Function layout_extend 

pub const fn layout_extend(
    a: Layout,
    b: Layout,
) -> Result<(Layout, usize), InvLayout>

Given two layouts a and b, computes a layout describing a block of memory that can hold a value of layout a followed by a value of layout b, where b starts at an offset that satisfies its alignment. Returns the resulting combined layout and the offset at which b begins.

Errors

Returns InvLayout when the resulting size or alignment would exceed USIZE_MAX_NO_HIGH_BIT.