a case like:
```rust
#[derive(PartialOrd)]
enum E { A = 2, B = 1}
```
Under the old deriving, `A < B` held, because `A` came before `B` in the order of declaration. But now we use the ordering according to the provided values, and thus `A > B`. (However, this change is very unlikely to break much, if any, code, since the orderings themselves should all remain well-defined, total, etc.)
Fix#15523
The meaning of each variant of this enum was somewhat ambiguous and it's uncler
that we wouldn't even want to add more enumeration values in the future. As a
result this error has been altered to instead become an opaque structure.
Learning about the "first invalid byte index" is still an unstable feature, but
the type itself is now stable.
This commit series starts out with more official test harness support for rustdoc tests, and then each commit afterwards adds a test (where appropriate). Each commit should also test and finish independently of all others (they're all pretty separable).
I've uploaded a [copy of the documentation](http://people.mozilla.org/~acrichton/doc/std/) generated after all these commits were applied, and a double check on issues being closed would be greatly appreciated! I'll also browse the docs a bit and make sure nothing regressed too horribly.
The commit messages have more details as to what's going on, but this is a breaking change for any libraries which expect file descriptors to be inherited by default.
Closes#12148
Implements an intrinsic for extracting the value of the discriminant
enum variant values. For non-enum types, this returns zero, otherwise it
returns the value we use for discriminant comparisons. This means that
enum types that do not have a discriminant will also work in this
arrangement.
This is (at least part of) the work on Issue #24263
The logic for only closing file descriptors >= 3 was inherited from quite some
time ago and ends up meaning that some internal APIs are less consistent than
they should be. By unconditionally closing everything entering a `FileDesc` we
ensure that we're consistent in our behavior as well as robustly handling the
stdio case.
The main change in this patch is removing the use of `Option` inside the
inner loops of those functions to avoid comparisons where one branch
will only trigger on the first pass through the loop.
The included benchmarks go from:
test bench_max ... bench: 372 ns/iter (+/- 118)
test bench_max_by ... bench: 428 ns/iter (+/- 33)
test bench_max_by2 ... bench: 7128 ns/iter (+/- 326)
to:
test bench_max ... bench: 317 ns/iter (+/- 64)
test bench_max_by ... bench: 356 ns/iter (+/- 270)
test bench_max_by2 ... bench: 1387 ns/iter (+/- 183)
Problem noticed in http://www.reddit.com/r/rust/comments/31syce/using_iterators_to_find_the_index_of_the_min_or/
The main change in this patch is removing the use of `Option` inside the
inner loops of those functions to avoid comparisons where one branch
will only trigger on the first pass through the loop.
The included benchmarks go from:
test bench_max ... bench: 372 ns/iter (+/- 118)
test bench_max_by ... bench: 428 ns/iter (+/- 33)
test bench_max_by2 ... bench: 7128 ns/iter (+/- 326)
to:
test bench_max ... bench: 317 ns/iter (+/- 64)
test bench_max_by ... bench: 356 ns/iter (+/- 270)
test bench_max_by2 ... bench: 1387 ns/iter (+/- 183)
Problem noticed in http://www.reddit.com/r/rust/comments/31syce/using_iterators_to_find_the_index_of_the_min_or/
