Add alignment feature and use #[repr(align(x))]
Trying to solve #1042.
Here I introduce the discussed feature that will allow going from struct alignment with a private `__align` field to using `#[repr(align(x))]`. However, I have not implemented it for all structs that require alignment yet, only `in6_addr`. This because I did not want to spend too much time before we have discussed and solved the remaining questions regarding this.
One thing to discuss is testing. I have so far not done anything to the CI scripts. So currently they will still test the crate only with the `align` feature disabled. Thus they will make sure the `__align` fields are still correct. But no automatic tests make sure everything is correct when the `align` feature is turned on. What do we want to do about that? Can we insert another `cargo test` with `--features align` to make all the Travis jobs run the test suite twice, or will that slow things down too much?
I have tried using this version of libc in rustc and the standard library. And successfully changed `Ipv6Addr::new` to not use any `unsafe` and to become a `const fn`. Whether or not we want that is out of scope for this PR, but my point was that the changes introduced with this PR allow much more flexible usage of the libc structs that have alignment.
Openbsd fix
put in several fixes for OpenBSD (one fix per commit).
testsuite ran on OpenBSD 6.3-current (upcoming 6.4)
```
RUNNING ALL TESTS
PASSED 6474 tests
```
Bump ctest from `482c7f0` to `5c53723`
Bumps [ctest](https://github.com/alexcrichton/ctest) from `482c7f0` to `5c53723`.
<details>
<summary>Commits</summary>
- [`5c53723`](5c537236d1) Update libc dep
- See full diff in [compare view](482c7f0643...5c537236d1)
</details>
<br />
Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`.
---
**Note:** This repo was added to Dependabot recently, so you'll receive a maximum of 5 PRs for your first few update runs. Once an update run creates fewer than 5 PRs we'll remove that limit.
You can always request more updates by clicking `Bump now` in your [Dependabot dashboard](https://app.dependabot.com).
<details>
<summary>Dependabot commands and options</summary>
<br />
You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot merge` will merge this PR after your CI passes on it
- `@dependabot ignore this [patch|minor|major] version` will close this PR and stop Dependabot creating any more for this minor/major version (unless you reopen the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
- `@dependabot use these labels` will set the current labels as the default for future PRs for this repo and language
- `@dependabot use these reviewers` will set the current reviewers as the default for future PRs for this repo and language
- `@dependabot use these assignees` will set the current assignees as the default for future PRs for this repo and language
- `@dependabot badge me` will comment on this PR with code to add a "Dependabot enabled" badge to your readme
Additionally, you can set the following in your Dependabot [dashboard](https://app.dependabot.com):
- Update frequency (including time of day and day of week)
- Automerge options (never/patch/minor, and dev/runtime dependencies)
- Pull request limits (per update run and/or open at any time)
- Out-of-range updates (receive only lockfile updates, if desired)
- Security updates (receive only security updates, if desired)
Finally, you can contact us by mentioning @dependabot.
</details>
Add linux musl powerpc (32-bit) support
This change adds support for musl on 32-bit powerpc. Most of the general constants in src/unix/notbsd/linux/musl/b32/mod.rs were different from those of the powerpc port, so I moved them over to the individual architecture-specific submodules. The same with the ipc_perm structure.
Add ENOATTR for Android
PR based on https://github.com/rust-lang/libc/pull/594
It's defined in Android sysroot so it should work without test workaround (CI should catch it otherwise?).
Re-add aarch64 stuff removed by previous PR
Previous PR #1023 has removed stuff from mod.rs and added it to some submodules, but
missed the aarch64 submodule.
This caused a build failure for rust on aarch64, see https://github.com/rust-lang/rust/pull/51864.
This copies the stuff that that commit added to the x86_64.rs submodule
and puts it into aarch64.rs.
It's been tested in the rust-lang/rust PR above: https://travis-ci.org/rust-lang/rust/builds/398750336
