Pre-RFC: Arbitrary bit-width integers

language design
31

If uN covers the range [0, 2N) and iN covers the range [−2N − 1, 2N − 1), then u0 should cover [0, 1), while i0 should cover [−½, ½). The only integer in either range is zero. This removes the ambiguity. (Shamelessly stolen from scottmcm’s post.)

Alternatively, if we require that

  • <T as Default>::default().into<U>() == <U as Default>::default(),
  • iN : Default, and
  • iN : Into<iM> for N ≤ M,

then we also must have <i0 as Default>::default() be zero.

Back to the issue at hand: I would favour a solution where irregular-bit-width integers behave like ordinary types with respect to ABI, while bitpacking is solved by an orthogonal feature.

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