void main() {
    import std.algorithm: map, cartesianProduct;
    auto seq = [1, 2].map!(x => x);
    foreach (pair; cartesianProduct(seq, seq)) {}
}


dmd 2.067alpha gives:

...\dmd2\src\phobos\std\algorithm.d(14489,20): Error: function std.algorithm.cartesianProduct!(MapResult!(__lambda1, Result), MapResult!(__lambda1, Result)).cartesianProduct.Result.save cannot get frame pointer to main
...\dmd2\src\phobos\std\algorithm.d(14489,20): Error: function std.algorithm.cartesianProduct!(MapResult!(__lambda1, Result), MapResult!(__lambda1, Result)).cartesianProduct.Result.save cannot get frame pointer to main
...\dmd2\src\phobos\std\algorithm.d(14489,20): Error: function std.algorithm.cartesianProduct!(MapResult!(__lambda1, Result), MapResult!(__lambda1, Result)).cartesianProduct.Result.save cannot get frame pointer to main
...\dmd2\src\phobos\std\algorithm.d(14489,20): Error: function std.algorithm.cartesianProduct!(MapResult!(__lambda1, Result), MapResult!(__lambda1, Result)).cartesianProduct.Result.save cannot get frame pointer to main


Taking a look at the std.algorithm.cartesianProduct implementation:


auto cartesianProduct(RR...)(RR ranges)
    if (ranges.length >= 2 &&
        allSatisfy!(isForwardRange, RR) &&
        !anySatisfy!(isInfinite, RR))
{
...
    static struct Result
    {
...
        @property Result save()
        {
            Result copy; // Error message here *******
            foreach (i, r; ranges)
            {
                copy.ranges[i] = r.save;
                copy.current[i] = current[i].save;
            }
            copy.empty = this.empty;
            return copy;
        }
    }
...

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