libc: add padding struct

Author: mbyx

src/lib.rs

@@ -43,6 +43,8 @@ pub use core::ffi::c_void;
 #[allow(unused_imports)] // needed while the module is empty on some platforms
 pub use new::*;
 
+mod types;
+
 cfg_if! {
     if #[cfg(windows)] {
         mod primitives;

src/macros.rs

@@ -86,6 +86,9 @@ macro_rules! prelude {
                 c_char, c_double, c_float, c_int, c_long, c_longlong, c_short, c_uchar, c_uint,
                 c_ulong, c_ulonglong, c_ushort, c_void, intptr_t, size_t, ssize_t, uintptr_t,
             };
+
+            #[allow(unused_imports)]
+            pub(crate) use crate::types::Padding;
         }
     };
 }

src/types.rs

@@ -0,0 +1,16 @@
+//! Platform-agnostic support types.
+
+use core::mem::MaybeUninit;
+
+/// A transparent wrapper over `MaybeUninit<T>` to represent uninitialized padding
+/// while providing `Default`.
+#[allow(unused)]
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub(crate) struct Padding<T: Copy>(MaybeUninit<T>);
+
+impl<T: Copy> Default for Padding<T> {
+    fn default() -> Self {
+        Self(MaybeUninit::zeroed())
+    }
+}