mirror of https://github.com/rust-lang/rust
44 lines
977 B
Rust
44 lines
977 B
Rust
//@ run-pass
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#![feature(test)]
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extern crate test;
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use test::black_box;
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#[allow(dead_code)]
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#[repr(u8)]
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enum Enum {
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Unit = 3,
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Tuple(u16) = 2,
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Struct {
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a: u8,
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b: u16,
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} = 1,
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}
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impl Enum {
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const unsafe fn tag(&self) -> u8 {
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*(self as *const Self as *const u8)
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}
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}
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fn main() {
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const UNIT: Enum = Enum::Unit;
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const TUPLE: Enum = Enum::Tuple(5);
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const STRUCT: Enum = Enum::Struct{a: 7, b: 11};
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// Ensure discriminants are correct during runtime execution
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assert_eq!(3, unsafe { black_box(UNIT).tag() });
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assert_eq!(2, unsafe { black_box(TUPLE).tag() });
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assert_eq!(1, unsafe { black_box(STRUCT).tag() });
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// Ensure discriminants are correct during CTFE
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const UNIT_TAG: u8 = unsafe { UNIT.tag() };
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const TUPLE_TAG: u8 = unsafe { TUPLE.tag() };
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const STRUCT_TAG: u8 = unsafe { STRUCT.tag() };
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assert_eq!(3, UNIT_TAG);
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assert_eq!(2, TUPLE_TAG);
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assert_eq!(1, STRUCT_TAG);
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}
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