Invalid comparator: vector3df/vector2df operator<

[JosiahWI]

#define CATCH_CONFIG_MAIN
#include <catch.hpp>
#include <irrlicht.h>

#include <cmath>

TEST_CASE()
{
        irr::video::S3DVertex a;
        irr::video::S3DVertex b;
        a.Pos = irr::core::vector3df{0.0125, 0.0f, 0.0f};
        b.Pos = irr::core::vector3df{0.0126, 0.0f, 0.0f};
        CHECK(a != b);
        CHECK(a < b);
        CHECK(!(b < a));
}

This is the cause of minetest/minetest#14132.

[sfan5]

Where's the bug here?

[JosiahWI]

a != b, a < b, and b < a are all true at the same time. That doesn't make any sense, and it leads to incorrect sorting logic when used in STL containers.

[JosiahWI]

I take that back. This is the correct result of the test.