Fix build on all platforms
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 .
diff --git a/src/unix/bsd/netbsdlike/openbsdlike/openbsd/x86.rs b/src/unix/bsd/netbsdlike/openbsdlike/openbsd/x86.rs
index b63b69f..959c87b 100644
--- a/src/unix/bsd/netbsdlike/openbsdlike/openbsd/x86.rs
+++ b/src/unix/bsd/netbsdlike/openbsdlike/openbsd/x86.rs
@@ -5,5 +5,12 @@
pub type c_char = i8;
// should be pub(crate), but that requires Rust 1.18.0
-#[doc(hidden)]
-pub const _ALIGNBYTES: usize = mem::size_of::<::c_int>() - 1;
+cfg_if! {
+ if #[cfg(libc_const_size_of)] {
+ #[doc(hidden)]
+ pub const _ALIGNBYTES: usize = mem::size_of::<::c_int>() - 1;
+ } else {
+ #[doc(hidden)]
+ pub const _ALIGNBYTES: usize = 4 - 1;
+ }
+}