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Diffstat (limited to 'library/core/src/ffi/c_void.md')
| -rw-r--r-- | library/core/src/ffi/c_void.md | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/library/core/src/ffi/c_void.md b/library/core/src/ffi/c_void.md new file mode 100644 index 000000000..ee7403aa0 --- /dev/null +++ b/library/core/src/ffi/c_void.md @@ -0,0 +1,16 @@ +Equivalent to C's `void` type when used as a [pointer]. + +In essence, `*const c_void` is equivalent to C's `const void*` +and `*mut c_void` is equivalent to C's `void*`. That said, this is +*not* the same as C's `void` return type, which is Rust's `()` type. + +To model pointers to opaque types in FFI, until `extern type` is +stabilized, it is recommended to use a newtype wrapper around an empty +byte array. See the [Nomicon] for details. + +One could use `std::os::raw::c_void` if they want to support old Rust +compiler down to 1.1.0. After Rust 1.30.0, it was re-exported by +this definition. For more information, please read [RFC 2521]. + +[Nomicon]: https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs +[RFC 2521]: https://github.com/rust-lang/rfcs/blob/master/text/2521-c_void-reunification.md |