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Robbepop/const_eval_for_next_power_of_two.rs

Created October 25, 2020 21:47
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Constant evulator for next_power_of_two in proc. macros.
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const_eval_for_next_power_of_two.rs
fn const_next_power_of_two(ty: TokenStream2, value: TokenStream2) -> TokenStream2 {
quote! {{
if (#value) <= 1 {
0
} else {
let p = (#value) - 1;
let z = p.leading_zeros();
<#ty>::MAX as usize >> z
}
}}
}
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