libc/
fixed_width_ints.rs

1//! This module contains type aliases for C's fixed-width integer types .
2//!
3//! These aliases are deprecated: use the Rust types instead.
4
5#[deprecated(since = "0.2.55", note = "Use i8 instead.")]
6pub type int8_t = i8;
7#[deprecated(since = "0.2.55", note = "Use i16 instead.")]
8pub type int16_t = i16;
9#[deprecated(since = "0.2.55", note = "Use i32 instead.")]
10pub type int32_t = i32;
11#[deprecated(since = "0.2.55", note = "Use i64 instead.")]
12pub type int64_t = i64;
13#[deprecated(since = "0.2.55", note = "Use u8 instead.")]
14pub type uint8_t = u8;
15#[deprecated(since = "0.2.55", note = "Use u16 instead.")]
16pub type uint16_t = u16;
17#[deprecated(since = "0.2.55", note = "Use u32 instead.")]
18pub type uint32_t = u32;
19#[deprecated(since = "0.2.55", note = "Use u64 instead.")]
20pub type uint64_t = u64;
21
22cfg_if! {
23    if #[cfg(all(libc_int128, target_arch = "aarch64", not(target_os = "windows")))] {
24        // This introduces partial support for FFI with __int128 and
25        // equivalent types on platforms where Rust's definition is validated
26        // to match the standard C ABI of that platform.
27        //
28        // Rust does not guarantee u128/i128 are sound for FFI, and its
29        // definitions are in fact known to be incompatible. [0]
30        //
31        // However these problems aren't fundamental, and are just platform
32        // inconsistencies. Specifically at the time of this writing:
33        //
34        // * For x64 SysV ABIs (everything but Windows), the types are underaligned.
35        // * For all Windows ABIs, Microsoft doesn't actually officially define __int128,
36        //   and as a result different implementations don't actually agree on its ABI.
37        //
38        // But on the other major aarch64 platforms (android, linux, ios, macos) we have
39        // validated that rustc has the right ABI for these types. This is important because
40        // aarch64 uses these types in some fundamental OS types like user_fpsimd_struct,
41        // which represents saved simd registers.
42        //
43        // Any API which uses these types will need to `#[ignore(improper_ctypes)]`
44        // until the upstream rust issue is resolved, but this at least lets us make
45        // progress on platforms where this type is important.
46        //
47        // The list of supported architectures and OSes is intentionally very restricted,
48        // as careful work needs to be done to verify that a particular platform
49        // has a conformant ABI.
50        //
51        // [0]: https://github.com/rust-lang/rust/issues/54341
52
53        /// C `__int128` (a GCC extension that's part of many ABIs)
54        pub type __int128 = i128;
55        /// C `unsigned __int128` (a GCC extension that's part of many ABIs)
56        pub type __uint128 = u128;
57        /// C __int128_t (alternate name for [__int128][])
58        pub type __int128_t = i128;
59        /// C __uint128_t (alternate name for [__uint128][])
60        pub type __uint128_t = u128;
61
62        cfg_if! {
63            if #[cfg(libc_underscore_const_names)] {
64                macro_rules! static_assert_eq {
65                    ($a:expr, $b:expr) => {
66                        const _: [(); $a] = [(); $b];
67                    };
68                }
69
70                // NOTE: if you add more platforms to here, you may need to cfg
71                // these consts. They should always match the platform's values
72                // for `sizeof(__int128)` and `_Alignof(__int128)`.
73                const _SIZE_128: usize = 16;
74                const _ALIGN_128: usize = 16;
75
76                // Since Rust doesn't officially guarantee that these types
77                // have compatible ABIs, we const assert that these values have the
78                // known size/align of the target platform's libc. If rustc ever
79                // tries to regress things, it will cause a compilation error.
80                //
81                // This isn't a bullet-proof solution because e.g. it doesn't
82                // catch the fact that llvm and gcc disagree on how x64 __int128
83                // is actually *passed* on the stack (clang underaligns it for
84                // the same reason that rustc *never* properly aligns it).
85                static_assert_eq!(core::mem::size_of::<__int128>(), _SIZE_128);
86                static_assert_eq!(core::mem::align_of::<__int128>(), _ALIGN_128);
87
88                static_assert_eq!(core::mem::size_of::<__uint128>(), _SIZE_128);
89                static_assert_eq!(core::mem::align_of::<__uint128>(), _ALIGN_128);
90
91                static_assert_eq!(core::mem::size_of::<__int128_t>(), _SIZE_128);
92                static_assert_eq!(core::mem::align_of::<__int128_t>(), _ALIGN_128);
93
94                static_assert_eq!(core::mem::size_of::<__uint128_t>(), _SIZE_128);
95                static_assert_eq!(core::mem::align_of::<__uint128_t>(), _ALIGN_128);
96            }
97        }
98    }
99}
libc/fixed_width_ints.rs

libc/
fixed_width_ints.rs
