Use after free, caused by iterator(slice) invalidation not prevented by dip1000/dip25

[PetarKirov]

Test case:

/+ dub.sdl:
dependency "automem" version="~>0.5.1"
dflags "-dip1000" "-dip25"
+/

void main() @safe
{
    import std.stdio : writefln;
    import std.experimental.allocator.mallocator: Mallocator;
    import automem.vector;

    auto vec1 = vector(1, 2, 3);
    int[] slice1 = vec1[];
    vec1.reserve(4096);
    int[] slice2 = vec1[];

    "slice1.ptr: %x, slice2.ptr: %x \nslice1: %s, slice2: %s"
        .writefln(&slice1[0], &slice2[0], slice1, slice2);
}

Sample output:

slice1.ptr: 7fc6d4d21000, slice2.ptr: 7fc6d3800000
slice1: [-724430832, 32710, -820732144], slice2: [1, 2, 3]

As far as I understand, languages with support for substructural type systems usually solve this by allowing either a single mutable reference or zero or more const references.

[atilaneves]

This isn't great, but it's convoluted. It shouldn't pass code review, but still, I'll have to think if there's a way to stop this from happening.