a17a91cdbf
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 .
66 lines
1.9 KiB
Rust
66 lines
1.9 KiB
Rust
use std::env;
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use std::process::Command;
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use std::str;
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fn main() {
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let rustc_minor_ver =
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rustc_minor_version().expect("Failed to get rustc version");
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let rustc_dep_of_std =
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std::env::var("CARGO_FEATURE_RUSTC_DEP_OF_STD").is_ok();
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let align_cargo_feature = std::env::var("CARGO_FEATURE_ALIGN").is_ok();
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// Rust >= 1.15 supports private module use:
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if rustc_minor_ver >= 15 || rustc_dep_of_std {
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println!("cargo:rustc-cfg=libc_priv_mod_use");
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}
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// Rust >= 1.19 supports unions:
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if rustc_minor_ver >= 19 || rustc_dep_of_std {
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println!("cargo:rustc-cfg=libc_union");
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}
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// Rust >= 1.24 supports const mem::size_of:
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if rustc_minor_ver >= 24 || rustc_dep_of_std {
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println!("cargo:rustc-cfg=libc_const_size_of");
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}
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// Rust >= 1.25 supports repr(align):
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if rustc_minor_ver >= 25 || rustc_dep_of_std || align_cargo_feature {
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println!("cargo:rustc-cfg=libc_align");
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}
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// Rust >= 1.30 supports `core::ffi::c_void`, so libc can just re-export it.
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// Otherwise, it defines an incompatible type to retaining
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// backwards-compatibility.
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if rustc_minor_ver >= 30 || rustc_dep_of_std {
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println!("cargo:rustc-cfg=libc_core_cvoid");
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}
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// Rust >= 1.33 supports repr(packed(N))
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if rustc_minor_ver >= 33 || rustc_dep_of_std {
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println!("cargo:rustc-cfg=libc_packedN");
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}
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}
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fn rustc_minor_version() -> Option<u32> {
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macro_rules! otry {
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($e:expr) => {
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match $e {
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Some(e) => e,
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None => return None,
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}
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};
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}
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let rustc = otry!(env::var_os("RUSTC"));
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let output = otry!(Command::new(rustc).arg("--version").output().ok());
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let version = otry!(str::from_utf8(&output.stdout).ok());
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let mut pieces = version.split('.');
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if pieces.next() != Some("rustc 1") {
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return None;
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}
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otry!(pieces.next()).parse().ok()
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}
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