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
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/
* De-indent quite a bit by removing usage of FnOnce closures
* Clearly separate code for the parent/child after the fork
* Use `fs2::{File, OpenOptions}` instead of calling `open` manually
* Use RAII to close I/O objects wherever possible
* Remove loop for closing all file descriptors, all our own ones are now
`CLOEXEC` by default so they cannot be inherited
