XCTAssertEqual(64, BigInt(Int64.min).bitWidth)
That fails, because bitWidth returns 65. It's not correctly handling the cases of 0b1 followed by some number of 0b0's, because with two's complement the magnitude of your minimum value is one higher than of your maximum value. Doing magnitude.bitWidth + 1 fails to account for this.
That fails, because bitWidth returns 65. It's not correctly handling the cases of 0b1 followed by some number of 0b0's, because with two's complement the magnitude of your minimum value is one higher than of your maximum value. Doing
magnitude.bitWidth + 1fails to account for this.