| // compile-flags: -Z print-type-sizes |
| // build-pass (FIXME(62277): could be check-pass?) |
| // ignore-pass |
| // ^-- needed because `--pass check` does not emit the output needed. |
| // FIXME: consider using an attribute instead of side-effects. |
| |
| // This file illustrates how niche-filling enums are handled, |
| // modelled after cases like `Option<&u32>`, `Option<bool>` and such. |
| // |
| // It uses NonZeroU32 rather than `&_` or `Unique<_>`, because |
| // the test is not set up to deal with target-dependent pointer width. |
| // |
| // It avoids using u64/i64 because on some targets that is only 4-byte |
| // aligned (while on most it is 8-byte aligned) and so the resulting |
| // padding and overall computed sizes can be quite different. |
| |
| #![feature(start)] |
| #![allow(dead_code)] |
| |
| use std::num::NonZeroU32; |
| |
| pub enum MyOption<T> { None, Some(T) } |
| |
| impl<T> Default for MyOption<T> { |
| fn default() -> Self { MyOption::None } |
| } |
| |
| pub enum EmbeddedDiscr { |
| None, |
| Record { pre: u8, val: NonZeroU32, post: u16 }, |
| } |
| |
| impl Default for EmbeddedDiscr { |
| fn default() -> Self { EmbeddedDiscr::None } |
| } |
| |
| #[derive(Default)] |
| pub struct IndirectNonZero { |
| pre: u8, |
| nested: NestedNonZero, |
| post: u16, |
| } |
| |
| pub struct NestedNonZero { |
| pre: u8, |
| val: NonZeroU32, |
| post: u16, |
| } |
| |
| impl Default for NestedNonZero { |
| fn default() -> Self { |
| NestedNonZero { pre: 0, val: NonZeroU32::new(1).unwrap(), post: 0 } |
| } |
| } |
| |
| pub enum Enum4<A, B, C, D> { |
| One(A), |
| Two(B), |
| Three(C), |
| Four(D) |
| } |
| |
| pub union Union1<A: Copy> { |
| a: A, |
| } |
| |
| pub union Union2<A: Copy, B: Copy> { |
| a: A, |
| b: B, |
| } |
| |
| #[start] |
| fn start(_: isize, _: *const *const u8) -> isize { |
| let _x: MyOption<NonZeroU32> = Default::default(); |
| let _y: EmbeddedDiscr = Default::default(); |
| let _z: MyOption<IndirectNonZero> = Default::default(); |
| let _a: MyOption<bool> = Default::default(); |
| let _b: MyOption<char> = Default::default(); |
| let _c: MyOption<std::cmp::Ordering> = Default::default(); |
| let _b: MyOption<MyOption<u8>> = Default::default(); |
| let _e: Enum4<(), char, (), ()> = Enum4::One(()); |
| let _f: Enum4<(), (), bool, ()> = Enum4::One(()); |
| let _g: Enum4<(), (), (), MyOption<u8>> = Enum4::One(()); |
| |
| // Unions do not currently participate in niche filling. |
| let _h: MyOption<Union2<NonZeroU32, u32>> = Default::default(); |
| |
| // ...even when theoretically possible. |
| let _i: MyOption<Union1<NonZeroU32>> = Default::default(); |
| let _j: MyOption<Union2<NonZeroU32, NonZeroU32>> = Default::default(); |
| |
| 0 |
| } |