This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.
The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:
* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
`cfg(libc_unions)` and not available on older Rust versions.
* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
Rust versions, all uses of `repr(align)` are split into `align.rs` and
`no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
level. These modules sometimes contain macros that are expanded at the top
level to avoid privacy issues (`pub(crate)` is not available in older Rust
versions). Closes#1242 .
* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
constants on older Rust versions.
Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked
in #1243. Also, `extra_traits` does not enable `align` manually anymore.
Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.
Closes#1232 .
This commit prepares the `libc` crate to be included directly into the
standard library via crates.io. More details about this can be found on
rust-lang/rust#56092, but the main idea is that this crate now depends
on core/compiler-builtins explicitly (but off-by-default).
The main caveat here is that this activates `no_core` when building as
part of libstd, which means that it needs to explicitly have an `iter`
and `option` module for the expansion of `for` loops to work.
- add DCCP constant definitions
- add clock_gettime related functions to macOS
- add fstatat64 on linux/android
- add preadv64/pwritev64 on linux/android
- add utimensat on solaris, netbsd and openbsd
- add IP_BINDANY on freebsd
It's now broken due to changes in the `gcc` crate and having a too-old compiler,
and in general it's unfortunately architecturally so different from the other
test frameworks that it's difficult to maintain over time.
