Created
August 25, 2019 05:43
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fn main(){ | |
let _:i8=0u8.cast(); | |
let _:i16=0u8.cast(); | |
let _:i32=0u8.cast(); | |
let _:i8=0u16.cast(); | |
let _:i16=0u16.cast(); | |
let _:i32=0u16.cast(); | |
let _:i8=0u32.cast(); | |
let _:i16=0u32.cast(); | |
let _:i32=0u32.cast(); | |
} | |
trait Cast<T>{ | |
fn cast(self)->T; | |
} | |
macro_rules! cartesian_producs_of_impls { | |
( row[ $($row:ty),* ] col[ $($col:ty),* ] )=>{ | |
cartesian_producs_of_impls!{inner | |
state() | |
row[$($row),*] | |
col[$($col),*] | |
} | |
}; | |
(inner state($($tokens:tt)*) row[] col[ $($col:ty),* ] )=>{ | |
$($tokens)* | |
}; | |
(inner | |
state($($tokens:tt)*) | |
row[ $first_one:ty $(,$rem:ty)* ] | |
col[ $($col:ty),* ] | |
)=>{ | |
cartesian_producs_of_impls!{inner | |
state( | |
$($tokens)* | |
$( | |
impl Cast<$col> for $first_one{ | |
fn cast(self)->$col{ | |
self as _ | |
} | |
} | |
)* | |
) | |
row[$($rem),*] | |
col[$($col),*] | |
} | |
}; | |
} | |
cartesian_producs_of_impls!{ | |
row[u8,u16,u32] | |
col[i8,i16,i32] | |
} |
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