Macro static_assertions::assert_eq_size
source · macro_rules! assert_eq_size { ($x:ty, $($xs:ty),+ $(,)?) => { ... }; }
Expand description
Asserts that types are equal in size.
When performing operations such as pointer casts or dealing with usize
versus u64
versus u32
, the size of your types matter. That is where
this macro comes into play.
§Alternatives
There also exists assert_eq_size_val
and
assert_eq_size_ptr
. Instead of specifying
types to compare, values’ sizes can be directly compared against each other.
§Examples
These three types, despite being very different, all have the same size:
assert_eq_size!([u8; 4], (u16, u16), u32);
The following example fails to compile because u32
has 4 times the size of
u8
:
ⓘ
assert_eq_size!(u32, u8);