Last change
on this file since 1842167 was
1725989,
checked in by Peter A. Buhr <pabuhr@…>, 2 months ago
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add enumeration test programs for different programming languages
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Property mode set to
100644
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File size:
825 bytes
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Line | |
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1 | use std::mem; |
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2 | |
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3 | #[repr(u8)] enum Fieldless { |
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4 | Tuple() = 5, |
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5 | Struct{} = 10, |
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6 | Unit = 12, |
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7 | } |
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8 | impl Fieldless { |
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9 | fn discriminant(&self) -> u8 { |
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10 | // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union` |
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11 | // between `repr(C)` structs, each of which has the `u8` discriminant as its first |
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12 | // field, so we can read the discriminant without offsetting the pointer. |
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13 | unsafe { *<*const _>::from(self).cast::<u8>() } |
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14 | } |
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15 | } |
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16 | fn main() { |
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17 | let mut fl : Fieldless; |
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18 | fl = Fieldless::Struct{}; |
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19 | match fl { |
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20 | Fieldless::Struct{} => println!( "Struct" ), |
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21 | _ => (), |
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22 | } |
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23 | if mem::discriminant(&fl) == mem::discriminant(&Fieldless::Struct{}) { |
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24 | println!( "Struct" ); |
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25 | } |
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26 | if fl.discriminant() == 10 { |
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27 | println!( "Struct" ); |
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28 | } |
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29 | } |
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30 | |
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31 | // Local Variables: // |
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32 | // tab-width: 4 // |
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33 | // End: // |
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