diff --git a/library/core/src/fmt/num.rs b/library/core/src/fmt/num.rs index ba30518d70bc2..dd9c379b666de 100644 --- a/library/core/src/fmt/num.rs +++ b/library/core/src/fmt/num.rs @@ -678,8 +678,8 @@ impl fmt::Display for i128 { /// It also has to handle 1 last item, as 10^40 > 2^128 > 10^39, whereas /// 10^20 > 2^64 > 10^19. fn fmt_u128(n: u128, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result { - // 2^128 is about 3*10^38, so 39 gives an extra byte of space - let mut buf = [MaybeUninit::::uninit(); 39]; + const MAX_DEC_N: usize = u128::MAX.ilog(10) as usize + 1; + let mut buf = [MaybeUninit::::uninit(); MAX_DEC_N]; let mut curr = buf.len(); let (n, rem) = udiv_1e19(n);