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uint: Make is_zero implementation const #639

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Apr 4, 2022
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uint: Make is_zero implementation const #639

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5 changes: 3 additions & 2 deletions uint/src/uint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -673,9 +673,10 @@ macro_rules! construct_uint {

/// Whether this is zero.
#[inline]
pub fn is_zero(&self) -> bool {
pub const fn is_zero(&self) -> bool {
let &$name(ref arr) = self;
for i in 0..$n_words { if arr[i] != 0 { return false; } }
let mut i = 0;
while i < $n_words { if arr[i] != 0 { return false; } else { i += 1; } }
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so while is now stable to loop over in const context but for not yet? interesting, seemed like all of them are behind const_looping

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Yeah, for loop calls iter.next() which is not a const fn.
Future RFCs (like rust-lang/rfcs#2237) might lift that restriction.

return true;
}

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