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Layout::pad_to_align is infallible

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Christopher Durham 2019-11-09 15:19:09 -05:00 • committed by GitHub
parent eb981a1da4
commit fd3594b9ee
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1 changed files with 7 additions and 5 deletions
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12
src/libcore/alloc.rs
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@ -213,16 +213,18 @@ impl Layout {
/// Creates a layout by rounding the size of this layout up to a multiple
/// of the layout's alignment.
///
/// Returns `Err` if the padded size would overflow.
///
/// This is equivalent to adding the result of `padding_needed_for`
/// to the layout's current size.
#[unstable(feature = "alloc_layout_extra", issue = "55724")]
#[inline]
pub fn pad_to_align(&self) -> Result<Layout, LayoutErr> {
pub fn pad_to_align(&self) -> Layout {
let pad = self.padding_needed_for(self.align());
let new_size = self.size().checked_add(pad)
.ok_or(LayoutErr { private: () })?;
// This cannot overflow: it is an invariant of Layout that
// > `size`, when rounded up to the nearest multiple of `align`,
// > must not overflow (i.e., the rounded value must be less than
// > `usize::MAX`)
let new_size = self.size() + pad;
debug_assert!(new_size > self.size());
Layout::from_size_align(new_size, self.align())
}