1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
#![stable(feature = "", since = "1.30.0")] #![allow(non_camel_case_types)] //! Utilities related to FFI bindings. use ::fmt; /// 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. /// /// Ideally, this type would be equivalent to [`!`], but currently it may /// be more ideal to use `c_void` for FFI purposes. /// /// [`!`]: ../../std/primitive.never.html /// [pointer]: ../../std/primitive.pointer.html // NB: For LLVM to recognize the void pointer type and by extension // functions like malloc(), we need to have it represented as i8* in // LLVM bitcode. The enum used here ensures this and prevents misuse // of the "raw" type by only having private variants.. We need two // variants, because the compiler complains about the repr attribute // otherwise. #[repr(u8)] #[stable(feature = "raw_os", since = "1.1.0")] pub enum c_void { #[unstable(feature = "c_void_variant", reason = "should not have to exist", issue = "0")] #[doc(hidden)] __variant1, #[unstable(feature = "c_void_variant", reason = "should not have to exist", issue = "0")] #[doc(hidden)] __variant2, } #[stable(feature = "std_debug", since = "1.16.0")] impl fmt::Debug for c_void { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.pad("c_void") } }