Bug 22771 – BigInt divMod can return "-0" (negative zero)

Overview: In certain cases, when using divMod from std.bigint, it can return remainder value as "-0" which is incorrect and can causes some logical errors when the remainder is compared with 0. The issue happens in case of negative numbers and seems to be a logical error in the divMod function: https://github.com/dlang/phobos/blob/2629671c1556a81c4e7eef26e16b331c960e2b6f/std/bigint.d#L2247. Here the sign is directly copied from the dividend without considering that the remainder itself can be zero. Comparing the returned remainder with 0 leads to unexpected logical errors. The bug is a bit similar to the one resolved here: https://issues.dlang.org/show_bug.cgi?id=14124 Steps to Reproduce: It is present in the currently latest version on D and can be reproduced online currently (https://run.dlang.io/is/YsaAq8) Minimal reproduction code: void main() { import std.bigint; BigInt dividend = "-50"; BigInt divisor = "1"; BigInt quotient, remainder; divMod(dividend, divisor, quotient, remainder); assert(remainder == 0); // This is false, remainder is "-0" }

@dkorpel created dlang/phobos pull request #8379 "Fix issue 22771 - BigInt divMod can return "-0" (negative zero)" fixing this issue: - Fix issue 22771 - BigInt divMod can return "-0" (negative zero) https://github.com/dlang/phobos/pull/8379

dlang/phobos pull request #8379 "Fix issue 22771 - BigInt divMod can return "-0" (negative zero)" was merged into master: - 6a50e2c05067ecaca8df175e5307f70dbe34c8e1 by dkorpel: Fix issue 22771 - BigInt divMod can return "-0" (negative zero) https://github.com/dlang/phobos/pull/8379