> plus 8 bytes for the tag
The tag can often be stored inline in the data, so doesn't necessarily require extra space.
> because they always take up as much space as the largest wrapped type
Yeah... but what's the alternative?
The tag can often be stored inline in the data, so doesn't necessarily require extra space.
> because they always take up as much space as the largest wrapped type
Yeah... but what's the alternative?
enum Foo {
Bar,
Qux([i32; 1024]),
}
enum Foo {
Bar,
Qux(Box<[i32; 1024]>),
}
Today, clippy does what I think is the right thing: it teaches the user
warning: large size difference between variants
--> src/main.rs:1:1
|
1 | / enum Foo {
2 | | Bar,
| | --- the second-largest variant carries no data at all
3 | | Qux([i32; 1024]),
| | ---------------- the largest variant contains at least 4096 bytes
4 | | }
| |_^ the entire enum is at least 4100 bytes
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#large_enum_variant
= note: `#[warn(clippy::large_enum_variant)]` on by default
help: consider boxing the large fields to reduce the total size of the enum
|
3 | Qux(Box<[i32; 1024]>),
| ~~~~~~~~~~~~~~~~